JPH0555295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to abrasive bodies (hereinafter referred to as abrasives) in abrasive seals, and in particular to thin layer abrasive bodies deposited on superalloys used at elevated temperatures. Related.

BACKGROUND OF THE INVENTION Gas turbine engines and other axial flow turbomachines have rows of rotating blades contained within a generally cylindrical case. It is highly desirable to minimize leakage of gas or other working fluid around the blade tips close to the case. It is known that this leakage is minimized by blade and sealing systems in which the blade tips rub against seals mounted on the interior surface of the engine case. in general,
The blade tips are made harder and more abrasive than the seals, so that the blade tips cut into the seals as they contact each other during operation of these parts of the engine.

In previous systems of the type described above, the blade tip was often a superalloy material with a hard surface;
The seal was a metal with a reasonable tendency to wear.
For example, porous powdered metals were used. Now, however, seals comprising ceramics have been found desirable, as shown in U.S. Pat. Nos. 3,975,165, 4,269,903 and 4,273,824. Ceramic coated seals are considerably harder than conventional metal seals, and as a result, conventional blade tips lack the ability to abrade the seals.

Accordingly, an improved blade tip is described, most particularly in U.S. Pat. A type of blade tip has been developed. Silicon carbide particles of average standard diameter of 0.20 to 0.76 mm according to this patent are coated with metal oxides such as alumina and incorporated into nickel or cobalt based alloys by powder metal or casting techniques. Particles with a volume percentage of 30-45% containing powdered metal compactly are manufactured and diffuse bonded to the tip of the blade,
Bonded by liquid phase bonding or brazing.

However, abrasives produced by the above method have some inherent properties. especially,
Metal parts have a minimum practical thickness, typically 1 to
It can only be manufactured in a thickness of 2 mm. Typically, abrasive tips are manufactured to the cross-sectional shape of the tip of a turbine blade body and machined into a flat surface after compaction or casting. Similarly, the blade tip is machined into a flat surface to accept the abrasive. Such flat machining is a necessary practical limitation to obtain a good close fit and minimum weld thickness on the order of 0.05 mm. If this is not done, adequate bond strength at operating temperatures of 1100°C will not be achieved. After bonding the abrasive onto the blade tips, the plurality of blades are assembled into a fixture configured to rotate with the engine disk. They are then ground to a cylindrical or conical surface that matches the inner surface of the engine case seal. As a result of this process, the abrasive initially has a substantial thickness that must be ground to a substantial degree. Particles are often expensive and therefore the method is also expensive. Second, because the mating surface is flat and the final finished shape of the abrasive-tipped blade is cylindrical or conical, the thickness of the abrasive can be reduced across the blade tip, as shown in Figure 9. Change exists. Although known blades are useful, it is more desirable for the abrasive portion of the tip to have a uniform thickness across the curve. It is also highly desirable to minimize the amount of grit that must be used during the manufacturing process. This is because the grits must be of high quality and their manufacture, including the oxide coating process, is expensive.

It is an object of the present invention to form a thin, uniform layer of abrasive on the tip of the blade that is suitable for use at temperatures near and above 1100°C. Abrasive thin layers carrying particles are known, although they are not suitable for use at such high temperatures. For example, coated abrasives made from alumina, silica and silicon carbide are common products, as are metal bonded diamond and cubic boron nitride grinding wheels. Sprayed molten or unfused layers of metal are well known in the metallization art. See, eg, US Pat. Nos. 3,248,189 and 4,386,112.
However, both metal spraying grit and base metal processes are inherently inadequate in that only a portion of the sprayed material actually impacts and adheres to the surface. These particularly make the abrasive formation of typical turbine blade tips of relatively small size, for example about 6/50 mm, difficult.

