JPS6333985B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to machine tools such as cutting tools, milling tools and shaping tools, and more particularly to machine tool components comprising compacts of abrasive particles such as diamond or cubic boron nitride. Wentorf et al., U.S. Pat. No. 3,745,623 and
It has been found that diamond compacts made according to the teachings of No. 3,609,818 are of limited use because they thermally degrade at temperatures above approximately 700°C. Similarly, cubic boron nitride (CBN) compacts made according to the teachings of U.S. Pat. Nos. 3,767,371 and 3,743,489 have been found to have limited use. This compressed material also deteriorates thermally at temperatures exceeding approximately 700°C. For this purpose, it is common practice to (1) bond the compact to a support by means of a brazing material with a melting point near or above the thermal degradation point of the compact, or (2) to Such compacts cannot be used in applications that require forming the compact in a high melting point, abrasion resistant matrix such as those used in the present invention. According to the invention, a tool part comprises: (a) self-bonded particles selected from the group consisting of diamond and cubic boron nitride and comprising about 70-95% by volume of said part; (b) said particles and said part; about 0.05 to 3% by volume of a metallic phase consisting of a sintering aid material to selected abrasive particles of about 5 to 30% by volume of said part interconnected in a network partitioned by and distributed throughout said part; Hollow holes occupying % by volume. The present invention provides a machine tool section constructed with a compact consisting essentially of self-bonded abrasive particles and a network of interconnected pores distributed throughout. will be done. The compact is produced by bonding agglomerates of abrasive particles into a self-assembly using a sintering aid material under high pressure and high temperature (HP/HT). HP/
Bonds formed with HT include self-bonded particles with a sintering aid material (eg, cobalt or cobalt alloy) permeated throughout the bond. The penetrant is then removed, for example by immersing the conjugate in an aqua regia bath. It has been found that removing substantially all of this penetrant provides an abrasive particle compact with substantially improved resistance to thermal degradation at elevated temperatures. In another embodiment, a composite compact made in a manner similar to the first embodiment includes a layer of self-bonded abrasive particles and a substrate layer (preferably made of sintered carbide) bonded to the layer of abrasive particles. ) consists essentially of Although FIG. 1 actually depicts a diamond compact, it is equally illustrative of another embodiment of the invention in which the abrasive particles are cubic boron nitride (CBN). The diamond particles 11 constituting the compressed material account for 70 to 95% by weight of the compressed material. Particles are used herein to mean individual microcrystals or fragments thereof. Interface 13 indicates self-bonding or diamond-diamond bonding of adjacent particles 11.
The same diamond crystals 11 found on the ground surface of the compact shown in the figure are bonded to adjacent diamond crystals (not visible in the figure) in the third dimension. It is believed that the metallic phase of the sintering aid material (not shown) penetrates substantially uniformly throughout the compact and is encapsulated within the closed region formed by the adjacent diamond grains. . This phase accounts for about 0.05-3% by volume of the compact. A network of interconnected empty pores 15 are distributed throughout the compact and are bounded by diamond particles 11 and a metallic phase (not shown). The holes 15 constitute approximately 5-30% by volume of the part. In one embodiment, the compact consists entirely of self-associating particles. In another embodiment, the compact is bonded to a substrate (not shown), preferably comprised of cobalt sintered tungsten carbide. An acceptable particle size range for diamond particles 11 is 1-1000 micrometers. Acceptable grain sizes for CBN range from 1 to 300
It is a micrometer. Briefly, a preferred embodiment of a method for preparing a tool component in accordance with the features of the present invention comprises the following steps. (a) placing in a reaction cell or charge assembly a mass of abrasive particles selected from the group consisting of diamond and CBN and a mass of a material active as a sintering aid for the selected abrasive particles; b) simultaneously subjecting the cell and its contents to a temperature in the range 1200-2000°C and a pressure in excess of 40 kilobar; (c) stopping the heat input to the cell; (d) removing the pressure applied to the cell; (e) formed in steps (a) to (d),
An abrasive composite consisting of particles in a self-bonded form and a metallic phase consisting of a sintering aid material permeated throughout the abrasive composite is removed from the cell, and
(f) removing substantially all of the metallic phase that permeates the entire composite so that the phase accounts for about 0.05 to about 3% by volume of the part; "Simultaneous" in step (b) above means HP/
It means that the HT conditions exist or occur at the same time, but it does not mean that the start or end times of the HP and HT conditions coincide (although they probably do). In this case, we will refer to a catalyst for diamond as shown below and/or a substance that promotes sintering of CBN as shown below. Preferred embodiments of steps (a) to (e) in the above method for manufacturing diamond particle tool parts are described in more detail in US Pat. Nos. 3,745,623 and 3,609,818. Briefly, as described in these patents, a diamond compact is prepared by a HP/HT process in which hot compacted diamond particles are subjected to axial or radial incorporation of catalyst material into the diamond particles. is penetrated by the catalytic material by a general dispersion in the direction. Catalytic sintering throughout the diamond particles occurs resulting in extensive diamond-diamond bonding. As described in U.S. Pat.
