JPS58130174A - Nitrogenated superhard composite body material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Background of the Invention Articles made from hard, heat resistant, and corrosion resistant materials serve many important applications.

Reactive sintering of a-silicon carbide and β-silicon carbide to produce high temperature resistant components is known, e.g., U.S. Arderson, US Pat. No. 2.93a.
No. 807 describes β-silicon carbide as an excellent binder.

Other useful components of these materials are superhard crystals such as diamond and cubic boron nitride. Their superior properties, such as hardness, have long been appreciated. For example, a satisfactory means of incorporating diamond into such materials would be highly beneficial and is an object of the methods and products of the present invention.

In the area of bonding diamond crystals, for example, the applicant's U.S. Pat.
Certain metals have been used in conjunction with the Houdres technique, as described in U.S. Pat.

Certain conventional methods were improved by published European Patent Application No. 43,541 by inventor John Michio Ohno, which is incorporated herein by reference.

The following patent application discloses a two-layer diamond composite with a special binder of β-silicon carbide. The binder holds the diamond crystals and binds the layers of the composite to form a matrix throughout the composite. The composite is formed by a method comprising the steps of: (a) forming a first dispersion of diamond crystals and carbon fibers in paraffin; (b) forming a first dispersion of diamond crystals and carbon fibers in paraffin; forming a second dispersion of fillers, fillers, and fillers; (C) compression molding said dispersions together to form an integral bilayer composite; and (d) substantially all of the halafins. (e) liquefying and penetrating the silicon into both layers; (f) soaking the layer of the composite with liquid silicon; and (b) bonding the composite and the infiltrated silicon under optical conditions to create a β-silicon carbide binder that binds the composite.

Cemented carbide crystals, such as diamond crystals and boron nitride crystals, are expensive items compared to carbide and other materials used in the cutting edges of metal cutting tools. Furthermore, the use of additional materials containing cemented carbide crystals increases the distribution of the crystals in the matrix in a narrow shim range, thus the majority of the crystals do not perform any cutting action. 0hno above
The method is known as the pressing and processing technique,
A method of isolating the crystals into defined areas, such as discs and triangles, is provided, thus the overall amount of cemented carbide crystals is reduced.

03) Summary of the Invention Now, a compression molded body in which cemented carbide crystals are concentrated in small lumps in a predetermined and multi-spacing relationship is produced by subjecting the compression molded body to a nitriding process and an infiltration step to obtain nine silicon elements. It was discovered that the structure can be improved by converting it to silicon nitride. This improved nine methods include:
It is possible to produce high-strength cutting tool inserts in which the cemented carbide crystals in the predetermined positions are more discretely concentrated, for example in a triangular manner near the edge of the insert. These inserts use relatively little cemented carbide and are therefore relatively economical. Means are provided for attaching these unique inserts to a suitable tool holder.

(C) DESCRIPTION OF THE INVENTION The present invention will be better understood from the accompanying drawings and the following description.

The conjugate of the present invention can be made by the following steps.

(a) forming a first dispersion of carbide crystals and carbon bras in the halafin; (b) forming a second dispersion of carbon fibers, carbon bras, and filler in the halafin; and: (c) in order to produce a physically stable intermediate compression molded body (in the case of a diamond dispersion, a predetermined shape such as a cutting edge), one of the dispersions is pooled and the intermediate compression molded body is (e) subjecting the two compacts to a vacuum for a period of time at a temperature sufficient to evaporate substantially all of the paraffin; (f) recompression molding the dispersion of the liquid; Infiltrate the silicone into the compression molded body of two wrinkles; sintering the two series of compression molded bodies; and #subjecting the two series of compression molded bodies to nitriding treatment to convert the silicon element into silicon nitride.

As a result of this method, a composite is created that has an excellent wear-resistant surface layer. When diamond crystals are used, the diamond crystal-containing surface held tightly by a strong silica carbide bonding matrix is particularly suitable for tools or cutting edges.

The present method for making silicon carbide composites is representatively illustrated in FIG. As shown in the diagram, one of the first steps is the formation of a dispersion of diamond crystals and carbon plastic in paraffin. For various reasons, small crystals are usually used in this first dispersion. In a preferred embodiment, the diamonds used are crystals smaller than 400 Metzis in size. Crystals of this preferred size exhibit excellent resistance to chipping when bonded with β-silicon carbide. Additionally, they provide a gun cutting edge with a desired clearance angle for cutting inserts and other wear-resistant parts.

Carbon bra against diamond crystal.