The prior art particularly relevant to the present invention is as follows. Silicon carbide particles are described in U.S. Patent No.
According to Nos. 3,508,890 and 3,377,624, parts are bonded using organic adhesives and then surface coated with aluminum or other metals. US Patent No.
No. 3,779,726 discloses a method of manufacturing metal abrasive tools containing silicon carbide and other grits by encapsulating the grit in a porous metal coating and then using an encapsulation layer with another metal to integrate the particles. A method of impregnation is described. U.S. Pat. No. 4,029,852 describes a method for producing a non-skid surface by placing grit on the surface and spraying droplets of molten metal thereon. The invention of this US Patent No. 4,029,852 is
In contrast to the metal bonded abrasives and the fine products that characterize this invention, relatively large products such as stair treads are targeted. U.S. Pat. No. 3,871,840 describes how the properties of metal bonded abrasives made in various ways are improved by encapsulating grit within a pure metal envelope.

The previously described abrasives, which are comprised of particles and metal structures and are attached to turbine blade tips by a welding process, have exhibited useful abrasive properties. However, although it is desirable to reduce the abrasive thickness to the minimum thickness required for a robust tip, such minimum thickness may be limited for some bonded abrasive tips due to manufacturing practical issues discussed above. cannot be achieved. At the same time, past experience has shown that materials commonly available for other applications, including those described in the aforementioned U.S. patents, are insufficiently robust, even though they may provide the desired minimum thickness. Therefore, there was a need for research and development to produce superalloy turbine blades with the desired abrasive tips.

DISCLOSURE OF THE INVENTION An object of the present invention is to form a thin abrasive layer on the surface of a metal object. In particular, it is an object of the present invention to form a very lightweight yet robust abrasive material on airfoil for turbomachinery. That is, it is desirable to produce ceramic particles and metal abrasives using as few particles as possible. For high temperature applications, the abrasive must be made of oxidation-resistant materials, especially superalloy base metals, and the abrasive must be well bonded to the superalloy substrate to withstand thermal and mechanical stresses. It won't happen.

According to the invention, the article has a single layer of ceramic particles on its surface. The particles are in contact with the surface of the substrate and extend predominantly through the surrounding base metal to the free machined surface. Also, when the machined surface is parallel to the surface on which the abrasive is placed, the particles have equal lengths and are placed on the surface in the most effective manner. To obtain optimal performance from the abrasive, the particles are closely but evenly spaced. However, the particles are carefully sized and arranged so that at least 80% do not touch each other.
Thus, the presence of a surrounding matrix means that the particles are better bonded within the abrasive, and the abrasive is better bonded to the substrate. Abrasives according to the invention are made from ceramics having a particle aspect ratio of less than 1.9:1, preferably around 1.5:1. This allows the particles to be present at approximately even spacing with a density of 33 to 62, preferably 42 to 53 per cm ² of the particle surface, and also in 10 to 20 (volume percentage).

In a preferred embodiment of the invention, abrasive materials are applied to the tips of superalloy turbine blades using sintering, plasma arc spraying, and machining. Ceramic particles do not interact with the matrix material at elevated temperatures. For example, alumina-coated silicon carbide particles have been used. The particles were further clad with a sinterable material, such as nickel. The particles are placed on the surface and heated to a sintering temperature, thereby alloyingly adhering the nickel layer to the substrate. The superalloy matrix is then typically deposited in a “line of sight” process (where the deposited material moves in a straight line towards the surface).
deposited onto the particles by Cavities are created near the irregularly shaped particles on the surface and a process such as hot static pressing is then used to densify the matrix around the particles. The result is a dense superalloy matrix containing ceramic particles with regions of interdiffused metal at the periphery (relatively deficient in the composition of the matrix material and regions relatively rich in the composition of the cladding material). A metallurgical structure is obtained which can be attached.

When the abrasive is placed on the tip of the blade that interacts with the ceramic seal, the base material
The free machined surface of the abrasive is partially removed to expose 10-50% of the particle length as measured from the substrate. This improves the abrasive's ability to cut ceramic seals.

