CA2048804A1 - Long life abrasive turbine blade tips - Google Patents
Long life abrasive turbine blade tipsInfo
- Publication number
- CA2048804A1 CA2048804A1 CA 2048804 CA2048804A CA2048804A1 CA 2048804 A1 CA2048804 A1 CA 2048804A1 CA 2048804 CA2048804 CA 2048804 CA 2048804 A CA2048804 A CA 2048804A CA 2048804 A1 CA2048804 A1 CA 2048804A1
- Authority
- CA
- Canada
- Prior art keywords
- abrasive particles
- metal
- layer
- particles
- abrasive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000002245 particle Substances 0.000 claims abstract description 208
- 229910052751 metal Inorganic materials 0.000 claims abstract description 145
- 239000002184 metal Substances 0.000 claims abstract description 145
- 239000010410 layer Substances 0.000 claims abstract description 128
- 239000000758 substrate Substances 0.000 claims abstract description 55
- 238000000034 method Methods 0.000 claims abstract description 53
- 239000000843 powder Substances 0.000 claims abstract description 53
- 238000004070 electrodeposition Methods 0.000 claims abstract description 18
- 239000011159 matrix material Substances 0.000 claims abstract 17
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 43
- 239000000463 material Substances 0.000 claims description 26
- 229910052759 nickel Inorganic materials 0.000 claims description 24
- 239000012790 adhesive layer Substances 0.000 claims description 17
- 238000000151 deposition Methods 0.000 claims description 16
- 238000000576 coating method Methods 0.000 claims description 14
- 239000011248 coating agent Substances 0.000 claims description 12
- 229910017052 cobalt Inorganic materials 0.000 claims description 12
- 239000010941 cobalt Substances 0.000 claims description 12
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 12
- 239000000853 adhesive Substances 0.000 claims description 9
- 230000001070 adhesive effect Effects 0.000 claims description 9
- 238000009713 electroplating Methods 0.000 claims description 9
- 238000009792 diffusion process Methods 0.000 claims description 5
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 230000004888 barrier function Effects 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 claims description 3
- 238000007254 oxidation reaction Methods 0.000 claims description 3
- 238000003980 solgel method Methods 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 claims description 2
- 230000007797 corrosion Effects 0.000 claims description 2
- 238000007772 electroless plating Methods 0.000 claims description 2
- 238000000265 homogenisation Methods 0.000 claims 3
- 239000004821 Contact adhesive Substances 0.000 claims 1
- 239000002356 single layer Substances 0.000 abstract description 10
- 238000005275 alloying Methods 0.000 abstract description 4
- 239000000203 mixture Substances 0.000 description 25
- 239000000956 alloy Substances 0.000 description 12
- 229910045601 alloy Inorganic materials 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 12
- 239000011651 chromium Substances 0.000 description 9
- 229910052782 aluminium Inorganic materials 0.000 description 8
- 239000000919 ceramic Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 230000002411 adverse Effects 0.000 description 6
- 239000003082 abrasive agent Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- 239000011261 inert gas Substances 0.000 description 5
- 238000007747 plating Methods 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 3
- 229910052735 hafnium Inorganic materials 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 238000007669 thermal treatment Methods 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000005253 cladding Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 235000015250 liver sausages Nutrition 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 229910052702 rhenium Inorganic materials 0.000 description 2
- XYSQXZCMOLNHOI-UHFFFAOYSA-N s-[2-[[4-(acetylsulfamoyl)phenyl]carbamoyl]phenyl] 5-pyridin-1-ium-1-ylpentanethioate;bromide Chemical compound [Br-].C1=CC(S(=O)(=O)NC(=O)C)=CC=C1NC(=O)C1=CC=CC=C1SC(=O)CCCC[N+]1=CC=CC=C1 XYSQXZCMOLNHOI-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- UOACKFBJUYNSLK-XRKIENNPSA-N Estradiol Cypionate Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H](C4=CC=C(O)C=C4CC3)CC[C@@]21C)C(=O)CCC1CCCC1 UOACKFBJUYNSLK-XRKIENNPSA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- -1 Sialon Inorganic materials 0.000 description 1
- 241000656145 Thyrsites atun Species 0.000 description 1
- 229910002065 alloy metal Inorganic materials 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- UFGZSIPAQKLCGR-UHFFFAOYSA-N chromium carbide Chemical compound [Cr]#C[Cr]C#[Cr] UFGZSIPAQKLCGR-UHFFFAOYSA-N 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- RLQJEEJISHYWON-UHFFFAOYSA-N flonicamid Chemical compound FC(F)(F)C1=CC=NC=C1C(=O)NCC#N RLQJEEJISHYWON-UHFFFAOYSA-N 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- UNASZPQZIFZUSI-UHFFFAOYSA-N methylidyneniobium Chemical compound [Nb]#C UNASZPQZIFZUSI-UHFFFAOYSA-N 0.000 description 1
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- NQLVQOSNDJXLKG-UHFFFAOYSA-N prosulfocarb Chemical compound CCCN(CCC)C(=O)SCC1=CC=CC=C1 NQLVQOSNDJXLKG-UHFFFAOYSA-N 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005486 sulfidation Methods 0.000 description 1
- 229910000601 superalloy Inorganic materials 0.000 description 1
- 229910003468 tantalcarbide Inorganic materials 0.000 description 1
- 238000005382 thermal cycling Methods 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 229910003470 tongbaite Inorganic materials 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
- F01D11/12—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D15/00—Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Polishing Bodies And Polishing Tools (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
PATENT
ABSTRACT
A method for applying a thin layer of uncoated abrasive particles to the surface of a metallic substrate. A single layer of particles and a thin layer of metal are first deposited on a matrix. A metal matrix comprising a fine alloying powder and a metal is then deposited over the first thin metal layer and the particles using co-electrodeposition The substrate and tip are thermally treated to homogenize the thin layer and the codeposited layer containing alloying powders and metal.
ABSTRACT
A method for applying a thin layer of uncoated abrasive particles to the surface of a metallic substrate. A single layer of particles and a thin layer of metal are first deposited on a matrix. A metal matrix comprising a fine alloying powder and a metal is then deposited over the first thin metal layer and the particles using co-electrodeposition The substrate and tip are thermally treated to homogenize the thin layer and the codeposited layer containing alloying powders and metal.
Description
2~8~
13DV-99~5 LONG kIF~ A~3RASIVE TURBINE BLAn~ TIPS
Background of the InventiQn The performance and efficiency of aircraft gas turbine engines are critically affected by the clearances that exist between the rotating and stationary components in the turbine. Thermal energy from the combustion of fuel in the combustor is converted into mechanical energy through an e~pansion process by impinging the hot gases of combustion onto a bladed rotor. As the clearances between the rotating bladed rotor and stationary, adjacent assemblies, such as the shroud, increase, the efficiency of the turbine decreases. It is thus desirable to maintain the clearances between the blades of the rotor and the shroud at a minimum without interfering with the rotation of the rotor.
2 0'~ PA~ENT
Among the factorY aff~cting the clearanca between the rotor blades and the shroud are erosion of the blaCe due to impingement of the hot combustion gases and removal of blade tip material du~ to shroud contact during engine operation.
Contact of the blade tip with the shroud or stator life is frequently referred to as rubbing, and occurs most frequently during early engine life. These rubs are attributed primarily to transient thermal and mechanical strains occurring during rapid changes in thrust level due to fast heat-ups, fast cooldowns also referred to as reburst cycles and in reheats.
Thermal espansion results because the rotor has less cooling than the shroud. During rapid increases in thrust levels, at which time additional combustion is occurring, the rotor thermally expands faster than the shroud. Thus, a component of the overall espansion is attributed to the thermal e~pansion of the rotor in e~cess of the stator or shroud.
~he rotation of the rotor also results in some expansion which also induces mechanical strain. This is another component of the overall e~pansion of the rotor.
When rotor e~pansion due to the combination of thermal expansion and mechanical strain e~ceeds the clearance between the rotor and the shroud during fast heat-ups and reburst cycles, rubbing occurs. If, in addition to the shroud wearing away the blade tip thereby shortening the blade, a portion of the shroud is also worn away, an additional undesirable clearance increase occurs which further reduces engine efficiency after the engine returns to normal operating conditions following the heat-up or reburst e~cursion.
Another cause of rub are maneuvering loads, which are mechanical forces resulting from loadings such as high 2 0 ~ o ~ ~ ~ 13DV-9935 G-turns, landings and sever~ turbulence. Unl~ke rub which is a result of thermal cycling and most frequ~ntly occurs in early engine operation, this rub occurs throughout engine life.
All successful turbine tips have the capability of abrading the cooperating turbine shroud as incursions occur during initial engine operation. E~amples of such blade tips are described in U.S. Pat. No. 4,744,725 to Eaton et al., U.S. Pat. No. 4,232,995 to Stalker et al.
and U.S. Pat. No. 3,199,836 to Moyer.
Because the abrasive material is not a structural material, and because its weight imposes stresses on the blade substrate as the blade rotates at high speeds, it is desirable to maintain the abrasive layer to the minimum possible thickness while retaining abrasive capability.
Thus, structures such as described in Stalker et al., U.S.
Pat. No. 4,232,995 and Eaton et al., U.S. Pat. No.
4,744,725, containing a single layer of abrasive particles embedded in a matris are preferred to multi-layered tips such as described in Moyer, U.S. Pat. ~o. 3,199,836.
New and improved methods of applying thin layers of abrasive material to the tips of turbine blades are re~uired. Several methods for application of thin layers of abrasive materials to turbine blades have been proposed.
An example of such a method is described in U.S.
Pat: No. 4,744,725 to Eaton et al. This method requires the cladding of ceramic particles with a metal, such as nickel, and then bonding them to the surface requiring the abrasive material with adhesive. The adhesive, which holds the particles in place, is then driven off at elevated temperatures as the nickel cladded particles are bonded or sintered to the substrate at elevated temperatures. Owing to the irregular shape of the particles and the thinness of the metallic cladding on the 2 ~ ~ g ~ 13 DV- 9 9 3 5 particles, the bond i8 relati~sly delicate. It ~ 8 ~lso necessary to carefully control the ~intsring or bonding temperatur~, as it is undesirabls to e~pose the substrate blade to temperatures which are too high, as changes to the microstructure and mechanical properties may occur.