Additional features must be added. This carbon, by subsequent reaction, yields β-silicon carbide for the bonding matrix of the composite. This carbon plastic is preferably of high purity, thus reducing the presence of contaminants. In particular, the ninth step is to prevent side effects in subsequent steps.
Its sulfur content should be low. Various amounts of carbon black from 191 to 391 by weight of diamond are acceptable, but about 2- by weight has been found to be optimal.

The paraffin utilized in the first (or peripheral) dispersion may be any of the hydrocarbon waxes referred to by the term. Again, high purity hydrocarbons should be used to prevent harmful residues. For each mixture liquid paraffin is used. However, from the table it appears that this is achieved by operating at temperatures high enough to melt the paraffin, which is normally solid under ambient conditions. The amount of paraffin used is not significant, as it is later removed. In general it weighs 3- of the total weight of the first dispersion.
There are 6 rumors.

The combined components are simply mixed together to form the first dispersion. However, from moths, a very dense and homogeneous dispersion is preferred. Therefore, a step-by-step technique as outlined in the flowchart of FIG. 1 is desirable.

According to this technique, in order to provide a uniform coating on the crystal surface,
Contains diamond crystals and carbon plastic. Only after this stage is paraffin mixed into the formulation.

Thereafter, the first dispersion is preferably crushed by a grinder or the like.
It is then subjected to a further refinement stage. However, a secondary product containing carbon fiber, carbon black and paraffin
The mixing of the dispersions is passed through a screen of, for example, about 20 meshes, thus improving mixing and reducing any aggregates that may have formed.

The paraffin and carbon brane used in the second dispersion (or core) of the method may be any of those described above. For convenience, a similar number of four is usually used to form both the first and second dispersions. Generally, the second dispersion also contains, by weight, from 3 to 6 inches of paraffin and from 2 to 4 inches of carbon dioxide. Particularly in the first dispersion, the amount of carbon plastic and the quality and type of carbon plastic are important. For example, sulfur contaminants in carbon black must be avoided.

The carbon fibers used are preferably of very small size in order to facilitate homogeneous mixing and, in particular, refining operations. The fiber size is preferably 6 to 30 microns in diameter and 250 to 500 ζ microns in length.

Fillers are provided to increase the volume and also improve the compressibility of the fiber-containing powder mixture. For many applications it is highly desirable.

Such filler may be any material that is stable under the conditions to which it is subjected during sintering and use, but finely divided silicon carbide is preferred. Typically, 40 to 75 fillers based on the total weight of the second dispersion are used.

As with the original dispersion, the paraffin, carbon fiber, carbon fiber and filler must be uniformly mixed. It is preferably screened to ensure fineness as described above.

The presence of paraffin allows each dispersion to be separately compression molded (or shaped) into the desired shape. Application of pressure results in a compression molded dispersion having sufficient compaction strength or physical stability to retain its given shape during subsequent processing or handling. The applied pressure may vary widely, but should be at least 2300 K.
g/cs” is preferred.

In the method of the invention, one of the two dispersions is compression molded to correspond to the final part of the composite.

This compression-molded dispersion therefore contains parts of the final composite, such as the core, the shape and volume of the cutting edge (
Forms an intermediate compression molded body similar to the structure (not texture).

After an intermediate compression molding is formed from one dispersion, it is recompression molded with the remaining dispersion. For this step, if desired, the intermediate compact is placed in a mold having the shape of the desired composite. The remaining dispersion is then added to the mold to complete the filling. One dispersion must be compression molded at each of the above steps, but the order is not critical. Applying pressure as described above also yields a physically stable duplex compression molded body having the same shape as the final bonded composite.

What is important in these operations is the shape of the mold. An important advantage of the present invention is that the round shapes added to the compression molded body during molding typically do not need to be subsequently removed. Thus, the time consuming and difficult steps of polishing and finishing to the desired shape, common with other refractory materials, are eliminated by the present method. The mold or plunger must have the shape required for the final body portion to which the compact or composite will correspond.

Figures 2 to 6 show the molding equipment and process sequence. The device consists of a base B, a molded iris forming a cavity C, and a plunger P1). Plunger PK is
It fits into the mold v and the cavity C to precisely define the final shape of the insert or compression molded body. In FIG. 5, the insert material (first dispersion) 1 is introduced into the cavity,
A Kuzuranja P2 is then used to close the cavity and compression mold the material 1 into the annular part 2 shown in FIG. In FIG. 5, the plunger P has a flat surface and the fractured insert 2 is filled with the remaining (second) dispersion 4. In FIG. Upon completion of the compression molding process shown in FIG. 6, the five compression molded bodies are removed for sintering. Once molded to the desired shape, the two-layer compact (as shown in FIG. 1) is subjected to vacuum and temperature conditions sufficient to evaporate the paraffin from the entire volume. Of course, the appropriate conditions are
The temperature present there is used. As an alternative, different temperatures and correspondingly different vacuums are used.