The present invention utilizes a relatively small cambered surface on the airfoil tip to protect the blade tip from wear, cut into a ceramic anti-friction seal, and withstand high temperatures and thermal stresses. It is effective in depositing abrasive materials to achieve this goal.

The above and other objects, features and advantages of the present invention will become more apparent as preferred embodiments thereof are described in detail below with reference to the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a simple introduction to the tips of a typical advanced gas turbine engine turbine blade consisting of a single crystal nickel alloy as described in U.S. Pat. No. 4,209,348. describes the bonding of silicon carbide particles called "abrasives" and superalloy matrix abrasives. Preferably, alumina-coated silicon carbide particles of the type disclosed in US Pat. No. 4,249,913 are used in the present invention. The disclosures of both of the above patents are incorporated herein by reference. The invention is equally applicable to other materials. The above U.S. patent no.
Alumina coatings on silicon carbide particles, as shown in US Pat. No. 4,249,913, are particularly useful because they prevent interaction between the silicon carbide and the surrounding base metal. Such interactions can occur during manufacturing and high temperature use and can reduce the ability of the silicon carbide particles to perform abrasive functions. Preferably the alumina coating is 0.010-0.020mm
thickness and is deposited by a commercial chemical vapor deposition process.

The matrix is a metal that can be bonded to the particles and the substrate. The base material, in the best embodiment of the invention, is a high-temperature alloy, i.e., Inconel, a commercial alloy.
600, Inconel 625, Hastelloy X, Haynes
Alloys or superalloys suitable for use at temperatures of 600°C or above, such as 188 and MCrAlY, i.e. commercial nickel-based alloys such as Waspaloy, IN100, U700, MAR-M200, Inconel 718. This is an alloy with a base material of Ni, Co or Fe that has been strengthened by gamma prime precipitation. Alloys of either type tend to have a number of compositions with varying properties, namely Ni, Co, Fe, Cr and Fe, with the latter two elements particularly distinguishing them and resulting in oxidation resistance.

Preferably, the superalloy matrix has a weight percentage of 21 to
25Cr, 4.5~7Al, 4~10W, 2.5~7Ta, 0.02~
It has a standard composition of 0.15Y, 0.1~0.3C, and residual Ni.
Other useful materials are 18~30Cr, 10~
30Ni+Fe, 5~15W+Mo, 1~5Ta+Cb, 0.05
~0.6C, 3.5~80Al, 0.5~20Hf and 0.02~0.1Y,
It is a cobalt-based alloy with a standard composition of residual Co.

A typical turbine blade configuration is shown in FIG. The blade 20 consists of a root section 22 and an airfoil section 24. An abrasive layer 26 is applied to the blade tip 28 by the method of the present invention. The surface 30 of the abrasive tip is finished as a rotating cylindrical surface with a standard radius R and a circumference D. Radius R is the radius of the bladed turbine wheel and is also the inner radius of the engine case that typically contains the bladed turbine wheel. The blade axis that coincides with the radial direction is defined as its z-axis. The tip of the blade has an average camber line C, which is the standard centerline of the Aerofoil tip cross section. 9 and 10 show a side view of the blade tip as it appears when looking along line D towards line C when line C is expanded into the z-plane. FIG. 10 shows the appearance of the constant thickness layer 26 of FIG. Both the outermost surface 32 of the blade substrate 28 and the abrasive surface 30 are curved. These curved surfaces are complex due to the surface defined by the interaction of the cambered and cylindrical surfaces when stretched. A similar view of a known blade tip constructed in the manner described in the background section is shown in FIG. The outermost surface 30a of the abrasive is the curved surface 3 shown in FIG.
0, and the surface 32 of the blade base 28a
a is flat. Therefore, the radial or z-axis abrasive thickness varies across the camber length C of the airfoil. There is also a clear tendency for metal-poor grit to be present at the leading and trailing edges. Also, in accordance with the present invention, in FIG. 10, the abrasive consists of a single layer of particles, whereas the known layer requires a large number of grits near the central portion 35a of the camber line length. Also, known abrasives typically have adhesive seams 31.