After bonding, the particles are then oversprayed with a layer of matri~ material deposited by plasma arc spraying.
Another example of a method of applying thin layers of abrasive materials is described in U.S. Pat. No.
4,169,020 to Stal~er et al. This method requires the elevated temperature diffusion bonding of an o~idation-resistant, sulfidation-resistant and thermal fatigue-resistant alloy inner tip to the substrate material. Then, an outer tip portion comprising a metal matris entrapping a plurality of protruding abrasive particles is applied by electrodeposition.
U.S. Pat. No. 4,689,242 to Pike discloses another method of applying metal-coated ceramic particles to a metallic substrate. This method requires the deposition of a multiple layer coating on each particle, the layers comprising a first o~ide layer and a second metal layer capable of diffusing into the article surface. The substrate is coated with a binder solution consisting essentially of a low viscosity carrier liquid, a thermoplastic resin and metal particulates substantially small~r than the ceramic particles. A single layer of the ceramic particles are then disposed on the coated substrate. The article is then heated to diffuse a portion of the metal coating on each ceramic particle and t~ diffuse the particulates in a contact region into the metal coating and into the article surface, thus securely bondinq each particle to the surface. This process relies on capillary action to dra~ the metallic coated ceramic particles to the substrate surface as well as sintering to diffuse the metal from the coated particl~s and fro~ the coating into the substrate ~urface whils dr~vinq off the thermoplast~c binder. After ~intering, a matriY metal i~
applied over the sintered ceramic particles to fill in spaces between the particles. This matri~ is then simultaneously heated and presses to eliminate any voids which may be present and to securely bond the matri~ to the substrate by interdiffusion.
In still another method disclosed in U.S. Patent No.
4,854,196 to Mehan, a method of applying aluminum o~ide abrasive to the tip of a turbine blade by first coating the aluminum o~ide particles with platinum is disclosed.
The coated particles are then entrapped in the blade tip by introducinq the particles into a molten pool formed by melting a portion of the tip by laser melting. A problem with this method is the cost of platinum.
There is a need for simplified methods of applying thin layers of materials containing environmentally resistant abrasive particles in a metal matri~ to the surfaces of substrates which eliminates the necessity of precoating the abrasive articles prior to bringing them in contact with the substrate surface. It is also highly desirable to minimize or eliminate alto~ether elevated temperature treatments of heat-treatable substrates during the application of abrasive tips since such treatments, if not carefully controlled and monitored, may alter the microstructure of the substrate, hence affecting its mechanical properties and associated performance in service.
SUMMARY OF THE INVENTION
An advantage of the methods of the present invention is that thin coatings of materials containing abrasive 2 ~ ~ o 8 ~ ~ PATENT
13DV-gg3s par~icles may be applied to th~ surface of a metallic substrate without first precoating the abrasive particles. The espensive and time consuming step of coating abrasive particle~ prior to bringing them in contact with the surface of the æubstrate can thus be eliminated.
Another advantage of the present invention is that a thin, abrasive tip having a very high volume fraction of hard, ceramic particles for cutting the stator or shroud of a turbine may be applied to a turbine blade tip, thereby reducing the total thickness of the abrasive tip on the blade, and which may subsequently be lost to oxidation, thereby further decreasing rotor diameter.
A further advantage of the methods of the present invention is that thin coatings of materials containing a single layer, or multiple layers of abrasive particles, each layer forming a distinct plane parallel to other planes or layers and to the substrate surface may be applied, if desired.
Still a further advantage of the present invention is that a thin coating of materials containing abrasive particles may be applied to heat treatable substrates, such as nic~el base superalloy turbine blade tips, while minimizing the esposure of the substrate to thermal treatments.
In accordance with the present invention, an improved method for applying an abrasive layer to a metallic substrate is provided. The abrasive layer is comprised of abrasive particles having improved environmental resistance in a metal alloy matris material. The abrasive particles should be approsimately coplanar and should have about the same aspect ratio, although different aspect ratios can be used.
2 0L~88 ~ ~ 13~Y-9935 Th~ method for applying the abra3i~e lay~r to the metdllic substrate comprises first selecting abrasive particles having about the same size and shape. The abrasive particles are then brought into physical contact with the substrate surface, while ma~imizing the volume fraction of particles on the surface. While the subætrate to be coated and the abrasive particles are maintained in contact, a thin layer of a first metal is metallurgically deposited onto the surface of the substrate. This tbin layer of metal forms a bond with the metallic substrate surface, while simultaneously entrapping the abrasive particles in position against the substrate surface, thereby adhering the abrasive particles to the surface.
Because the thickness of this thin layer of the first metal is small in comparison to the size of the particles, the particles are not completely embedded in the thin layer by the deposition method. Finally, a second metal layer which may be comprised of the same metal as the first metal layer, or which may be comprised of a second metal distinct from the metal of the first layer, is applied over both the first thin metal layer and the particles. This second metal layer further has a distribution of fine alloying particles or powders which, following a heat treatment, forms on the metal substrate an abrasive layer havinq abrasive particles embedded in a substantially homogeneous or near homogeneous alloy metal matri~.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of e~ample, the principles of the invention.
~0~8~ PAT~NT
BRI2F DEfi~EIpTIoN OF T~ D~apI~Ç~
Fig. l is a cross-sectional view of a turbine blade having a tip formed of a single layer of substantially cubic-shaped abrasive particles embedded in a metal matri~.
Fig. 2 is a cross-sectional view of a piece of felt having an adhesive layer with abrasive particles applied, prior to removing e~cess particles.
Fig. 3 is a cross-sectional view of a piece of felt having an adhesive layer with abrasive particles applied, after removing excess particles.
Fig. 4 is a cross-sectional view of particle-bearing felt in physical contact with a turbine blade tip.
Fig. 5 is a cross-sectional view of particle-bearing felt in contact with a turbine blade tip after application of a a thin metal layer to the blade particle interface.
Fig. ~ is a cross-sectional view of a turbine blade tip having a thin metal layer bonded to the tip, with particles embedded in the layer and adhering to the tip as the adhesive-layered felt is peeled from the tip.
Fig. 7 is a cross-sectional view of a turbine blade tip after the adhesive-layered felt has been removed from the tip, but prior to deposition of the metal matri~.
Fig. 8 is a cross-sectional view of a turbine blade having an environmentally-resistant material which underiies the abrasive tip.
Fig. 9 is a cross-sectional view of a turbine blade having a tip formed of two layers of substantially cubic~shaped abrasive particles of substantially the same size embedded in a metal matri~.
~8$~
PATENT
13~V-9935 _g_ ~ETATLED DESCRIPTION OF THE INVENTION
An abrasive tip is applied to the tip of a turbine blade, such as those used in aircraft engine applications. The tip is u8ed to maintain a minimal clearance between the blade and the adjacent shroud or stator. During the early life of the engine, the tip rubs against the shroud, particularly during fast heat-ups and reburst cycles. Later in engine life, rub primarily occurs as a result of maneuvering loads. It is thus desirable for the abrasive tip to have a cutting ability while being held to the minimum practical thickness.
Also, because of the harsh environment, it is desirable for the blade tip to have good environmental resistance.
The metal removal mechanisms involved in the removal of adjacent shroud material by the turbine blade tip during engine operation are uni~ue because o~ the high temperatures, high surface speeds and low incursion rates associated with engine operation. Such conditions preclude the machining of chips which is the optimum stock removal route in conventional machining technology.
Analysis of the abrasive tip/metal shroud interactions at engine temperatures, tip speeds and machining rates indicate that the objective is to apply an abrasive and wear resistant material in a configuration which will, when rubbed against the shroud, cause the controlled transfer of shroud ~aterial to the blade tip system by abrasive wear. Blade tip speeds may be as high as about 1400 feet per second. Additionally, blade incursion on the shroud may be as high as 2 mils per incursion. There may be about a 4x10 9 to 8~10 9 inch incursion of the blade into the shroud per revolution of the bladed rotor during an incursion. At these tip speeds and incursion rates, no large metal chips are formed, 2 ~ 4 PATE~T
During initial engine operation, as the tip contacts the shroud, the metal i8 plowed aside by the abraQive particle~, although littl~ metal actually breaks ree from the shroud. The plowed metal i8 trapped between the blade tip and the shroud. This removal of shroud mater~al by the blade tip and subsequent entrapment of th~ removed metal between the tip and shroud (and continued removal of shroud material by plowing action) is known as abrasive wear. Large, angular abrasive particles in marked relief from the metal matris are desired during this stage.
After this initial rub, metal may be removed from the shroud by secondary adhesive wear, that is, wear due to welding of contacting asperities.
Referring now to Fig. l, a turbine blade lO having a dovetail end 12 and a tip end 14 is depicted. An abrasive tip 16 comprised of a metal matri~ material 18 and preferrably a single layer of abrasive particles 20 of approsimately the same size is attached to tip end 14 which forms the substrate.
The abrasive particles 20 are oxidation-resistant, corrosion-resistant and preferrably non-conducting. These particles are preferrably alumina, Sialon, Si3N4 or refractory metal carbides such as chromium carbide, tantalum carbide, niobium carbide or tungsten carbide.
The abrasive particles 20 should be generally cubic or cuboidal in shape, thereby having an aspect ratio of about l, although other shapes may be used. If other shapes are used, the particles should have the same aspect ratio. ~he cubic shaped particles are preferred because this configuration provides for optimum packing density of particles on the blade tip, thus maximizing their volume fraction. The size of the particles may vary from about 2 mils to about 15 mils on an edge, with the edge size being approximately the same (ie. about ~ l mil) in the PATENT
size selected, although particles ha~lng an qdge size of about 5-6 mils are most preferred.