Evaporation of the paraffin is preferably carried out under slow pressure. This prevents the gas pressure from building up, for example in the event of violent boiling within the complex. Accordingly, conditions requiring at least 410 minutes, and preferably 10 to 15 minutes to substantially completely remove paraffin, are preferred.

The compact is then infiltrated with liquid silicone.

Sufficient silicon element must be present for the silicon to penetrate into the carbon fibers and to cause a reaction between the carbon black and the carbon fibers and the silicon. Excess silicon may be present.

Even if a small amount of free silicon remains in the finished composite after sintering, it is not harmful.

An excess of silicon of up to about 14 to 12 hours is desirable to ensure a substantially complete reaction.

The process of joining compression molded bodies to form a composite is
It actually involves a series of steps, which are performed substantially simultaneously. These steps are melting of the silicone, infiltration of the molten silicone into the compact, and reaction of the rolled, infiltrated silicone with carbon bras, glue, and carbon fibers to create β-silicon carbide in the finished composite. .

To induce this last series of reactions between silicon and silicon, a minimum temperature of at least 4°C is required. y) can take advantage of high temperatures. However, in order to prevent diamond crystals from becoming graphitized,
The maximum temperature is preferably 1490°C. Usually, the pressed compact is 14
at 90° C. for at least 10 minutes, and preferably at 145° C.
It should be maintained at 0-1490°C for at least 50 minutes. This ensures that the carbon plastic and carbon fibers present react substantially completely with the infiltrated silicon. Accordingly, the entire operation may proceed step by step, substantially simultaneously in a sequence, or sequentially, as desired.

The method of the present invention does not require the application of pressure during silicon infiltration or sintering. This, of course, means that there is no need for a hot breath mold at this stage of the method. Other methods, such as U.S. Pat. No. 4.124.
Methods such as those described in No. 401 rely on pressures of 2αOOOOpsi or more for this part of the method.

Once the reaction of the carbon bra, resin, and carbon fibers with the silicon is substantially complete, the bonded product composite is cooled. Once the composite is formed into the desired shape, it is ready for use. Therefore, it usually has cutting tools,
It is shaped into a wire drawing die or other conventional article as required for its properties.

These bonded round-neck bodies generally have layers that indicate their production process. Primarily, the layer is represented by a filler of the second dispersion (core) and diamond crystals on its surface. These nine different layers are bonded together by a bonding matrix of β-cricon carbide. Thus, for example, if the filler of the second dispersion is β-silicon carbide, as is desirable, then the layer is substantially composed of 1ca- and β-silicon carbide. Generally, about 5 to 14 silicon and about 02 to 02 carbon may remain as unreacted components per weight. Silicone residue may be present throughout the composite.

However, the residual carbon derived from the first dispersion must be less than or equal to nose by weight.

The peripheral side surface portion 2#i of FIG. 5 derived from the first dispersion usually consists of mostly diamond crystals and a small amount of β-silicon carbide. A major feature of this layer is the presence of diamond crystals, which preferably range from about 75 to 90 by weight.

The composite of the present invention is improved by nitriding.

In this process, a nitrogen insertion step is shown in which nitrogen flows into the vacuum furnace to convert the remaining silicon elements to silicon nitride. In one example of this step, nitrogen is flowed into the furnace at a higher temperature of about 1 fOO1 for less than one hour to form amorphous Si3 [4 and perform surface nitridation. Prior to this step, the furnace atmosphere is flushed with hydrogen, nitrogen, or both to reduce the atmosphere. A self-closing process prevents additional nitrogen from penetrating deep into the insert, providing only a surface treatment.

The present invention requires only the introduction of elementary gas into the furnace and is therefore simple, inexpensive, easily automated, and virtually non-contaminating.

Furthermore, without using high temperature and high pressure technology as in the past,
Thus, the conventional 81914 is also amorphous 81314.
Create. The hardness of amorphous 813 [4 is 81,
Although the hardness of A4 is also low, it is
When cutting materials such as alloys, there is no need to cut the material onto the insert.
81 alloy build-up, increases the density of the surface of the insert, enhances hardening of the binder phase, increases the bending strength of the insert by 20 to 40 degrees, and increases wear resistance.