The process steps for forming a thin abrasive tip are partially outlined in FIGS. 1-7 and described further below. 1-4 show the profile of the tip of a gas turbine blade, and FIGS. 5-7 show a portion of the tip in more detail, both viewed along line D.

The abrasive tip of the present invention is intended to interact with abradable seals by abrasion of ceramics, as disclosed in a few of the US patents mentioned in the background section. There are several unique aspects of the abrasive that have been discovered to be necessary for good performance and that differ from known advanced abrasives. These aspects are the composition of the particles and matrix, the dimensions of the particles,
Density placed at the tip of the blade (both in terms of spacing and volume percentage when contained within the matrix)
, the total thickness of the abrasive layer, and the degree to which the particles are actually enveloped by and placed within the matrix. The parametric limitations advocated herein are particularly the result of experience with abrasives containing a superalloy matrix and alumina-coated silicon carbide particles as disclosed in U.S. Pat. No. 4,249,913. However, many of the aspects are also suitable for other particles, especially those relating to mechanical aspects.

Abrasive thickness must be limited and must follow particle sizing. First, abrasives include a single layer of particles as shown in FIG. A single layer of abrasive particles is important to keep the mass of abrasive material at the tip to a minimum.
Empirical tests and calculations have shown that in order for an abrasive tip to work effectively when interacting with a ceramic seal, i.e. to ensure that particles are properly cut and not easily removed from the blade tip. It has been found that approximately 10-50% of the matrix must be removed. If more is removed, the remaining matrix will be insufficient to hold the particles under the loads during use.

AZ of preferred tip abrasive according to the present invention
The axial thickness is approximately 0.38 ± 0.03 mm, and for such a thickness, the particle size is US sieve series No. 35-40.
(typically 0.42±0.50mm). Of course, even a common sieve will result in a distribution of particle sizes, especially since typical ceramic particles are irregular. Some of the particles are smaller than the No. 40 sieve size. However, the standard minimum particle size is 0.42 mm, which means that the majority of ceramics (0% or more
This reflects the fact that the free surfaces 44, 30 of the abrasive necessarily extend through the matrix as shown in FIGS. 4 and 9. This is in contrast to the prior art shown in FIG. 9 and the previously referenced patents. When a thicker abrasive layer is desired, a US sieve series No. 20 (typically 0.83 mm) is used to obtain the desired result.
It has been found effective to use larger particles up to .

Typically, the matrix is deposited to a sufficient thickness to surround the particles, and the matrix and particle composite is then machined to finished dimensions. Thus, a majority of the particles have a machined length, and each particle is of equal length when the free surface is parallel to the substrate surface, which is the generally desirable aspect.

In the best embodiment of the invention, the particles are uniformly
Moreover, they are relatively densely spaced. The density is in the range of 33-62 particles per cm ² . nevertheless
More than 15-20% of the particles are not agglomerated, that is, they do not touch each other. Spacing between the particles is required for them to be properly surrounded by the matrix and properly adhered within the abrasive. In the present invention, the majority of the particles are completely surrounded by the matrix metal in a direction parallel to the surface (ie, transverse to the z-axis). This means that at least 80%, and typically 90%, of the particles are surrounded by the matrix, apart from the coarse particles exposed by the finish on the side edges of the tip. In order to obtain the above-mentioned composite with higher density and complete encapsulation,
The inventors have also found that hot pressed silicon carbide particles are less than 1.9:1, preferably about 1.4 to 1.5
I discovered that it must have a 1:1 aspect ratio. Aspect ratio is the standard ratio of a particle's longest axis to its standard cross-sectional dimension. The inventor of the present application is using a Quantimet Surface Analyzer (Cambridge Instrument Co., Ltd.).
Ltd., Cambridge, UK) to measure the aspect ratio. This aspect ratio is in contrast to the typical particles used in known powder metal abrasive tips, which have an aspect ratio of 1.9 to 2.1 to 1. For such particles, when the particles are placed on a surface by the manufacturing method shown in Figure 1, they are naturally placed with their longer lengths oriented approximately parallel to the surface;
Excessive agglomeration occurred. Such high aspect ratio particles tend to be less likely to adhere to a desired height than more equiaxed particles and also prevent high densities from being achieved.