A catalytic metal in the elemental form selected from Ta, (2) a mixture of alloyable metals of catalytic and non-catalytic metals, (3)
It is selected from alloys of at least two of the catalytic metals, and (4) alloys of catalytic metals and non-catalytic metals. Cobalt in elemental or alloyed form is preferred. This material forms a metallic phase within the HP/HT formed abrasive combination as shown in step (e) above. Preferred embodiments of steps (a) to (e) of the above method for manufacturing tool parts of CBN particles are disclosed in U.S. Pat.
It is described in detail in No. 3767371. As described in connection with Example 1 of that patent:
CBN compressed material was prepared by HP/HT method,
CBN particles are melted sintering aid material (cobalt metal)
is infiltrated with this auxiliary material by being dispersed axially throughout the CBN particles. During global infiltration, sintering of the CBN particles occurs resulting in extensive CBN-CBN bonding. Other materials that can serve as sintering aids for CBN are disclosed in U.S. Pat. It is an alloy with an alloying metal. Cobalt and cobalt alloys are preferred. The sintering aid material forms the metallic phase shown in step (e) above. U.S. Patent No. 3745623, U.S. Patent No. 3767371 and U.S. Patent No.
One embodiment of steps (a) to (e) according to No.
CBN) is bonded in-situ to a sintered carbide substrate to produce a composite compact. Materials for forming the carbide substrate (derived from either carbide molding powders or preforms) are the preferred source of sintering aid materials. For exemplary details of the substrate, see U.S. Pat. No. 3,745,623, column 5, line 58 to column 6, 8.
row, as well as column 8, line 57 to column 9, line 9. Another embodiment of the invention involves forming a compact consisting essentially of self-bonded abrasive particles. In this embodiment, steps (a) to (e) are also repeated as described above, except that it is preferred to omit the provision of a carbide compacted powder or preformed material to form a carbide support for the abrasive particle layer. It was carried out in the same manner as above. When this is done, the sintering aid material is added separately as shown in US Pat. No. 3,609,818. Of course, after removal of the metallic phase (step f), a support of cemented carbide or other material may be brazed to the compact to form a tool blank or insert. In accordance with a feature of the invention, the metallic phase is removed from the compact by acid treatment, liquid zinc extraction, electrolytic depletion or similar methods, resulting in a compact that has nearly 100% of the abrasive particles bound in a self-bonded form. leave. Thus, the compact is substantially free of residual metal phases to catalyze the reverse conversion of abrasive particle bonds and/or to expand and break particle bonds. It is theorized that these two mechanisms are responsible for the thermal deterioration of prior art compacts at high temperatures. The compressed material produced by the present invention can be heated up to 1200°C without substantial thermal deterioration.
Can withstand exposure to temperatures up to ~1300℃. Example 1 (1) In the 0.05mm zirconium container assembly, the nominal 8
of fine diamond particles less than micrometers
1.4 mm layer and sintered tungsten carbide (Co; 13 wt.%, WC; 87 wt.%) with a thickness of 3.2 mm and a diameter of 8.8 mm, (2) as shown in Figure 1 of U.S. Pat. No. 3,745,623.
Stack many of these aggregates in the HP/HT device and (3) increase the pressure to about 65 kbar and the temperature to about 1400 kbar.