Although cubic or cuboidal part~cles may be made by any effective process, it has been found that the Sol-Gel process produces a high concentration of cuboidal or cub~c particles of the desired size. Material8 produced by this proprietary process may be obtained from the 3-M Co. or the Norton Co.
After selecting particles of an appropriate size and shape, the particles are brought into physical contact with the metal substrate. Referring now to Fig. 2, a piece of felt 30 ha~ing an adhesive layer 32 on one surface 34 is brough~ into contact with selected abrasive particles 20. Abrasive particles 20 adhere to adhesive layer 32 on one surface 34 of felt 30. Abrasive particles 20 may form more than one layer over adhesive layer 32 as shown in Fig. 2. Because only a single layer of particles is preferred, e~cess particles may be removed from the felt by any known method, such as by shaking or blowing with an air stream sufficient to remove particles not contacting the adhesive without affecting those in contact with the adhesive, resulting in a single layer of abrasive particles 20 adhering to adhesive layer 32 as shown in Fig. 3. Referring now to Fig. 4, particles 20 are brought into physical contact with tip end 14 of blade 10.
While maintaining particles 20, adhering to adhesive layer 32 of felt layer 30, in physical contact with the substrate, depicted as tip 14 of blade 10 in Fig. 5, a thin layer of metal 36 is metallurgically deposited onto tip 14. Although any known method of maintaining contact between tip 14 and particles 20 may be used, it is preferred that a fi~ture (not shown) be used. The fi~ture holds the blade in contact with the particles adhering to felt layer 30 during deposition of layer 36. The force PATF2~T
13DV-gg3s applied to a3sure ~olid contact between the tip 14 3n~ the particles 20 may be supplied by gravity, by spring loading, clamping, or by any other ~uitable means.
Layer of metal 36, applied on the substrate, at tip 14 of Fig. 5, physically i8 located between tip 14, to which it i6 metallurgically attached, and adhesive layer 32 on felt layer 30. Thin metal layer 36 also at least partially entraps abrasive particles 20 thereby causing them to adhere to tip 14 after removal of the adhesive-containing layer, identified as felt in this e~ample.
Application of thin metal layer 36 may be accomplished by any deposition process which permits metal to contact the substrate tip 14 without affecting the physical contact between particles 20 and tip 14. One method of applying metal layer 36 is by electroless plating metal into the region between tip 14 and adhesive layer 32. However, the preferred method of application is complete immersion of blade tip 14 in an electroplating bath. Tip 14 of blade 10 is then electroplated, preferrably with a metal selected from the group consisting of nickel or cobalt. The thickness of metal layer 36 after electroplating is from about 0.1 to about 0.6 mils. Because the abrasive particles 20 are non-conducting in the preferred embodiment, no metal is deposited on them as a result of electroplating.
Referring now to Fi~. 6, after application of metal layer 36, felt layer 30 having adhesive layer 32 may be removed from contact with abrasive particles 20. Because particles 20 are mechanically trapped by metal layer 36, felt layer 30 may be peeled back. However, other methods of removal of particles 20 from adhesive layer 32 may be utilized, so long as the bond between particles 20 and metal layer 36 remains undisturbed. For e~ample, a 2 ~ ~ ~ 8 ~ ~ PATENT
13DV-~93s suitable solvent may be intro~uced between felt layer 30 and metal layer 36 to dissolve adhesive layer 32, thereby allowing removal of felt layar 30.
After ths removal of felt layer 30 and attached adhesive layer 32, abrasive particles 20 are in marked relief from thin metal layer 36 deposited over tip 14 as shown in Fi~. 7. Because the bond between particles 20 and layer 36 is insufficient for the desired application, it is necessary to apply a matri~ material over particles 20 before the abrasive tip can be effective in contact applications. Although the metal matris may be any metal or alloy, it is preferred that the metal matris be a metal or alloy which includes prealloyed powder or particles.
To accomplish the application of the metal matris material, fine particles of prealloyed powder are mised in an electroplating solution of a metal or alloy. The fine prealloyed powder particles and solution readily flow into the space between the abrasive particles. The prealloyed powder particles are selected and applied in the appropriate volume fraction with the plating solution so that the metal matris, after a suitable thermal treatment has the desired chemical composition. For esample, a suitable volume fraction of NiCrAlY or CoNiCrAlY powder particles, up to about 60%, are mised in a solution o cobalt and are subseguently entrapped in a matris of cobalt. Alternatively, CoCrAlY particles are mised in a solution of nickel and are subsequently entrapped in a matris of nickel. The turbine blade tip is heat treated so that the metal matris having the entrapped powder particles is homogenized by a diffusion heat treatment, thereby yielding a homogeneous matris having the desired chemical composition.
2 ~ PAT~NS
Th~ ~econd metJl ~r alloy hav~ng fine pre~lloyed powder particles i8 depos~ted over thin metal layer 36 and abrasive part~cles 20 to form a metal containing fine prealloyed powder particles surrounding abrasivo particles S 20, preferably using co-electrodeposition.
Co-electrodeposition, dev~loped by Bristol Aerojet Limited, is described in U.S. Patent No. 4,305,792 incorporated herein by reference. In this process, the article to be coated is placed in a barrel together witb the particles, and the barrel is placed in a plating bath and rotated therein. The barrel has an opening covered by a cover which is pervious to the plating solution, but impervious to the particles. The article is thus flowed over by solution within the barrel which can have a high lS concentration of particles, but there are no particles in the part of the bath outside the barrel. The process may be electroless or electrolytic. The depositing of the matri~ of this invention may be accomplished by any suitable co-electrodeposition techni~ue.
This second metal is applied over the abrasive particles in relief and the first thin metal layer 36. It is applied as a fine powder-containing plating solution in which the solutioh preferably is selected from the group of Co, and Ni, and is usually the same metal as the first thin layer The prealloyed, fine powder in the plating solution is a MCrAlY powder wherein M is an element selected from the group of Co, Ni and combinations thereof.
After deposition of the second metal containing the prealloyed fine powders, the second metal and particles may completely envelop particles 20 or may leave abrasive particles 20 in slight relief as shown in Fig. 1. The preferred thickness of second metal matri~ 18 is approximately 60 to 70~ of the average size of abrasive particles 20. For example, when the preferred particle 2 ~ PA~ENT
siz~ of about 5 to 6 mils is selecte~, th~ ~r~farred secon~ metal deposit thicknes~ is from about 3 to about 4.5 mils. Tha preferr~d m~thod of depo~iting second containing fine prealloy~d powder part~cles (not shown) over abrasive particles 20 and thin layer 36 to form abrasive tip 16 is by co-electrodeposition.
A single layer of abrasive particles ~0 is enveloped in a first thin metal layer 36 on top of which is deposited a second metal matri~ 18 having prealloyed fine powder or particles ~not shown). In order to form an abrasive tip 16 having abrasive particles embedded in a uniform metal matris material 18 on tip end 14 of turbine blade lO~ it is necessary to homogenize both the first thin metal layer 36, and the fine alloying powder-containinq second metal layer. The homogenizing is accomplished by a homogenizing thermal treatment which must be for a sufficient time and at a sufficient temperature to achieve a substantially uniform alloy composition throughout the metal matri~ 18 and thin metal layer 36 applied onto tip end 14, without adversely affecting the substrate material.
In the following esamples, the volume fraction of pre-alloyed powder is typically about 60~ the co-electrodeposited materials, the metal solution com~rising the balance. This volume fraction will vary depending upon the final desired composition of the metal matris, the metal solution composition and the alloy powder composition.
In a preferred embodiment, second metal matris 18 may be Ni or Co, containinq a MCrAlY powder, both the metal and powder selected so as to be compatible with thin metal layer 36. Thus, when thin metal layer 36 is selected from the group consisting of Ni and Co, the metal of the second metal matris is also selected from the group 2 ~ ~ ~ 8 ~ ~ PAT~NT
l~DV-9935 Ni and Co, and MCrAlY ~lloy powder ~ chosen auch th~t M
i~ selected from the group of elements con~isting of Co and Ni. Most preferably, first metal layer 36 and the second metal are the same element, either both Ni or both Co, and M of the MCrAlY ls the remaining element (i.e., when second metal is Co, the powder is ~iCrAlY) or a combination of Ni and Co i.e., NiCoCrAlY.
EXAMPL~ 1 After application of a first cobalt thin layer 36 by electrodeposition and fine CoNiCrAlY powders in a second cobalt layer over the first thin layer by co-electrodeposition, thereby surrounding abrasive particles 20 on the tip of a Rene' 80 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 4 -8 hours at about 1925-1950F. Th~ metal - composition is initially essentially 100~ Co and incidental elements which do not adversely affect the `
composition while the composition of the prealloyed CoNiCrAlY powder is, by weight, about about 54% Ni, about 32~ Cr, about 13.5% Al, about 0.8 Y, and incidental elements which do not adversely affect the alloy powder.
The heat treatment substantially homogenizes the metal matri~ 18 surrounding abrasive particles 20, so that the composition of metal matri~ 18 after heat treatment is, by weight, ahout 31-33% Ni, about 19-22% Cr, about 7-9% Al, about 0.35-0.65~ Y, and the balance Co and small amounts of incidental elements which do not adversely affect the alloy.
$ ~ ~
PATE~T
13DV-993s After appl~cation of a first cobalt thin layer 36 by electrodeposition and fine CoNiCr~lY powders in a second cobalt layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on th~
tip of a Rene' N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 1975-2050F. The metal composition is initially essentially 100~ Co and incidental elements which do not adveræely affect the alloy, while the composition of the fine prealloyed powder is, by weight, about about 54% Ni, about 32% Cr, about 13.5~ Al, about 0.8 Y, and incidental elements which do not adversely affect the alloy powder.
The heat treatment substantially homogenizes metal matris 18 surrounding the abrasive particles, so that the composition of metal matris 18 after heat treatment is, by weight, about 31-33% Ni, about 19-22~ Cr, about 7-9% Al, about 0.35-0.65% Y, and the balance Co and small amounts of incidental elements which do not adversely affect the alloy.