As mentioned above, the particles are enclosed within the metal matrix. When the abrasive is machined into a flat surface as shown in Figure 3, prior to removal of a portion of the matrix, the particles typically account for about 10-20% of the total abrasive, preferably 15%. (volume percentage). This is a lower concentration than that disclosed in US Pat. No. 4,249,913. about
It has been found that concentrations above 20% tend to cause abrasive material fatigue due to cracking. Concentrations below 10% tend to produce unsuitable abrasive properties.

The critical dimensions, aspect ratios and densities mentioned above must be achieved in order to obtain the desired cutting action. Because the typical tip of a turbine blade is narrow, very few particles are present within this region. The object of the invention is to form a full line of particles across the width of the blade when viewed closely along line D in FIG. Due to the abrasive features of the present invention, this is achieved in 90% of the blades. The remainder may have a small number of open spaces due to particle loss between the time of depositing the particles on the part and the time the part is finally ready for use.

FIG. 1 shows how the particles are initially placed on the surface 32 of the substrate 28 to which they are subsequently to be permanently adhered. Prior to placing the silicon carbide particles on the surface, they were coated with a coating of 0.010 mm of evaporated alumina on their outside according to U.S. Pat. It is decorated with metal decoration. Methods for applying nickel coatings to ceramic particles are commercially available;
Also, U.S. Patent Nos. 3920410, 4291089 and
It is disclosed in the specification of No. 4374173. If the ceramic particles are inherently resistant to reaction with the matrix, a nalumina coating is not necessary.

Immediately before the particles are placed on the surface of the blade tip, a coating of polymeric adhesive is applied to the surface, which can be subsequently evaporated at a temperature below 540° C., to hold the particles after attachment. The inventor of this application has prepared 1 in toluene.
~20% (volume percentage) polystyrene was chosen.
Particles are placed on a surface by first drawing the particles into a perforated plate that is provided with a vacuum, then placing the plate on top of the surface and momentarily releasing the vacuum.
It will be clear that other methods and adhesives can be used to place the particles.

The blade with organic bonded particles is then heated. It is heated to at least 1000°C, typically about 1080°C, for 2 hours in a vacuum of about 0.06 Pa using a heating rate of about 500°C per hour in a vertical position. Other inert atmospheres may also be used. This process first vaporizes the polystyrene adhesive and then produces solid state bonding or sintering of nickel cladding on the surface of the blade.
The nature and location of the bond joint 34 can be observed in metallurgical micrographs after removal from the furnace, so
As shown in the figure. Because of the irregular shape of the particles and the thickness of the metal cladding on the particles, the bonds 34 are relatively delicate and are only placed at points where the particles 33 are very close to the surface 32. When the matrix is a superalloy, it is undesirable to have large amounts of bond metal around the particles or bond them to the blade substrate. It is also undesirable to expose the substrate to temperatures above about 1800 DEG C., thus limiting the selection of cladding on the particles to materials that will form a bond under such conditions. Additionally, the cladding material must be compatible with, and tend to interact with, the substrate and the subsequently deposited matrix. These conditions nevertheless allow a variety of materials to be used. Preferably nickel, cobalt or mixtures thereof are used. Alloying additives known to promote bonding may be included. Generally, the base metal of the cladding tends to be a metal from the transition series of the periodic table when a nickel, cobalt or iron based matrix and base alloy are included. Under certain circumstances,
A coating may be applied to surface 32 to enhance the desired adhesion.