℃ and maintained for 15 minutes, (4) slowly lowering the temperature first and then the pressure, (5) removing the sample from the HP/HT apparatus and grinding it into a 2.7 mm thick cobalt sintered tungsten carbide layer. A compressed product made by bonding diamonds with a thickness of 0.5 mm was obtained, and a plurality of disk-shaped diamond compressed products were prepared. The carbide layer of each compact was removed by surface grinding. As shown in Table 1, half of the samples were leached in a hot concentrated acid solution to remove the metallic phase and any other soluble non-diamond material. Two methods were used to remove the penetrant. Samples A-1 to A-4
For the first group named
sample A-3 and A- using concentrated nitric acid-hydrofluoric acid.
4 was processed. For the second group, designated Samples B-1 to B-4, samples B- 3 and B-4 were treated. It was found that using the latter acid solution significantly increased the removal rate. Samples A-3 and A-4 were acid treated for 8 to 12 days.
Samples B-3 and B-4 were treated for 3 to 6 days.
During the acid treatment for either method, the dimensions of the sample did not change and no diamond fractures were observed. Therefore, any weight loss is based on the removal of the metal phase penetrant, since diamond is not dissolved in acid. The amount of metal phase penetrant in such a compact is
Calculations based on density measurements of the compact prior to leaching were approximately 8.1% by volume or 19.8% by weight of diamond and metal starting materials to produce the compact. After leaching, approximately 0.5% by volume or 0.2% by weight of penetrant remains. The removal of up to 90% by weight of penetrant (Sample B-4) also shows that most of the locations of the metallic phase are within the continuous network of pores. Scanning electron microscopy (SEM) of the fractured surface of the leached sample
Inspection showed a network of pores running throughout the diamond layer. The pores are distributed throughout the layer, most with a diameter of 1
It was less than a micron in size. This served to allow the acid to penetrate the entire diamond layer and remove the metallic phase almost uniformly throughout. As shown in Table 1, transverse fracture strength (TRS) and Young's modulus were also measured for the diamond layer. Strength tests were performed on a three-point beam loading device. This device consists of two steel rollers placed on a support with a third steel roller placed above in the center, with the axis of the third roller parallel to the other two rollers. . The sample was loaded onto the lower two rollers until a centered break occurred. Strain in the sample was measured in a direction parallel to the tensile stress using a resistive strain gauge coupled to a resistive strain indicator.
Samples A-1 through A-4 were prepared for strength testing and surfaced with a diamond wheel (177-250 micrometer diamond particles). Samples B-1 to B-
Samples A-4 were prepared for strength testing by being surface-finished with a lapping machine using a 15 micrometer diamond abrasive to obtain a more scratch-free surface than that obtained for samples A-1 to A-4 by grinding. A well-polished surface in a specimen finished with fine diamonds gives higher strength values because a more complete surface condition is obtained, ie, there are fewer stress-concentrating defects.
This indicates that the leached samples (A-3, A-4, B-
3, which is believed to explain the lower TRS values measured for B-4).

[Table] In contrast to TRS test results, E measurement values (Table 1)
is not affected by porosity. This is E
This is because it is a measure of the internal strength and stiffness of the material, not the formation of microscopic cracks. Even if the metal phase penetrant is removed from the sample, the average change in E is only about 12%.
It only got lower. E=M・C/I (where E=Young's modulus M=moment C=distance to outer fiber I=moment of inertia of area) and M・C do not change, but the effective area is proportional to the porosity. This difference should be corrected for porosity in leached samples, since I becomes smaller due to the decrease. Therefore, the spherical void and random distribution are E=
Assuming M.C/I(1-x), where x is a fractional value of porosity, the value of E will be larger than the measured value. Average value of E for samples B-3 and B-4 79×10 ³
Kg/mm ² (However, the leached amount is corrected to 85×10 ³ Kg/mm ² which is approximately 5% smaller than the average value of E for samples B-1 and B-2, 90×10 ³ Kg/mm ² ). The results show that the effect of removal of the metal phase penetrant on E is extremely small, indicating that the strength of the diamond layer is almost completely due to the diamond-diamond bond. The E value of 90×10 ³ Kg/mm ² is about 10% lower than the average value of 100×10 ³ Kg/mm ² calculated from the single crystal diamond elastic modulus. Example 2 Instead of 8 micrometer diamond particles
105 with 149-177 micrometer diamond particles
~125 micrometer diamond particles 1:1
The compacts were prepared in the same manner as given in Example 1 for samples A-1 to A-4, except that the mixtures were used. The calculated value of the compact before leaching is Diamond 89.1
weight% (96.5% by volume) and metallic phase 11.9% by weight
(4.5% by volume). After leaching, 11.5% of the total weight of the compact is reduced, i.e. about 0.15% by weight of metallic phase.