After application of a first cobalt thin layer 36 by eleçtrodeposition, and fine powders having a composition by weight of about 20% Co, 10.2% Al, 10.7~ Ta, 11.3 % Cr, 2.5% Hf, 4.7% Re, 0.2% C, 8.3% W and the balance Ni and incidental impurities in a second nickel layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on the tip of a Rene~ N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 2000-2075F. This heat treatment substantially homogenizes metal matris 18, thin layer 36 and the fine powder so that the composition of the metal matris after heat treatment is the composition of Rene' 142, Table 1.
2 ~ 8 0 4 PATENT
13DV-9g3s ~Xa~PLE 4 After application of a first cobalt thin layer 36 by electrodeposition, and fine powders having a composit~on by weight of about 6.7~ Co, 10% Al, 8.3% Ta, 15~ Cr, 1.5%
Hf, 2.5~ Mo, 2.3~ Re, 0.03~ Zr and the balance ~i and incidental impurities in a second nickel layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on the tip of a Rene' N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 2000-2075F. The heat treatment substantially homogenizes metal matris 18, thin layer 36 and the fine powder so that the composition of the metal matri2 after heat treatment is the composition of PS6MY, see Table 1.
After application of a first cobalt thin layer by electrodeposition and fine powders Xaving a composition by weight of about 16.7% Co, 10.8~ Al, 10% Ta, 30~ Cr, 0.83%
Hf, 3.3% Re, 0.07% C, 0.02% Zr and the balance Ni and incidental impurities in a second nickel layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on the tip of a Rene' N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 2000-2075F. This heat treatment substantially homogenizes metal matris 18, thin layer 36 and the fine powders so that the composition of the metal matris after heat treatment is the composition of ~C-53, see Table 1.
2 0 ~ L~ PATENT
Table 1 Nominal Composition PS6MX Rene' 142 BC-53 Ni Bal. Bal. Bal.
Co 4 12 10 Al 6 6.1 6.5 Ta 5 6.4 6 Cr 9 6.76 18 Hf 0.9 1.49 O.S
Mo 1.5 --- 0 Re 1.4 2.84 2.0 C 0 .11 0.05 Zr 0.02 --- 0.01 lS W ___ 5 While the process of the present invention eliminates the necessity for providing coated abrasive particles, if desired particles 20 may optionally be coated with a coating, such as a diffusion barrier coating, prior to placing the particles in contact with adhesive layer 32.
However, it is preferred to use nonconductive and nonsilicon-bearing particles, such as alumina (~12O3).
' : :
-20i~8~
PATENT
13~V-9935 Because the smbodiment of the in~ention shown in Fig. 1 is thin, be~ng comprised of a single layer of abrasive particles 20 emb2dded in a metal matri~
18, it is espected that abrasive tip 16 will be removed from tip 14 of blade lO in a relatively short time as compared to overall blade life. In such a case, it may be desirable to optionally coat tip 14 with an environmentally resistant material prior to application of the abrasive tip. In such a case, the abrasive tip is applied by the process of the present invention over the environmentally resistant material, in which case the environmentally resistant material is substituted for the substrate in the above description of the invention. A commonly used environmentally resistant material has a nominal composition of, by weight, of about 33% Ni, about 23%
Cr, about 4% Al, about 0.5~ C, about 3% W, about 33%
Co, about 3% ~a, about 0.75% Si. along with incidental impurities. This composition is described in U.S. Pat. No. 4,227,703 issued Oct. 14, 1980, which is hereby incorporated by reference. ~owever, this environmentally resistant undercoat is provided by way of esample, and is not meant to limit application of the long life abrasive tip of the present invention solely over this environmentally resistant undercoat. A turbine blade having an environmentally resistant layer 44 overlaying tip 14 is shown in Fig. 8.
If early removal of the thin abrasive tip is undesirable during engine operation, the method of the present invention can be used to apply multiple layers of particles, so that even if the initial layer of particles is worn off the tip, additional layers of particles remain so that additional 2 0 ~1 ~ 8) ~ L~ ~3DY-9935 material can be abraded from the shroud, if necessary, Referring now to Fig. 9, n turbine blade 80 having an abrasive tip 82 with two rows of abrasive particles, 8~ and 86 embedded in a m~tal matri~ 88 i~ depicted. Abrasive particles 84 ~n the layer ~losest to blade tip 90 ar~ coplanar an~
parallel to the plane of abrasive particles 86 forming the layer furthest from blade tip 90.
Although particles 84 and 86 are shown as being about the same size, it may be desirable to size the particles such that particles 86 are larger, which is desirable during three-body-abrasive wear which occurs early in engine operation, while particles 84, which are smaller, will remain after the layer containing particles 86 has worn away. The smaller particles in the layer closer to the tip will be more effective during the adhesive wear phases which may occur during later stages of engine operation.
In light of the foregoing discussion, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments, methods and compositions herein described. Numerous modifications, changes, substitutions and equivalents will now become apparent to those skilled in the art, all of which fall within the scope contemplated by the invention.
13DV-99~5 LONG kIF~ A~3RASIVE TURBINE BLAn~ TIPS
Background of the InventiQn The performance and efficiency of aircraft gas turbine engines are critically affected by the clearances that exist between the rotating and stationary components in the turbine. Thermal energy from the combustion of fuel in the combustor is converted into mechanical energy through an e~pansion process by impinging the hot gases of combustion onto a bladed rotor. As the clearances between the rotating bladed rotor and stationary, adjacent assemblies, such as the shroud, increase, the efficiency of the turbine decreases. It is thus desirable to maintain the clearances between the blades of the rotor and the shroud at a minimum without interfering with the rotation of the rotor.
2 0'~ PA~ENT
Among the factorY aff~cting the clearanca between the rotor blades and the shroud are erosion of the blaCe due to impingement of the hot combustion gases and removal of blade tip material du~ to shroud contact during engine operation.
Contact of the blade tip with the shroud or stator life is frequently referred to as rubbing, and occurs most frequently during early engine life. These rubs are attributed primarily to transient thermal and mechanical strains occurring during rapid changes in thrust level due to fast heat-ups, fast cooldowns also referred to as reburst cycles and in reheats.
Thermal espansion results because the rotor has less cooling than the shroud. During rapid increases in thrust levels, at which time additional combustion is occurring, the rotor thermally expands faster than the shroud. Thus, a component of the overall espansion is attributed to the thermal e~pansion of the rotor in e~cess of the stator or shroud.
~he rotation of the rotor also results in some expansion which also induces mechanical strain. This is another component of the overall e~pansion of the rotor.
When rotor e~pansion due to the combination of thermal expansion and mechanical strain e~ceeds the clearance between the rotor and the shroud during fast heat-ups and reburst cycles, rubbing occurs. If, in addition to the shroud wearing away the blade tip thereby shortening the blade, a portion of the shroud is also worn away, an additional undesirable clearance increase occurs which further reduces engine efficiency after the engine returns to normal operating conditions following the heat-up or reburst e~cursion.
Another cause of rub are maneuvering loads, which are mechanical forces resulting from loadings such as high 2 0 ~ o ~ ~ ~ 13DV-9935 G-turns, landings and sever~ turbulence. Unl~ke rub which is a result of thermal cycling and most frequ~ntly occurs in early engine operation, this rub occurs throughout engine life.
All successful turbine tips have the capability of abrading the cooperating turbine shroud as incursions occur during initial engine operation. E~amples of such blade tips are described in U.S. Pat. No. 4,744,725 to Eaton et al., U.S. Pat. No. 4,232,995 to Stalker et al.
and U.S. Pat. No. 3,199,836 to Moyer.
Because the abrasive material is not a structural material, and because its weight imposes stresses on the blade substrate as the blade rotates at high speeds, it is desirable to maintain the abrasive layer to the minimum possible thickness while retaining abrasive capability.
Thus, structures such as described in Stalker et al., U.S.
Pat. No. 4,232,995 and Eaton et al., U.S. Pat. No.
4,744,725, containing a single layer of abrasive particles embedded in a matris are preferred to multi-layered tips such as described in Moyer, U.S. Pat. ~o. 3,199,836.
New and improved methods of applying thin layers of abrasive material to the tips of turbine blades are re~uired. Several methods for application of thin layers of abrasive materials to turbine blades have been proposed.
An example of such a method is described in U.S.
Pat: No. 4,744,725 to Eaton et al. This method requires the cladding of ceramic particles with a metal, such as nickel, and then bonding them to the surface requiring the abrasive material with adhesive. The adhesive, which holds the particles in place, is then driven off at elevated temperatures as the nickel cladded particles are bonded or sintered to the substrate at elevated temperatures. Owing to the irregular shape of the particles and the thinness of the metallic cladding on the 2 ~ ~ g ~ 13 DV- 9 9 3 5 particles, the bond i8 relati~sly delicate. It ~ 8 ~lso necessary to carefully control the ~intsring or bonding temperatur~, as it is undesirabls to e~pose the substrate blade to temperatures which are too high, as changes to the microstructure and mechanical properties may occur.
After bonding, the particles are then oversprayed with a layer of matri~ material deposited by plasma arc spraying.
Another example of a method of applying thin layers of abrasive materials is described in U.S. Pat. No.
4,169,020 to Stal~er et al. This method requires the elevated temperature diffusion bonding of an o~idation-resistant, sulfidation-resistant and thermal fatigue-resistant alloy inner tip to the substrate material. Then, an outer tip portion comprising a metal matris entrapping a plurality of protruding abrasive particles is applied by electrodeposition.