The composite formed according to the present application can have any shape of cutting inserts known in the art. Generally, these inserts have indexable features. That is, during use, they are rotated about their central axis;
The cutting edges around them are parallel to the central axis, but intersect with each other. Certain preferred embodiments of the present invention include moss dryers in these shapes. For example, the insert 5 of FIG. 6 has 92 substantially parallel planar surfaces spaced a predetermined distance apart. These surfaces represent the anterior and posterior surfaces of the insert, their separation distance, the depth of which is typically α1 to α2tym.

The periphery of the insert 50 has upper and lower surfaces (each side of which is preferably substantially rectangular in appearance). The sides of the neutral cutting insert are parallel to an axis perpendicular to the planar surface. However, as shown in composite 5, the sides of the positive cutting insert have clearance angles. Each separate side is therefore trapezoidal.

The insert 5 in FIG. 6 clearly shows the hard crystals concentrated in a ring shape (rim part) 2 and the central part 4 where most of the hardening crystals are dangerous. The cross section of the ring structure 2 is preferably triangular. The ring structure 2 also has an upper hard crystal disk surface, which has the surface shown in FIG.
A layer (6) of cemented carbide crystal covers the entire upper surface of the insert 5 with a slight spacing as well. In forming this upper surface 6, a polygonal structure 7 shown in FIG.
It forms irregular triangular cutting edge structures (clumps) 8, and these are the central parts! y) can be made higher to obtain a two-stage effect. By this method, most of the hard crystals are
In the cutting edge structure, we are concentrating on dosages that increase strength. The cutting structure 8 also projects laterally and forwardly from the insert, as shown in Figures 7 and 6;
In FIG. 8, for example, the insert 10 has a hard crystal cutting structure 11 having surfaces 12.15 and 14.
and projecting laterally, forwardly and upwardly as shown. Furthermore, the actual relationship of the cutting edge structure of the polygonal insert to the workpiece is not symmetrical, i.e., one side of the cutting edge hits the workpiece more than the other side, so the cutting edge Structures can also be formed complementary.

The polygonal insert 15 of FIG. 9 shows an asymmetric, generally triangular, hard crystal cutting edge structure 16 with long sides for application to a workpiece.

Rectangular structures can also be used in much the same way.

These protrusions minimize subsequent polishing operations. A recess 24 is preformed.

As mentioned above, the method of the present invention can be employed to confine, disperse, or concentrate the crystalline structure of the present invention to predetermined areas.

The highly concentrated cutting edge crystal structure effectively becomes an insert in the inner matrix. A supporting crystal layer is used as shown in the cross-section of insert 17 in Figure 10 to provide a better bond between the cutting edge structure and the base material, to keep the amount of hard crystals to a minimum and to increase the overall toughness of the insert. can do. As shown, the cutting edge structure 18 is separated from the base material 19 by a lower layer of hard crystals 20, the hard crystal layer 20 having a lower concentration of hard crystals than the concentration of hard crystals in the cutting edge structure 18. This layer 20 creates a stress gradient in the insert and may be layered as shown or
Continuously varying concentrations can be provided separately from or as part of the cutting edge structure 18. In addition, as shown in FIG. 10, the cutting edge structure 18 is formed to have a rake angle on the side portion 21 in order to minimize the subsequent grinding work. Different forces are required to compression mold the blade structure 18 and the base material portion 19. These pressures can be equalized by making the press anvil convex in cross section. The insert is thus compressed to a thinner cross-section in the central and more compressible portion 22 of the insert when the crystal cutting edge structure exerts maximum compressive force. This thin cross-section provides a rim-like lower surface 23 that aids in tightening the insert into the bite holder.

The method of the present invention provides an advantageous retention arrangement in a tool holder by forming the two-stage region, rim structure, and recess. For brazing processes, an easily brazed material such as cobalt or its compounds is dosed as a base layer for the insert, and when the insert is sintered, the metal base layer of the brazing round become.

For mechanical gating devices, the recess 24 of FIG. 9 includes a plate or washer 25 of a comparative material, such as copper, bonded to the inner 15. plate 2
The upper surface of 5 is higher than the upper surface of the hard crystal cutting edge structure 16 and serves to receive the tightening force against the inner. If the insert is like insert 26 in Fig. 11,
When made with a very thin cross-section, by using an annular protrusion 27 with upright two-pulls 28,
Can be installed with insert protected. Opening 2 in insert 26? is provided and positioned in a precise fit over the nipple 28. At the same time, a hard metal washer 37 is placed on the insert 26 and the front edge of the pull 28, and a pin member such as a screw is inserted into the front edge of the pull. Tighten it to the tool holder.