(0.06% by volume) remained in the compact. Example 3 Four diamond compacts were made as disclosed in Example 1. Carbide was removed by grinding from each compressed product. Two of them are heat 1HF:1HNO ₃ and
The metal phase penetrant was removed by leaching in 3HCl: _1HNO3 acid. All this then using epoxy
Mounted on a 0.89 cm circular tungsten carbide substrate. Attach this complex to the tool holder in the lathe,
A wear resistance rotation test was conducted. Processed products are trademark names
They were rubber logs filled with silica sand, commercially available as Ebonite Black Diamond. Test conditions: surface speed 107-168 surface m/min (maximum range is 24 surface m/min for one heat treatment group), cutting depth 0.76 mm, lateral feed 0.13 mm/rotation, test time 60 minutes.
After testing, the samples were heat treated in a tube furnace in a flowing atmosphere of dry argon. Processing temperature is 700℃~1300℃
Exposure was performed at 100°C intervals. Exposure time was 10 minutes at each temperature. After each treatment, the samples were examined under a scanning electron microscope (SEM) for signs of deterioration, and then the samples were mounted for wear testing, except for the 1000°C, 1100°C, and 1300°C treatments. Both the top and bottom edges were used as cutting edges before regrinding. Abrasion test results are listed in Table 2. The samples were fairly uniform throughout the test. A tendency for wear resistance to decrease from untreated to first heat treatment at 700°C was observed. The unleached samples, Samples 3 and 4, remained unchanged until catastrophic thermal failure at 800°C to 900°C. Heat treatment had no effect on wear resistance until the diamond phase no longer captured and contained the metal phase and cracking occurred.
This behavior also indicates the presence of two distinct phases. That is, the bonded diamond phase that undergoes cutting in the test, and the metal phase that is left over from the sintering process. The leached samples, Samples 1 and 2, withstood heat treatments up to 1200°C very well. At 1200 °C, there is a slight tendency for sample deterioration, indicating the onset of thermal inversion at the surface.

[Table] The test results in Table 2 show the time per inch of compressed material wear x 100. Tool wear was measured by measuring the width of the "flat" formed on the compacted material upon contact with the workpiece. This data is only meaningful for comparing the relative performance of leached and unleached samples. Leached samples have on average higher test values than unleached samples. This may be the result of thermal degradation of the unleached compact during machining of the sample cutting tests. Therefore, the same deterioration mechanism actually occurs during the wear test as during heat treatment. If so, when the tool tip is heated to high temperatures while in contact with the workpiece, the cobalt phase expands more than the diamond phase and cracks the tip edge within the first few grain layers. I get tired. As a result, the damaged tip becomes weak and exhibits poor performance. However, the leached sample is thermally stable up to higher operating temperatures and is not thermally damaged upon contact with the workpiece. SEM analysis revealed that the unleached sample exhibited many different properties compared to the leached sample. When viewed at 2000x magnification, the metallic phase began to protrude from the surface at 700°C to 800°C. When the temperature increased to 900 °C, the sample cracked radially from the rotating blade toward the center of the sample. The leached sample did not show this behavior and remained relatively unchanged up to 1300°C. At 1200°C, the diamond layer is clean and unaltered; at 1300°C, the 20x photo looks rounded and fuzzy, and the 1000x photo shows that many crystals are exposed and the surface is corroded. This is probably due to thermal deterioration of the surface and may also be the result of small amounts of oxygen impurities in the argon atmosphere of the tube furnace. Example 4 Two diamond compacts (Samples 4-1 and 4-2) were made as described in Example 1, except that the carbide substrate was not cut away. Epoxy plastic (Epon 826 resin, Nozick methyl anhydride and benzyldimethylamine hardener) was cast around Sample 4-1 and cured. All plastic on the surface of the layer was sanded away to expose the surface of the diamond layer. Next, sample 4-
1 in boiling 3HCl: _1HNO3 for 37.15 hours. After removal from the acid, the plastic was visibly removed from the char layer. There were some signs of reaction between the acid and the unexposed surface. However, the surface of the carbide layer did not appear to be significantly damaged by the acid. Next, the surface of the diamond layer was examined using SEM (magnification up to 2000x). The surface of the diamond layer had a similar appearance to the surface of the diamond layer of the leached sample of Example 1. Sample 4-1 was then examined by energy dissipative X-ray analysis to compare the concentrations of the components of the metallic phase to the same type of unleached compact. SEM and X-ray analysis results showed that the acid served to penetrate the diamond layer and remove a substantial portion of the metallic phase. Samples 4-1 and 4-2 were then subjected to a wear resistance rotation test conducted in the same manner as disclosed in Example 3 above. The abrasion test results (calculated as in Example 3) were as follows for sample 4-1 (leaching):
120−150 and for sample 4-2 (unleached)
It was 100-120. These test results showing the superiority of the leached compacts are consistent with the results obtained in Example 3, and thus the removal of the metallic phase in the region of the blades improves the performance of the diamond compacts. It has been demonstrated that

[Brief explanation of the drawing]

The figure is a photomicrograph of a portion of the polished surface of a diamond compact made in accordance with features of the present invention.