U.S. Pat. No. 4,689,242 to Pike discloses another method of applying metal-coated ceramic particles to a metallic substrate. This method requires the deposition of a multiple layer coating on each particle, the layers comprising a first o~ide layer and a second metal layer capable of diffusing into the article surface. The substrate is coated with a binder solution consisting essentially of a low viscosity carrier liquid, a thermoplastic resin and metal particulates substantially small~r than the ceramic particles. A single layer of the ceramic particles are then disposed on the coated substrate. The article is then heated to diffuse a portion of the metal coating on each ceramic particle and t~ diffuse the particulates in a contact region into the metal coating and into the article surface, thus securely bondinq each particle to the surface. This process relies on capillary action to dra~ the metallic coated ceramic particles to the substrate surface as well as sintering to diffuse the metal from the coated particl~s and fro~ the coating into the substrate ~urface whils dr~vinq off the thermoplast~c binder. After ~intering, a matriY metal i~
applied over the sintered ceramic particles to fill in spaces between the particles. This matri~ is then simultaneously heated and presses to eliminate any voids which may be present and to securely bond the matri~ to the substrate by interdiffusion.
In still another method disclosed in U.S. Patent No.
4,854,196 to Mehan, a method of applying aluminum o~ide abrasive to the tip of a turbine blade by first coating the aluminum o~ide particles with platinum is disclosed.
The coated particles are then entrapped in the blade tip by introducinq the particles into a molten pool formed by melting a portion of the tip by laser melting. A problem with this method is the cost of platinum.
There is a need for simplified methods of applying thin layers of materials containing environmentally resistant abrasive particles in a metal matri~ to the surfaces of substrates which eliminates the necessity of precoating the abrasive articles prior to bringing them in contact with the substrate surface. It is also highly desirable to minimize or eliminate alto~ether elevated temperature treatments of heat-treatable substrates during the application of abrasive tips since such treatments, if not carefully controlled and monitored, may alter the microstructure of the substrate, hence affecting its mechanical properties and associated performance in service.
SUMMARY OF THE INVENTION
An advantage of the methods of the present invention is that thin coatings of materials containing abrasive 2 ~ ~ o 8 ~ ~ PATENT
13DV-gg3s par~icles may be applied to th~ surface of a metallic substrate without first precoating the abrasive particles. The espensive and time consuming step of coating abrasive particle~ prior to bringing them in contact with the surface of the æubstrate can thus be eliminated.
Another advantage of the present invention is that a thin, abrasive tip having a very high volume fraction of hard, ceramic particles for cutting the stator or shroud of a turbine may be applied to a turbine blade tip, thereby reducing the total thickness of the abrasive tip on the blade, and which may subsequently be lost to oxidation, thereby further decreasing rotor diameter.
A further advantage of the methods of the present invention is that thin coatings of materials containing a single layer, or multiple layers of abrasive particles, each layer forming a distinct plane parallel to other planes or layers and to the substrate surface may be applied, if desired.
Still a further advantage of the present invention is that a thin coating of materials containing abrasive particles may be applied to heat treatable substrates, such as nic~el base superalloy turbine blade tips, while minimizing the esposure of the substrate to thermal treatments.
In accordance with the present invention, an improved method for applying an abrasive layer to a metallic substrate is provided. The abrasive layer is comprised of abrasive particles having improved environmental resistance in a metal alloy matris material. The abrasive particles should be approsimately coplanar and should have about the same aspect ratio, although different aspect ratios can be used.
2 0L~88 ~ ~ 13~Y-9935 Th~ method for applying the abra3i~e lay~r to the metdllic substrate comprises first selecting abrasive particles having about the same size and shape. The abrasive particles are then brought into physical contact with the substrate surface, while ma~imizing the volume fraction of particles on the surface. While the subætrate to be coated and the abrasive particles are maintained in contact, a thin layer of a first metal is metallurgically deposited onto the surface of the substrate. This tbin layer of metal forms a bond with the metallic substrate surface, while simultaneously entrapping the abrasive particles in position against the substrate surface, thereby adhering the abrasive particles to the surface.
Because the thickness of this thin layer of the first metal is small in comparison to the size of the particles, the particles are not completely embedded in the thin layer by the deposition method. Finally, a second metal layer which may be comprised of the same metal as the first metal layer, or which may be comprised of a second metal distinct from the metal of the first layer, is applied over both the first thin metal layer and the particles. This second metal layer further has a distribution of fine alloying particles or powders which, following a heat treatment, forms on the metal substrate an abrasive layer havinq abrasive particles embedded in a substantially homogeneous or near homogeneous alloy metal matri~.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of e~ample, the principles of the invention.
~0~8~ PAT~NT
BRI2F DEfi~EIpTIoN OF T~ D~apI~Ç~
Fig. l is a cross-sectional view of a turbine blade having a tip formed of a single layer of substantially cubic-shaped abrasive particles embedded in a metal matri~.
Fig. 2 is a cross-sectional view of a piece of felt having an adhesive layer with abrasive particles applied, prior to removing e~cess particles.
Fig. 3 is a cross-sectional view of a piece of felt having an adhesive layer with abrasive particles applied, after removing excess particles.
Fig. 4 is a cross-sectional view of particle-bearing felt in physical contact with a turbine blade tip.
Fig. 5 is a cross-sectional view of particle-bearing felt in contact with a turbine blade tip after application of a a thin metal layer to the blade particle interface.
Fig. ~ is a cross-sectional view of a turbine blade tip having a thin metal layer bonded to the tip, with particles embedded in the layer and adhering to the tip as the adhesive-layered felt is peeled from the tip.
Fig. 7 is a cross-sectional view of a turbine blade tip after the adhesive-layered felt has been removed from the tip, but prior to deposition of the metal matri~.
Fig. 8 is a cross-sectional view of a turbine blade having an environmentally-resistant material which underiies the abrasive tip.
Fig. 9 is a cross-sectional view of a turbine blade having a tip formed of two layers of substantially cubic~shaped abrasive particles of substantially the same size embedded in a metal matri~.
~8$~
PATENT
13~V-9935 _g_ ~ETATLED DESCRIPTION OF THE INVENTION
An abrasive tip is applied to the tip of a turbine blade, such as those used in aircraft engine applications. The tip is u8ed to maintain a minimal clearance between the blade and the adjacent shroud or stator. During the early life of the engine, the tip rubs against the shroud, particularly during fast heat-ups and reburst cycles. Later in engine life, rub primarily occurs as a result of maneuvering loads. It is thus desirable for the abrasive tip to have a cutting ability while being held to the minimum practical thickness.
Also, because of the harsh environment, it is desirable for the blade tip to have good environmental resistance.
The metal removal mechanisms involved in the removal of adjacent shroud material by the turbine blade tip during engine operation are uni~ue because o~ the high temperatures, high surface speeds and low incursion rates associated with engine operation. Such conditions preclude the machining of chips which is the optimum stock removal route in conventional machining technology.
Analysis of the abrasive tip/metal shroud interactions at engine temperatures, tip speeds and machining rates indicate that the objective is to apply an abrasive and wear resistant material in a configuration which will, when rubbed against the shroud, cause the controlled transfer of shroud ~aterial to the blade tip system by abrasive wear. Blade tip speeds may be as high as about 1400 feet per second. Additionally, blade incursion on the shroud may be as high as 2 mils per incursion. There may be about a 4x10 9 to 8~10 9 inch incursion of the blade into the shroud per revolution of the bladed rotor during an incursion. At these tip speeds and incursion rates, no large metal chips are formed, 2 ~ 4 PATE~T
During initial engine operation, as the tip contacts the shroud, the metal i8 plowed aside by the abraQive particle~, although littl~ metal actually breaks ree from the shroud. The plowed metal i8 trapped between the blade tip and the shroud. This removal of shroud mater~al by the blade tip and subsequent entrapment of th~ removed metal between the tip and shroud (and continued removal of shroud material by plowing action) is known as abrasive wear. Large, angular abrasive particles in marked relief from the metal matris are desired during this stage.
After this initial rub, metal may be removed from the shroud by secondary adhesive wear, that is, wear due to welding of contacting asperities.
Referring now to Fig. l, a turbine blade lO having a dovetail end 12 and a tip end 14 is depicted. An abrasive tip 16 comprised of a metal matri~ material 18 and preferrably a single layer of abrasive particles 20 of approsimately the same size is attached to tip end 14 which forms the substrate.
The abrasive particles 20 are oxidation-resistant, corrosion-resistant and preferrably non-conducting. These particles are preferrably alumina, Sialon, Si3N4 or refractory metal carbides such as chromium carbide, tantalum carbide, niobium carbide or tungsten carbide.
The abrasive particles 20 should be generally cubic or cuboidal in shape, thereby having an aspect ratio of about l, although other shapes may be used. If other shapes are used, the particles should have the same aspect ratio. ~he cubic shaped particles are preferred because this configuration provides for optimum packing density of particles on the blade tip, thus maximizing their volume fraction. The size of the particles may vary from about 2 mils to about 15 mils on an edge, with the edge size being approximately the same (ie. about ~ l mil) in the PATENT
size selected, although particles ha~lng an qdge size of about 5-6 mils are most preferred.
Although cubic or cuboidal part~cles may be made by any effective process, it has been found that the Sol-Gel process produces a high concentration of cuboidal or cub~c particles of the desired size. Material8 produced by this proprietary process may be obtained from the 3-M Co. or the Norton Co.
After selecting particles of an appropriate size and shape, the particles are brought into physical contact with the metal substrate. Referring now to Fig. 2, a piece of felt 30 ha~ing an adhesive layer 32 on one surface 34 is brough~ into contact with selected abrasive particles 20. Abrasive particles 20 adhere to adhesive layer 32 on one surface 34 of felt 30. Abrasive particles 20 may form more than one layer over adhesive layer 32 as shown in Fig. 2. Because only a single layer of particles is preferred, e~cess particles may be removed from the felt by any known method, such as by shaking or blowing with an air stream sufficient to remove particles not contacting the adhesive without affecting those in contact with the adhesive, resulting in a single layer of abrasive particles 20 adhering to adhesive layer 32 as shown in Fig. 3. Referring now to Fig. 4, particles 20 are brought into physical contact with tip end 14 of blade 10.
While maintaining particles 20, adhering to adhesive layer 32 of felt layer 30, in physical contact with the substrate, depicted as tip 14 of blade 10 in Fig. 5, a thin layer of metal 36 is metallurgically deposited onto tip 14. Although any known method of maintaining contact between tip 14 and particles 20 may be used, it is preferred that a fi~ture (not shown) be used. The fi~ture holds the blade in contact with the particles adhering to felt layer 30 during deposition of layer 36. The force PATF2~T
13DV-gg3s applied to a3sure ~olid contact between the tip 14 3n~ the particles 20 may be supplied by gravity, by spring loading, clamping, or by any other ~uitable means.
Layer of metal 36, applied on the substrate, at tip 14 of Fig. 5, physically i8 located between tip 14, to which it i6 metallurgically attached, and adhesive layer 32 on felt layer 30. Thin metal layer 36 also at least partially entraps abrasive particles 20 thereby causing them to adhere to tip 14 after removal of the adhesive-containing layer, identified as felt in this e~ample.
Application of thin metal layer 36 may be accomplished by any deposition process which permits metal to contact the substrate tip 14 without affecting the physical contact between particles 20 and tip 14. One method of applying metal layer 36 is by electroless plating metal into the region between tip 14 and adhesive layer 32. However, the preferred method of application is complete immersion of blade tip 14 in an electroplating bath. Tip 14 of blade 10 is then electroplated, preferrably with a metal selected from the group consisting of nickel or cobalt. The thickness of metal layer 36 after electroplating is from about 0.1 to about 0.6 mils. Because the abrasive particles 20 are non-conducting in the preferred embodiment, no metal is deposited on them as a result of electroplating.
Referring now to Fi~. 6, after application of metal layer 36, felt layer 30 having adhesive layer 32 may be removed from contact with abrasive particles 20. Because particles 20 are mechanically trapped by metal layer 36, felt layer 30 may be peeled back. However, other methods of removal of particles 20 from adhesive layer 32 may be utilized, so long as the bond between particles 20 and metal layer 36 remains undisturbed. For e~ample, a 2 ~ ~ ~ 8 ~ ~ PATENT
13DV-~93s suitable solvent may be intro~uced between felt layer 30 and metal layer 36 to dissolve adhesive layer 32, thereby allowing removal of felt layar 30.
After ths removal of felt layer 30 and attached adhesive layer 32, abrasive particles 20 are in marked relief from thin metal layer 36 deposited over tip 14 as shown in Fi~. 7. Because the bond between particles 20 and layer 36 is insufficient for the desired application, it is necessary to apply a matri~ material over particles 20 before the abrasive tip can be effective in contact applications. Although the metal matris may be any metal or alloy, it is preferred that the metal matris be a metal or alloy which includes prealloyed powder or particles.
To accomplish the application of the metal matris material, fine particles of prealloyed powder are mised in an electroplating solution of a metal or alloy. The fine prealloyed powder particles and solution readily flow into the space between the abrasive particles. The prealloyed powder particles are selected and applied in the appropriate volume fraction with the plating solution so that the metal matris, after a suitable thermal treatment has the desired chemical composition. For esample, a suitable volume fraction of NiCrAlY or CoNiCrAlY powder particles, up to about 60%, are mised in a solution o cobalt and are subseguently entrapped in a matris of cobalt. Alternatively, CoCrAlY particles are mised in a solution of nickel and are subsequently entrapped in a matris of nickel. The turbine blade tip is heat treated so that the metal matris having the entrapped powder particles is homogenized by a diffusion heat treatment, thereby yielding a homogeneous matris having the desired chemical composition.
2 ~ PAT~NS
Th~ ~econd metJl ~r alloy hav~ng fine pre~lloyed powder particles i8 depos~ted over thin metal layer 36 and abrasive part~cles 20 to form a metal containing fine prealloyed powder particles surrounding abrasivo particles S 20, preferably using co-electrodeposition.
Co-electrodeposition, dev~loped by Bristol Aerojet Limited, is described in U.S. Patent No. 4,305,792 incorporated herein by reference. In this process, the article to be coated is placed in a barrel together witb the particles, and the barrel is placed in a plating bath and rotated therein. The barrel has an opening covered by a cover which is pervious to the plating solution, but impervious to the particles. The article is thus flowed over by solution within the barrel which can have a high lS concentration of particles, but there are no particles in the part of the bath outside the barrel. The process may be electroless or electrolytic. The depositing of the matri~ of this invention may be accomplished by any suitable co-electrodeposition techni~ue.
This second metal is applied over the abrasive particles in relief and the first thin metal layer 36. It is applied as a fine powder-containing plating solution in which the solutioh preferably is selected from the group of Co, and Ni, and is usually the same metal as the first thin layer The prealloyed, fine powder in the plating solution is a MCrAlY powder wherein M is an element selected from the group of Co, Ni and combinations thereof.
After deposition of the second metal containing the prealloyed fine powders, the second metal and particles may completely envelop particles 20 or may leave abrasive particles 20 in slight relief as shown in Fig. 1. The preferred thickness of second metal matri~ 18 is approximately 60 to 70~ of the average size of abrasive particles 20. For example, when the preferred particle 2 ~ PA~ENT
siz~ of about 5 to 6 mils is selecte~, th~ ~r~farred secon~ metal deposit thicknes~ is from about 3 to about 4.5 mils. Tha preferr~d m~thod of depo~iting second containing fine prealloy~d powder part~cles (not shown) over abrasive particles 20 and thin layer 36 to form abrasive tip 16 is by co-electrodeposition.
A single layer of abrasive particles ~0 is enveloped in a first thin metal layer 36 on top of which is deposited a second metal matri~ 18 having prealloyed fine powder or particles ~not shown). In order to form an abrasive tip 16 having abrasive particles embedded in a uniform metal matris material 18 on tip end 14 of turbine blade lO~ it is necessary to homogenize both the first thin metal layer 36, and the fine alloying powder-containinq second metal layer. The homogenizing is accomplished by a homogenizing thermal treatment which must be for a sufficient time and at a sufficient temperature to achieve a substantially uniform alloy composition throughout the metal matri~ 18 and thin metal layer 36 applied onto tip end 14, without adversely affecting the substrate material.
In the following esamples, the volume fraction of pre-alloyed powder is typically about 60~ the co-electrodeposited materials, the metal solution com~rising the balance. This volume fraction will vary depending upon the final desired composition of the metal matris, the metal solution composition and the alloy powder composition.
In a preferred embodiment, second metal matris 18 may be Ni or Co, containinq a MCrAlY powder, both the metal and powder selected so as to be compatible with thin metal layer 36. Thus, when thin metal layer 36 is selected from the group consisting of Ni and Co, the metal of the second metal matris is also selected from the group 2 ~ ~ ~ 8 ~ ~ PAT~NT
l~DV-9935 Ni and Co, and MCrAlY ~lloy powder ~ chosen auch th~t M
i~ selected from the group of elements con~isting of Co and Ni. Most preferably, first metal layer 36 and the second metal are the same element, either both Ni or both Co, and M of the MCrAlY ls the remaining element (i.e., when second metal is Co, the powder is ~iCrAlY) or a combination of Ni and Co i.e., NiCoCrAlY.
EXAMPL~ 1 After application of a first cobalt thin layer 36 by electrodeposition and fine CoNiCrAlY powders in a second cobalt layer over the first thin layer by co-electrodeposition, thereby surrounding abrasive particles 20 on the tip of a Rene' 80 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 4 -8 hours at about 1925-1950F. Th~ metal - composition is initially essentially 100~ Co and incidental elements which do not adversely affect the `
composition while the composition of the prealloyed CoNiCrAlY powder is, by weight, about about 54% Ni, about 32~ Cr, about 13.5% Al, about 0.8 Y, and incidental elements which do not adversely affect the alloy powder.
The heat treatment substantially homogenizes the metal matri~ 18 surrounding abrasive particles 20, so that the composition of metal matri~ 18 after heat treatment is, by weight, ahout 31-33% Ni, about 19-22% Cr, about 7-9% Al, about 0.35-0.65~ Y, and the balance Co and small amounts of incidental elements which do not adversely affect the alloy.
$ ~ ~
PATE~T
13DV-993s After appl~cation of a first cobalt thin layer 36 by electrodeposition and fine CoNiCr~lY powders in a second cobalt layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on th~
tip of a Rene' N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 1975-2050F. The metal composition is initially essentially 100~ Co and incidental elements which do not adveræely affect the alloy, while the composition of the fine prealloyed powder is, by weight, about about 54% Ni, about 32% Cr, about 13.5~ Al, about 0.8 Y, and incidental elements which do not adversely affect the alloy powder.
The heat treatment substantially homogenizes metal matris 18 surrounding the abrasive particles, so that the composition of metal matris 18 after heat treatment is, by weight, about 31-33% Ni, about 19-22~ Cr, about 7-9% Al, about 0.35-0.65% Y, and the balance Co and small amounts of incidental elements which do not adversely affect the alloy.
After application of a first cobalt thin layer 36 by eleçtrodeposition, and fine powders having a composition by weight of about 20% Co, 10.2% Al, 10.7~ Ta, 11.3 % Cr, 2.5% Hf, 4.7% Re, 0.2% C, 8.3% W and the balance Ni and incidental impurities in a second nickel layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on the tip of a Rene~ N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 2000-2075F. This heat treatment substantially homogenizes metal matris 18, thin layer 36 and the fine powder so that the composition of the metal matris after heat treatment is the composition of Rene' 142, Table 1.
2 ~ 8 0 4 PATENT
13DV-9g3s ~Xa~PLE 4 After application of a first cobalt thin layer 36 by electrodeposition, and fine powders having a composit~on by weight of about 6.7~ Co, 10% Al, 8.3% Ta, 15~ Cr, 1.5%
Hf, 2.5~ Mo, 2.3~ Re, 0.03~ Zr and the balance ~i and incidental impurities in a second nickel layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on the tip of a Rene' N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 2000-2075F. The heat treatment substantially homogenizes metal matris 18, thin layer 36 and the fine powder so that the composition of the metal matri2 after heat treatment is the composition of PS6MY, see Table 1.
After application of a first cobalt thin layer by electrodeposition and fine powders Xaving a composition by weight of about 16.7% Co, 10.8~ Al, 10% Ta, 30~ Cr, 0.83%
Hf, 3.3% Re, 0.07% C, 0.02% Zr and the balance Ni and incidental impurities in a second nickel layer by co-electrodeposition over the first thin layer, thereby surrounding abrasive particles 20 on the tip of a Rene' N5 turbine blade, the blade is heat treated in an inert gas atmosphere or vacuum for about 2-4 hours at about 2000-2075F. This heat treatment substantially homogenizes metal matris 18, thin layer 36 and the fine powders so that the composition of the metal matris after heat treatment is the composition of ~C-53, see Table 1.
2 0 ~ L~ PATENT
Table 1 Nominal Composition PS6MX Rene' 142 BC-53 Ni Bal. Bal. Bal.
Co 4 12 10 Al 6 6.1 6.5 Ta 5 6.4 6 Cr 9 6.76 18 Hf 0.9 1.49 O.S
Mo 1.5 --- 0 Re 1.4 2.84 2.0 C 0 .11 0.05 Zr 0.02 --- 0.01 lS W ___ 5 While the process of the present invention eliminates the necessity for providing coated abrasive particles, if desired particles 20 may optionally be coated with a coating, such as a diffusion barrier coating, prior to placing the particles in contact with adhesive layer 32.
However, it is preferred to use nonconductive and nonsilicon-bearing particles, such as alumina (~12O3).
' : :
-20i~8~
PATENT
13~V-9935 Because the smbodiment of the in~ention shown in Fig. 1 is thin, be~ng comprised of a single layer of abrasive particles 20 emb2dded in a metal matri~
18, it is espected that abrasive tip 16 will be removed from tip 14 of blade lO in a relatively short time as compared to overall blade life. In such a case, it may be desirable to optionally coat tip 14 with an environmentally resistant material prior to application of the abrasive tip. In such a case, the abrasive tip is applied by the process of the present invention over the environmentally resistant material, in which case the environmentally resistant material is substituted for the substrate in the above description of the invention. A commonly used environmentally resistant material has a nominal composition of, by weight, of about 33% Ni, about 23%
Cr, about 4% Al, about 0.5~ C, about 3% W, about 33%
Co, about 3% ~a, about 0.75% Si. along with incidental impurities. This composition is described in U.S. Pat. No. 4,227,703 issued Oct. 14, 1980, which is hereby incorporated by reference. ~owever, this environmentally resistant undercoat is provided by way of esample, and is not meant to limit application of the long life abrasive tip of the present invention solely over this environmentally resistant undercoat. A turbine blade having an environmentally resistant layer 44 overlaying tip 14 is shown in Fig. 8.
If early removal of the thin abrasive tip is undesirable during engine operation, the method of the present invention can be used to apply multiple layers of particles, so that even if the initial layer of particles is worn off the tip, additional layers of particles remain so that additional 2 0 ~1 ~ 8) ~ L~ ~3DY-9935 material can be abraded from the shroud, if necessary, Referring now to Fig. 9, n turbine blade 80 having an abrasive tip 82 with two rows of abrasive particles, 8~ and 86 embedded in a m~tal matri~ 88 i~ depicted. Abrasive particles 84 ~n the layer ~losest to blade tip 90 ar~ coplanar an~
parallel to the plane of abrasive particles 86 forming the layer furthest from blade tip 90.
Although particles 84 and 86 are shown as being about the same size, it may be desirable to size the particles such that particles 86 are larger, which is desirable during three-body-abrasive wear which occurs early in engine operation, while particles 84, which are smaller, will remain after the layer containing particles 86 has worn away. The smaller particles in the layer closer to the tip will be more effective during the adhesive wear phases which may occur during later stages of engine operation.
In light of the foregoing discussion, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments, methods and compositions herein described. Numerous modifications, changes, substitutions and equivalents will now become apparent to those skilled in the art, all of which fall within the scope contemplated by the invention.
Claims (25)
1. A method for applying an abrasive layer to a metallic substrate, the abrasive layer comprised of abrasive particles in a metal alloy matrix comprising the steps of :
(a) selecting abrasive particles of about size and shape to maximize volume content of the particles;
(b) physically contacting the abrasive particles to the substrate surface;
(c) while maintaining the particles in contact with the substrate surface, depositing a first thin layer of metal onto the substrate surface, thereby adhering the abrasive particles to the substrate surface;
(d) applying a second metal containing fine prealloyed powders by co-electrodeposition over the abrasive particles and the first thin layer of metal; and, (e) thermally treating the abrasive-layered substrate to homogenize the first thin layer of metal and the second metal containing prealloyed powders to form a substantially homogeneous metal alloy matrix.
PATENT
(a) selecting abrasive particles of about size and shape to maximize volume content of the particles;
(b) physically contacting the abrasive particles to the substrate surface;
(c) while maintaining the particles in contact with the substrate surface, depositing a first thin layer of metal onto the substrate surface, thereby adhering the abrasive particles to the substrate surface;
(d) applying a second metal containing fine prealloyed powders by co-electrodeposition over the abrasive particles and the first thin layer of metal; and, (e) thermally treating the abrasive-layered substrate to homogenize the first thin layer of metal and the second metal containing prealloyed powders to form a substantially homogeneous metal alloy matrix.
PATENT
2. A method for applying an abrasive layer to a substrate, the abrasive layer comprised of at least one discrete layer of environmentally resistant abrasive particles in a metal matrix, the abrasive particles in a discrete layer being coplanar, comprising the steps of:
(a) selecting abrasive particles of approximately the same size and shape;
(b) physically contacting the abrasive particles to the substrate surface;
(c) while maintaining the particles in physical contact with the substrate surface, depositing a first thin layer of metal onto the substrate surface, thereby adhering the abrasive particles on the substrate surface;
(d) applying a second metal containing fine prealloyed powders by co-electrodeposition over the abrasive particles and the first thin layer of metal; and (e) heat treating the substrate to homogenize the first thin layer of metal and the second metal containing prealloyed powder to form a homogeneous uniform metal matrix.
(a) selecting abrasive particles of approximately the same size and shape;
(b) physically contacting the abrasive particles to the substrate surface;
(c) while maintaining the particles in physical contact with the substrate surface, depositing a first thin layer of metal onto the substrate surface, thereby adhering the abrasive particles on the substrate surface;
(d) applying a second metal containing fine prealloyed powders by co-electrodeposition over the abrasive particles and the first thin layer of metal; and (e) heat treating the substrate to homogenize the first thin layer of metal and the second metal containing prealloyed powder to form a homogeneous uniform metal matrix.
3. The method of claim 2 wherein the step of physically contacting the abrasive particles to the substrate surface further comprises:
applying the abrasive particles to a surface of a material having an adhesive layer;
removing excess abrasive particles from the adhesive layer;
PATENT
placing the abrasive particle containing adhesive layer against the substrate surface so that the abrasive particles contact the substrate surface;
and maintaining the abrasive particles in contact with the substrate surface.
applying the abrasive particles to a surface of a material having an adhesive layer;
removing excess abrasive particles from the adhesive layer;
PATENT
placing the abrasive particle containing adhesive layer against the substrate surface so that the abrasive particles contact the substrate surface;
and maintaining the abrasive particles in contact with the substrate surface.
4. The method of claim 2 wherein the step of selecting abrasive particles further includes selecting approximately cubic-shaped abrasive particles having a minimum edge dimension of about 2 mils and a maximum edge dimension of about 15 mils.
5. The method of claim 4, wherein the aspect ratio of the abrasive particles is about 1.
6. The step of claim 5 further including selecting approximately cubic-shaped abrasive particles having an edge dimension of about 5 to about 6 mils.
7. The step of claim 5 wherein the step of selecting abrasive particles further includes selecting abrasive particles made by the sol-gel process.
8. The method of claim 2 wherein the step of depositing the first thin metal layer includes electroplating the first thin metal over the substrate surface.
PATENT
PATENT
9. The method of claim 2 wherein the step of depositing the first thin metal layer includes electroless plating the first thin metal over the substrate surface.
10. The method of claim 2 wherein the step of depositing the first thin metal layer further includes depositing the first thin layer of metal selected from the group consisting of Ni and Co onto the substrate surface to a thickness of about 0.1 to about 0.6 mils.
11. The method of claim 3 wherein the step of selecting abrasive particles includes selecting approximately cuboidal alumina particles having an edge size of about 0.005 to about 0.006 inches.
12. The method of claim 2 further including the step of encapsulating the abrasive particles with a diffusion barrier coating after the step of selecting abrasive particles and before the step of contacting the particles to the substrate surface.
13. The method of claim 2 wherein the step of depositing a second metal further includes co-electrodepositing a second metal solution having fine prealloyed powder particles.
14. The method of claim 12 wherein the step of co-electrodepositing includes co-electrodepositing a second metal selected from the group consisting of nickel, and cobalt and the fine prealloyed powder is selected from the group consisting of NiCrAlY, CoNiCrAlY and CoCrAlY.
PATENT
PATENT
15. A method for applying an abrasive tip to a turbine blade having a first end adapted for attachment to a turbine disk, and a second tip end, the abrasive tip comprised of at least one discrete layer of oxidation-resistant and corrosion-resistant abrasive particles in a metal alloy matrix, the particles in a discrete layer being coplanar, comprising the steps of :
(a) selecting abrasive particles of approximately the same size and shape;
(b) applying the abrasive particles to a surface of a layer of felt having an adhesive;
(c) removing excess abrasive particles from the surface of the layer of felt having the contact adhesive;
(d) placing the tip end of the turbine blade in physical contact with the abrasive particles adhering to the layer of felt having the adhesive;
(e) securing the felt to the tip end of the turbine blade;
(f) immersing the tip end of the turbine blade in an electroplating bath;
(g) while maintaining the abrasive particles in mechanical contact with the the turbine blade tip end, electroplating a first thin layer of metal onto the tip end of the turbine blade, thereby causing the abrasive particles to adhere to the tip end of the turbine blade;
(h) removing the layer of felt;
(i) applying a solution of a second metal containing fine prealloyed powder particles by co-electrodeposition over the abrasive particles and the first thin layer of metal on the substrate surface; and PATENT
(j) heat treating the blade so as to homogenize the first thin layer of metal and the second metal containing fine prealloyed powder particles to form a substantially homogeneous metal matrix.
(a) selecting abrasive particles of approximately the same size and shape;
(b) applying the abrasive particles to a surface of a layer of felt having an adhesive;
(c) removing excess abrasive particles from the surface of the layer of felt having the contact adhesive;
(d) placing the tip end of the turbine blade in physical contact with the abrasive particles adhering to the layer of felt having the adhesive;
(e) securing the felt to the tip end of the turbine blade;
(f) immersing the tip end of the turbine blade in an electroplating bath;
(g) while maintaining the abrasive particles in mechanical contact with the the turbine blade tip end, electroplating a first thin layer of metal onto the tip end of the turbine blade, thereby causing the abrasive particles to adhere to the tip end of the turbine blade;
(h) removing the layer of felt;
(i) applying a solution of a second metal containing fine prealloyed powder particles by co-electrodeposition over the abrasive particles and the first thin layer of metal on the substrate surface; and PATENT
(j) heat treating the blade so as to homogenize the first thin layer of metal and the second metal containing fine prealloyed powder particles to form a substantially homogeneous metal matrix.
16. The method of claim 15 further including the step of encapsulating the abrasive particles with a diffusion barrier coating after the step of selecting the abrasive particles and before the step of applying the particles to a surface of a layer of felt.
17. The method of claim 15 further including a step of coating the tip end of the turbine blade with an environmentally resistant material prior to the step of placing the tip end of the blade in contact with the abrasive particles.
18. The step of claim 15 wherein the step of selecting abrasive particles includes selecting approximately cuboidal-shaped abrasive particles having a minimum edge dimension of about 5 to about 6 mils and wherein the abrasive particles are made by the Sol-Gel process.
19. The method of claim 15 wherein the step of electroplating includes electroplating a metal selected from the group consisting of cobalt and nickel.
20. The method of claim 15 wherein the step of applying a second metal includes applying a second metal compatible with the first electroplated metal.
PATENT
PATENT
21. The method of claim 15 wherein the step of applying a second metal includes applying a metal selected from the group consisting of Ni and Co, and wherein the fine prealloyed powder particles are selected from the group consisting of NiCrAlY, CoNiCrAlY and CoCrAlY.
22. A method for applying an abrasive tip to a turbine blade having a tip end, the abrasive tip comprised of at least one discrete layer of environmentally resistant abrasive particles in a Rene' 142 metal matrix of the abrasive particles in a discrete layer being coplanar, comprising the steps of:
(a) selecting abrasive particles having about the same aspect ratio;
(b) physically contacting the abrasive particles to the tip end of the turbine blade;
(c) while maintaining the particles in physical contact with the tip end of the turbine blade, depositing a thin layer of Co onto the blade tip end, thereby adhering the abrasive particles to the tip surface;
(d) co-electrodepositing a solution of Ni and fine pre-alloyed powders over the abrasive particles and the layer of Co, the fine pre-alloyed powders selected so that after substarted homogenization the metal matrix is Rene' 142.
(e) heat treating the blade to substantially homogenize the prealloyed powder and Ni to form a Rene' 142 matrix.
PATENT
(a) selecting abrasive particles having about the same aspect ratio;
(b) physically contacting the abrasive particles to the tip end of the turbine blade;
(c) while maintaining the particles in physical contact with the tip end of the turbine blade, depositing a thin layer of Co onto the blade tip end, thereby adhering the abrasive particles to the tip surface;
(d) co-electrodepositing a solution of Ni and fine pre-alloyed powders over the abrasive particles and the layer of Co, the fine pre-alloyed powders selected so that after substarted homogenization the metal matrix is Rene' 142.
(e) heat treating the blade to substantially homogenize the prealloyed powder and Ni to form a Rene' 142 matrix.
PATENT
23. A method for applying an abrasive tip to a turbine blade having a tip end, the abrasive tip comprised of at least one discrete layer of environmentally resistant abrasive particles in a PS6MY metal matrix, the abrasive particles in a discrete layer being coplanar, comprising the steps of:
(a) selecting abrasive particles having about the same aspect ratio;
(b) physically contacting the abrasive particles to the tip end of the turbine blade;
(c) while maintaining the particles in physical contact with the tip end of the turbine blade, depositing a thin layer of Co onto the blade tip end, thereby adhering the abrasive particles to the tip surface;
(d) co-electrodepositing a solution of Ni and fine pre-alloyed powders over the abrasive particles and the layer of Co, the fine pre-alloyed powders selected so that after substarted homogenization the metal matrix is PS6MY.
(e) heat treating the blade to substantially homogenize the prealloyed powder and Ni to form a PS6MY matrix.
(a) selecting abrasive particles having about the same aspect ratio;
(b) physically contacting the abrasive particles to the tip end of the turbine blade;
(c) while maintaining the particles in physical contact with the tip end of the turbine blade, depositing a thin layer of Co onto the blade tip end, thereby adhering the abrasive particles to the tip surface;
(d) co-electrodepositing a solution of Ni and fine pre-alloyed powders over the abrasive particles and the layer of Co, the fine pre-alloyed powders selected so that after substarted homogenization the metal matrix is PS6MY.
(e) heat treating the blade to substantially homogenize the prealloyed powder and Ni to form a PS6MY matrix.
24. A method for applying an abrasive tip to a turbine blade having a tip end, the abrasive tip comprised of at least one discrete layer of environmentally resistant abrasive particles in a BC-53 metal matrix, the abrasive particles in a discrete layer being coplanar, comprising the steps of:
PATENT
(a) selecting abrasive particles having about the same aspect ratio;
(b) physically contacting the abrasive particles to the tip end of the turbine blade;
(c) while maintaining the particles in physical contact with the tip end of the turbine blade, depositing a thin layer of Co onto the blade tip end, thereby adhering the abrasive particles to the tip surface;
(d) co-electrodepositing a solution of Ni and fine pre-alloyed powders over the abrasive particles and the layer of Co, the fine pre-alloyed powders selected so that after substarted homogenization the metal matrix is BC-53.
(e) heat treating the blade to substantially homogenize the prealloyed powder and Ni to form a BC-53 matrix.
PATENT
(a) selecting abrasive particles having about the same aspect ratio;
(b) physically contacting the abrasive particles to the tip end of the turbine blade;
(c) while maintaining the particles in physical contact with the tip end of the turbine blade, depositing a thin layer of Co onto the blade tip end, thereby adhering the abrasive particles to the tip surface;
(d) co-electrodepositing a solution of Ni and fine pre-alloyed powders over the abrasive particles and the layer of Co, the fine pre-alloyed powders selected so that after substarted homogenization the metal matrix is BC-53.
(e) heat treating the blade to substantially homogenize the prealloyed powder and Ni to form a BC-53 matrix.
25. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60796890A | 1990-11-01 | 1990-11-01 | |
| US607,968 | 1990-11-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2048804A1 true CA2048804A1 (en) | 1992-05-02 |
Family
ID=24434463
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2048804 Abandoned CA2048804A1 (en) | 1990-11-01 | 1991-08-08 | Long life abrasive turbine blade tips |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0484115A1 (en) |
| JP (1) | JPH04285198A (en) |
| CA (1) | CA2048804A1 (en) |
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| US10822967B2 (en) | 2017-02-01 | 2020-11-03 | Raytheon Technologies Corporation | Wear resistant coating, method of manufacture thereof and articles comprising the same |
| IT201900003691A1 (en) | 2019-03-13 | 2020-09-13 | Nuovo Pignone Tecnologie Srl | Abrasive terminal of a rotor blade for a turboexpander |
| US11299993B2 (en) | 2019-10-28 | 2022-04-12 | Honeywell International Inc. | Rotor assembly for in-machine grinding of shroud member and methods of using the same |
| US11713681B1 (en) | 2022-05-18 | 2023-08-01 | Raytheon Technologies Corporation | Fan blade repair systems and methods |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3980549A (en) * | 1973-08-14 | 1976-09-14 | Di-Coat Corporation | Method of coating form wheels with hard particles |
| JPS5415535B2 (en) * | 1973-08-31 | 1979-06-15 | ||
| US4744725A (en) * | 1984-06-25 | 1988-05-17 | United Technologies Corporation | Abrasive surfaced article for high temperature service |
| US4608128A (en) * | 1984-07-23 | 1986-08-26 | General Electric Company | Method for applying abrasive particles to a surface |
| GB2167446B (en) * | 1984-10-05 | 1988-05-05 | Baj Ltd | Electrode deposited composite coating |
| IT1224259B (en) * | 1984-10-05 | 1990-10-04 | Baj Ltd | IMPROVEMENT IN METAL PROTECTIVE COATINGS AND PREPARATION PROCEDURE |
| US4818833A (en) * | 1987-12-21 | 1989-04-04 | United Technologies Corporation | Apparatus for radiantly heating blade tips |
| GB2241506A (en) * | 1990-02-23 | 1991-09-04 | Baj Ltd | Method of producing a gas turbine blade having an abrasive tip by electrodepo- sition. |
-
1991
- 1991-08-08 CA CA 2048804 patent/CA2048804A1/en not_active Abandoned
- 1991-10-28 JP JP30724691A patent/JPH04285198A/en active Pending
- 1991-10-30 EP EP91309998A patent/EP0484115A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0484115A1 (en) | 1992-05-06 |
| JPH04285198A (en) | 1992-10-09 |
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