The particles are then oversprayed with a layer of matrix material deposited by plasma arc spray to a thickness of approximately 1.1 to 1.3 mm as shown in FIGS. 2 and 6. Nickel-based superalloys such as those mentioned above, such as 25Cr, 8W, 4Ta by weight percentage:
A superalloy with a composition of 6Al, 1.0Hf, 0.1Y, 0.23C, and a balance of Ni is used.

-400 US sieve series mesh powder is deposited by argon helium plasma arc spray in a low pressure chamber. For example, Electro-Plasma Inc. (Irving, California, USA)
Commercially available equipment such as a 120kW low pressure plasma arc spray system can be used.
See also US Pat. No. 4,236,059. The blade is placed in a spray chamber evacuated to a pressure of 26 kPa or less. The oxygen level in the atmosphere is reduced to a level of 5 ppm by volume, for example, by contacting the atmosphere within the chamber with a reactive metal. The workpiece blade is placed in the plasma arc device such that the tip section is sprayed perpendicular to the axis of movement of the molten particles. The blade is suitably masked around its periphery to prevent stray spray from depositing on the sides of the blade.

Prior to the start of the actual deposition, the workpiece is simultaneously heated to at least 700°C, typically 850°C, by hot plasma arc gas, and at the same time as a ground electrode located in the vicinity of the plasma arc apparatus or as an integral part thereof. is made cathode with respect to the ground electrode. A current of about 70 A is applied to a typical turbine blade tip for about 2 to 10 minutes to help remove any oxide layer that may have built up on the component. The purpose of the heating process is to increase the receptivity of the part to plasma arc spray, also improve bonding, and further reduce residual stresses that exist after the workpiece, including the base metal and substrate, has cooled to room temperature. . The abrasive thus has improved resistance to cracking and spalling.

The metal matrix is 0.6-1.3 as shown
It is deposited to a thickness of 1.1-1.3 mm, preferably 1.1-1.3 mm. Preferably, the base metal is deposited by a physical process to a thickness and quality such that the layer of metal is impermeable to argon gas at elevated pressures, ie at least 130 MPa. This impermeability can be achieved with sufficient thickness of deposition by the plasma spray process described above. Although the layer is impermeable, the sixth
It is characterized by some porosity as shown in the figure. In particular, pores 38 are present in the material on the surface of the particles, and voids 40 are present adjacent many of the particles. Cavity 40 is characteristic of metal spray processes and is created by any "line-of-sight" deposition process or process in which the deposited material physically moves in a straight line. Other processes that may be used are physical vapor deposition processes. See US Pat. No. 4,153,005.

The part is then densified, preferably by hot isostatic pressing. Generally, this involves deforming the abrasive material past its yield or creep threshold at elevated temperatures. Preferably, the part is exposed to 1065° C. and 138 MPa argon pressure to close the holes and voids. Other hot pressing processes may be used to consolidate the matrix and to achieve densification and bonding purposes. After the base material is solidified, the part is cooled in the furnace and removed.

However, FIG. 7 shows in more detail how abrasive appears within a micrographically aligned sample. The superalloy matrix is dense and completely surrounds the particles. Surrounding each particle 33 is also a region 42 that is low in chromium, aluminum and heavier elements and rich in nickel compared to the composition of the base material. This is of course due to the nickel attached to the particles.
This is a result of the cladding layer and is a feature of the present invention.

The abrasive rough surface shown in FIG. 2 is then machined using conventional processes such as grinding to obtain the shape outlined in FIG. Free surface 44 creates the desired z-length dimension T' that characterizes the finished blade. next,
The blade surface 44 is contacted with an etchant or other substance that attacks the base material and removes a portion thereof. For example, electrochemical machining as described in US Patent Application No. 517,315, filed July 26, 1983, may be used.