In this way, excess stress is borne by the nipple and prosthesis rather than the insert.

If the stress is excessive, the structure of FIG. 12 is used. In FIG. 12, the insert 30 is, for example, as shown in FIGS. 8 and 9, and includes a hard metal shock absorber blower 51. This block is also smaller than the insert and its periphery rests on all cutting edge structures. The clamping force of this professional mounting plate distributes stress to all inserts.

Rounding of the layer concept based on this method, various other shapes can be made, for example, a cutting die is dispensed on either surface, a round annular insert, and a drawing die with an internal cutting edge.

Regarding the tightening and general dimensional stability of the insert, the insert illustrated in FIG. 13 is used. 13th
In the figure, the insert 32 includes a pre-compressed central matrix 33 to provide structural and dimensional stability. Thereafter, the layer or enclosure of carbide crystals is
It is only compression molding of crystalline materials. The composite is then sintered in a conventional manner. Metal layer 35 serves to bond the insert into the base.

[Brief explanation of the drawing]

FIG. 1 is a 70-chart of the method of the invention; FIGS. 2-6 are sequential illustrations of the preferred method of the invention and specific equipment advantageously used in the method; FIG. 7 is a geometric Figure 8 shows a composite insert having a carbide crystal arrangement with mechanically raised corners; Figure 8 shows a composite insert with carbide corners galvanized in multiple directions from the composite; Figure 9 The figures show a composite with a recessed upper surface for holding the clamping plate: Figure 10 shows a circular composite with a triangular cross-section cutting edge with a gradient layer; Figure 11 shows a composite with a mating A clamp washer is shown; FIG. 12 shows a stress dispersion device in a composite clamping device; and FIG. 13 shows a thin composite with an enclosed structure of cemented carbide crystals. DESCRIPTION OF SYMBOLS 1... Insert material, 2... Circular part, 3... Pro, Kuplunga, 4... Compression molded body of remainder, 5...
・Insert, 6... Upper surface, 7... Polygonal structure, 8... Cutting edge structure,! ... Central portion, 10... Insert, 11... Cutting blade structure, 12. 15 e14・
...Surface, 15...Polygonal insert, 14...Hard crystal cutting edge structure, 17...Insert, 18...
Cutting blade structure, 19... Base material, 20... Hard crystal layer,
21... Side part, 22... Compressible part, 25...
・Plate, 27... Circular block, 2B・φ・2,
Full, 33... Base material, B... Heath C... Cavity,
P...Plunger, M...Pamault 0゜Patent applicant General Electric Company representative me (763
0) Kakuji Ikunuma Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 11 Figure 12 Figure 9 Figure 13

Claims (9)

[Claims] (1) A method for making a combined nine-composite cutting element, comprising the following steps: (a) Forming a first dispersion of carbide crystals and carbon plastic in the halafin; (b) Forming a second dispersion of carbon fibers, carbon plastic, glue and filler in the halafin. (C) One of the dispersions is compression-molded to produce a physically stable intermediate compression-molded body; ((1) Rolling to create two series of compression-molded bodies; recompression molding with a dispersion of residue;
(a) placing the double compression molded bodies in a vacuum for a period of time at a temperature sufficient to evaporate substantially all of the carcass paraffin; (f) placing the liquid silicone in the double compression molded bodies; (g) Sintering the two compression compacts containing the infiltrated silicon under conditions sufficient to create a β-silicon carbide binder that binds the mosquito complex. ; and Ch) subjecting the two compression molded bodies to a nitriding treatment to convert the silicon element into silicon nitride. (2) The method according to claim 1, wherein nitrogen is introduced in the form of gas during sintering. (3) An insert comprising a layer of K carbide crystals on both upper surfaces, in which the carbide crystals are concentrated and a 9-majority O lump protrudes from the layer. (4) The insert according to claim 3, wherein the cemented carbide crystals are concentrated in a circumferential rim portion in the central portion, and the thickness of the rim portion is thinner than the thickness of the insert. (5) The insert according to claim 3, wherein the carbide crystals are concentrated in several cutting edge structures. 6. The insert of claim 3, wherein the cutting edge structure comprises a lower layer in which the crystals are relatively dispersed. (7) The insert according to claim 5, wherein the cutting edge structure protrudes from the insert. (8) The insert according to claim 5, wherein the cutting edge structure protrudes laterally, forwardly and upwardly from the base material. (9) The insert according to claim 5, wherein the shell insert has a recess formed in advance on the top surface or the bottom surface or both.