Claims (1)

Claims: 1. (a) self-bonded particles selected from the group consisting of diamond and cubic boron nitride and accounting for about 70-95% by volume of the part; and (b) an abrasive particle aggregate selected from above. The metallic phase consisting of sintering aid material for about 0.05 to 3
% by volume and a network of interconnected empty holes delimited by said particles and distributed throughout the part and occupying about 5-30% by volume of the part. 2 The particles are diamond, and the metal phase is (a)
an elemental catalytic metal selected from group metals Cr, Mn, and Ta; (b) a mixture of catalytic and non-catalytic metals capable of forming an alloy; (c) an alloy of at least two of the catalytic metals; d) The tool component according to claim 1, which is selected from the group consisting of alloys of catalytic metals and non-catalytic metals. 3 The size of the diamond particles is about 1 to 1000
Claim 1 which is in the range of micrometer
The tool component described in item 2 or item 2. 4. the particles are cubic boron nitride, the metal phase is substantially uniformly infiltrated throughout the part, and the metal phase is composed of cobalt, cobalt alloys, and aluminum with Ni, Mn, Fe, V, and Cr. A tool component according to claim 1 selected from the group consisting of alloys with selected alloying metals. 5. Claim 1 or 4, wherein the CBN particles have a size in the range of 1 to 300 micrometers.
Tool components listed in section. 6 The transverse breaking strength of the part is at least approximately 35 kg/mm ²
A tool component according to any one of claims 1 to 5. 7 The Young's modulus of the part is at least approximately 50,000 Kg/mm ²
A tool component according to any one of claims 1 to 6. 8. Claims 1 to 7 in which the component further includes a sintered carbide substrate bonded to the self-bond.
A tool component described in any of paragraphs. 9 (a) placing in a reaction cell an aggregate of abrasive particles selected from the group consisting of diamond and cubic boron nitride and an aggregate of a sintering aid material for the abrasive particle aggregate; cell and its contents from 1200 to
simultaneously applying a temperature in the range of 2000°C and a pressure in excess of 40 kbar; (c) stopping the heat input to said cell; and (d) forming a self-bonded bond formed by steps (a) to (c). (e) removing substantially all of the material that has permeated into the combination and removing the material from the part; A method of manufacturing a tool component in which the tool component occupies about 0.05 to about 3% by volume of the tool. 10 The particles are diamonds, and the substance is (a)
a catalytic metal in an elemental form selected from the group consisting of group metals Cr, Mn, and Ta; (b) a mixture of catalytic and non-catalytic metals capable of forming an alloy; and (c) at least two of the catalytic metals. alloy, (d) alloy of catalytic metal and
(e) The method according to claim 9, wherein the metal is selected from the group consisting of non-catalytic metals. 11 The particles are cubic boron nitride and the substance is
10. The method of claim 9, wherein the method is selected from the group consisting of Co, alloys of Co, and alloys of Al with alloying metals selected from Ni, Mn, Fe, V and Cr. 12. A method according to any of claims 9 to 11, wherein the metal is removed from the conjugate by immersing the conjugate in an acid. 13. The method according to claim 12, wherein the acid is aqua regia, nitric acid, hydrochloric acid or hydrofluoric acid. 14. A method according to any of claims 9 to 11, wherein the metal is removed from the composite by liquid zinc extraction. 15. The method according to any one of claims 9 to 11, wherein the metal is removed by an electrolytic depletion method.