As will be appreciated, the present invention includes particles that are aligned along the surface of the article. Such two-dimensional manufacturing methods yield much more uniform and effective abrasions than conventional three-dimensional manufacturing methods that are performed by mixing with metal powder and solidifying. In the present invention, the free machined abrasive surface is characterized by a relatively uniform cross-sectional area of the ceramic (reflecting the largest to smallest size). This is in contrast to the widely varying cross-sectional area reflecting the maximum-to-zero particle size that characterizes known powder metal abrasives. Also, when a portion of the matrix is partially removed, the presence of particulate material at the original free surface of the present invention remains unchanged. However, in the prior art, some of the particles were lost and the amount of free surface ceramic was reduced because part of the particles were only retained within the abrasive by the matrix from which the particles were removed.

Although the present invention has been described above with reference to specific preferred embodiments, it is understood that the present invention is not limited to these embodiments, and that various embodiments are possible within the scope of the present invention. will be clear to those skilled in the art.

[Brief explanation of the drawing]

Figures 1 to 4 outline the sequential process by which particles are placed on the surface of a substrate, encapsulated within a matrix, machined into a flat surface, and machined into a final form. be. FIG. 5 is a more detailed view of a portion of FIG. 1, showing how the particles appear after being metallically bonded to the surface of the substrate.
Figure 6 is a more detailed view of a portion of Figure 2, showing how the matrix surrounds the particles and also shows the "line of
FIG. 7 is a more detailed view of a portion of FIG. 2, which includes pores when a "site" deposition process is used. FIG. 7 is a more detailed view of a portion of FIG. 6 shows how the structure of FIG. 6 can be transformed. FIG. 8 is a schematic diagram of a typical gas turbine blade with an abrasive layer at the tip. FIG. 9 is a schematic diagram of a known abrasive blade tip. Figure 10 is a side view of the blade along line D of Figure 8, showing how the particles are present in a single layer; It shows how they extend slightly above the base material of the abrasive. 20...blade, 22...root portion, 24...
... Aerofoil portion, 26 ... Abrasive layer, 28 ... Tip, 30 ... Abrasive tip surface, 32 ... Outermost surface, 33 ... Particle, 34 ...
...Bond joining, 36...Superalloy base material, 38...
Hole, 40... void, 44... free surface.

Claims (1)

[Scope of Claims] 1. An article comprising a substrate, ceramic particles fixed to the surface of the substrate, and an abrasive layer made of a metal matrix, wherein most of the ceramic particles each have the above-mentioned abrasive layer in a first portion thereof. A second portion that is in contact with the surface of the substrate, crosses the layer of the metal base material from the first portion, and is exposed from the layer of the metal base material on the opposite side of the first portion. Articles characterized by: 2. A method of forming an abrasive layer on the surface of a substrate, wherein the ceramic particles are substantially attached to the surface of the substrate such that the majority of the ceramic particles are each in adhesive contact with the surface of the substrate at a first portion thereof. and applying the ceramic particles as a dispersed layer to the surface of the substrate in a manner that maintains the ceramic particles in contact with the surface of the substrate to form a metal matrix layer of sufficient thickness to just bury the ceramic particles. The step of forming a layer of a metal base material, the ceramic particles, the metal base material layer, and at least a surface portion of the base body by densifying the metal base material and applying a metallurgical method to the surface of the base body. A process of heating to a temperature sufficient to bond the ceramic particles to the substrate surface, and grinding the surface portion of the composite layer of the ceramic particles and the metal base material formed in this way, and grinding the ceramic particles on the side opposite to the first portion in contact with the substrate surface. A method characterized by comprising the step of: exposing the second portion from the layer of the metal base material. 3. In the method according to claim 2, each of the ceramic particles is preliminarily coated with a metal, and the metal base material is also metallurgically bonded to the metal coating of the ceramic particles during the heating process. A method characterized by: