JP2003147410A - Abrasive, sintered-compact block and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a diamond sintered compact block with high precision and in a high yield, used for anvils for research under an ultrahigh pressure, forming dies for hard materials and component materials of cutting tools such as a glass-fiber cutter and a scriber. SOLUTION: This method comprises; (1) preparing a forming die 11, 12 composed of a heat-resisting material and having, in its inside, a cavity of a solid form in which, between the maximum length (axial length) in a pressing direction and the maximum size (cross-sectional length) perpendicular to the pressing direction, the smaller dimension is >=10 mm and the larger dimension is >=20 mm; (2) constituting starting materials in the form of a powder mixture 17 containing super-abrasive powder and binder raw-material powder; (3) charging the starting materials into the above forming die, closing the opening of the die, and arranging heaters for electric heating around the die; (4) charging the whole into a uniaxial press and adjusting the central axis of the forming die to the pressing direction; (5) subjecting the starting materials to pressure/temperature conditions within a region where the super abrasives are thermodynamically stable to integrally sinter the starting materials; and (6) carrying out cooling and pressure release and then recovering the resultant sintered-compact block.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superabrasive grain sintered body block, particularly various wear-resistant parts, an anvil for ultrahigh pressure research,
The present invention relates to a diamond sintered body having a three-dimensional shape suitable as a material for a grinding / polishing tool, and an effective manufacturing method thereof.

[0002]

Description of the Prior Art Various high hardness to wear resistant members
It is composed of superabrasive grains, especially a sintered body of diamond (PCD), and is used. These are generally obtained as follows. That is, diamond powder is mixed with a metallic or ceramic binder powder, and together with a cemented carbide plate as a support, it is placed in a high melting point metal capsule such as tantalum or zirconium, and diamond is thermodynamically stable. Under ultra high pressure and high temperature conditions. At this time, from the cemented carbide, a molten metal containing an iron group metal as a main component is supplied, which penetrates between the particles of the mixed powder and performs sintering in the diamond layer, and at the same time, the diamond layer and the support. Join. Such a method is known, for example, in Japanese Patent Publication No. 52-12126.

As a mold, die, or other wear-resistant component, it is desired to develop a three-dimensionally shaped diamond block suitable for a sintered body having a large cross-sectional area, particularly a component having a large-thickness and large cross-sectional area. From the viewpoint of the equipment, the success of upsizing of the ultra-high pressure equipment has recently made it possible to obtain a sintered body having a large cross section. However, according to the conventional method, it is possible to sinter with relatively small capacity parts without problems, but with large diameters, the shape tends to be distorted, and cracks tend to occur as the thickness increases, so perfect Hard to get. Therefore, those with a large thickness are limited to those with a relatively small diameter, and in the end, it is difficult to obtain a sintered body having both the axial length and the length of the cross section perpendicular to the axial length of more than about 10 mm in the prior art. It was

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention essentially eliminates the problems of shape distortion and cracks in a diamond sintered body having a large three-dimensional shape, which has not been achieved by the conventional method, and thus the ultrahigh pressure To provide a method capable of manufacturing a diamond sintered body block suitable for a tool blade constituent material such as a glass fiber cutter and a scriber with high precision and high yield, including an anvil for researching physical properties below, a mold for hard materials Is one of the main purposes.

The present inventors have examined various reaction chamber configurations when pressurizing with a press, and the shape configuration around the starting mixed powder to be pressurized / heated, and as a result, stress from the start of pressurization to depressurization The present invention has been achieved as a solution to the above-mentioned problems by finding an optimum configuration for eliminating discontinuity in distribution.

[0006]

Means for Solving the Problems In the present invention, the three-dimensionally shaped superabrasive grain sintering block can be obtained as follows. That is, (1) prepare a mold having an inner surface-shaped void portion that is made of a heat-resistant material and has a cross-sectional area that decreases from the opening portion toward the bottom portion.
Maximum length in the pressing direction (axial length) and maximum dimension perpendicular to the pressing direction
(Cross-section length), the smaller one has a solid shape of 10 mm or more, and the larger one has a solid shape of 20 mm or more, while (2)
The starting material is constituted as a uniform and dense mixed powder containing the superabrasive powder and the binder raw material powder, (3) the starting material is put into the above mold, and the opening is closed with a heat and pressure resistant block. , Again after arranging the heater for electric heating around
(4) The whole is loaded into a uniaxial pressure press, the center axis of the mold is aligned with the pressing direction, and (5) the starting material is pressure and temperature within the region where the superabrasive grains are thermodynamically stable. A sintered body block is obtained by subjecting to a condition to sinter and integrate, and (6) after cooling and releasing the pressure, the sintered body block is recovered.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION
Regarding the shape of the (cavity) to the sintered body block, a high yield can be obtained in an axially symmetric shape such as a sphere, an ellipsoidal sphere, a cylinder or a non-cornered cylinder, or a cone or a truncated cone, as shown in FIG. In the case of a sphere, it is most unlikely to be affected when the pressure load is reduced, and horizontal cracks are less likely to occur. When the forming die is formed into a conical shape or a truncated cone shape, it is appropriate that the taper angle is 30 ° to 80 ° with respect to the central axis. If it is smaller than this range, it is easily broken, whereas if it is too large, horizontal cracks are likely to occur, which is not preferable.

In the present invention, spheres, cones, and other expressions representing shapes do not refer only to strict geometric shapes, but also include those with some deformation such as unevenness, curvature, bending, and distortion.

The above-mentioned molding die is typically manufactured by molding a raw material powder containing graphite powder as a main component using pitch or the like as a binder, or machining a graphite block.
In the present invention, in which the void has the above-described forming die having the above-described shape, in the case of producing block-shaped super abrasive grains, particularly a diamond sintered body, the problem of yield reduction due to cracks is essentially solved. I was able to.

The molding die is provided with voids or cavities corresponding to the shape of the intended component. The maximum size of the vacant space that can be utilized essentially depends on the pressure resistance of the ultrahigh pressure device used, but in the uniaxial pressurizing device of the type used by the present inventors, such as high rigidity alumina, as a pressure damping material. It is possible to fabricate a cross section perpendicular to the axis up to a maximum dimension of 100 mm.

In addition to the above-described structure in which one end is open, the molding die has upper and lower split dies (upper die / upper die) having a horizontal (that is, vertical to the pressure axis) separation surface depending on the shape of the void to be formed. It can be configured to have a predetermined void in the combined state. Both molds are combined, and a sheet of metal such as nickel is wound around and fixed to the periphery. Superabrasive-grain-containing mixed powder, which is a starting material, is poured from an injection port provided at the top of the upper mold, and after the injection port is filled, it is closed with a lid made of the same or similar material as the mold material.

When the mold is constructed as a split mold,
5m deep so that the outer part of the mold is included in the opposite part of both molds
Providing a conical surface of about m is effective in securing the shape of the sintered product.

In the above, if the void portion can be processed, an integral type can be used instead of the split type.

Since the method of the present invention is particularly suited to the production of large-sized sintered body parts, its effect is more remarkable as the size becomes larger, but it can also be applied to small-sized parts if economic efficiency is not emphasized. From this viewpoint, the lower limit of the diameter of the opening of the mold is about 10 mm.

The diamond powder in the above starting material is 95 to 20% by volume with respect to the total volume, and the balance is metallic and / or
Alternatively, it is preferable to use a ceramic binder. The diamond content is appropriately set according to the desired characteristics (workability, hardness, etc.). That is, when workability is required, a composition containing a small amount of diamond is selected.

Co is preferred as the metallic binder. On the other hand, the ceramic binder typically uses metal carbide. This is TiC, WC or SiC alone or in combination, while as the metal material, Ti, W, Si, Co,
Ni or Cr can be used alone or in combination. The combination of WC and Co is a typical example.

It is also effective to add a slight amount of TiH ₂ to the starting material as a getter of oxygen or nitrogen.

The grain size of the diamond used in the present invention is not particularly limited, but in consideration of the subsequent processing steps and the final surface roughness, the grain size of 0.2 to 50 μm is generally preferable.

When loading into a press, the molding die is usually constructed as described above, the starting material is filled therein, and a heater for electric heating and circuit components are arranged around the die to suit the press to be used. The above composition is surrounded by a pressurized medium such as forsterite or sodium chloride, and then subjected to ultrahigh pressure and high temperature condition operation.

In the case of the one-end open type, two such molds and a heat-resistant and pressure-resistant partition plate are prepared, and after filling each of the molds with the powder of the starting material, each opening is opened. By arranging them so that they face each other and via the partition plate, it is possible to simultaneously subject the two molding dies to ultrahigh pressure / high temperature condition operation to obtain two sintered body blocks.

The sintered block recovered from the ultra-high pressure and high temperature operation is further processed into a final shape by electric discharge machining, if necessary.

In each of the above constructions of the present invention, other superabrasive grain species, in particular cubic boron nitride (c-
BN) can also be made into a sintered body block by the same operation by using a known suitable binder.

Next, the present invention will be described with reference to examples.

[0024]

Example 1 93 g of an IRM grade synthetic diamond (manufactured by Tomei Diamond) having a nominal particle size of 20/30 μm, cobalt powder having a particle size of 2 μm, 54 g and TiH ₂ having a particle size of 6 μm were put into a ball mill and sufficiently mixed to obtain a starting material. In this case, the volume ratio of diamond to cobalt corresponds to 80:20.

On the other hand, as shown in FIG.
mm, length of 25 mm, the ends of two graphite cylinders, diameter 30 mm
Hollow into a hemispherical shape to make split molds 11 and 12,
Further, a through hole 13 having a diameter of 10 mm was opened in one of the holes to form an injection port. Both split molds 11 and 12 are provided with respective voids 14,
15 were made to face each other and assembled, and a nickel foil 16 was wound around and fixed. After the starting material mixed powder 17 was filled from the hole 13 at the top of the mold, the hole was closed with a plug 18 made of graphite.

The combined starting material aggregate A was mixed with 10 ⁻⁵ Torr.
After heat treatment under reduced pressure for 3 hours, as shown in FIG.
Put it in a sleeve 21 made of salt (NaCl) and put ceramics on top and bottom
(Forsterite type) discs 22 and 23 and salt disc 2
4, 25 were arranged. The whole is packed in ceramic sleeves 27-29 via a metal ring 26, around the heater 30 consisting of a stainless steel sleeve, and also for the circuit construction steel rings 31, 32 and a disc 33, respectively.
34, and steel cylinders 35, 36 for energization and ceramic rings 37, 38 for insulation.

The whole was loaded into an ultra high pressure device. The pressurizing axes were aligned and subjected to pressure and temperature conditions of 5 GPa and 1500 ° C. to complete sintering.

After cooling and depressurization, a crushed elliptic spherical block having a diameter of 34 mm and a thickness of 18 mm, but no crack was observed, was recovered. This was further cut and lapped by WEDM processing and finished into a cube with a side of 14 mm, which was used as a material for an ultra-high pressure generating anvil.

[0029]

Example 2 One graphite cylinder of the above example was used.
As shown in Fig. 4, hollow the central axis of the cylinder to a depth of 10 mm from the end face into a cylindrical shape with a diameter of 20 mm and a bottom of the hole of 20 mmφ.
It was cut into a hemispherical shape to obtain a molding die 41. The void portion of this mold was filled with a starting material mixed powder 42 consisting of a diamond of 8/16 μm and a 92: 8 (volume ratio) mixture of tungsten carbide and cobalt (superhard powder), and a diameter of 20 mm on the top. Thickness 10
A cylindrical support body 43 made of carbide and having a thickness of mm was placed. A heater was placed in the surroundings, surrounded by a pressure medium, and subjected to the same operation as in Example 1. The obtained sintered body block had a semi-elliptical spherical shape integrated with a superhard support.

[0030]

According to the present invention, a three-dimensionally shaped superabrasive grain sintered body having a significantly larger size than the conventional one can be obtained with a high yield. Therefore, it has been difficult to realize an anvil for a large-sized ultrahigh pressure apparatus. Molds of hard materials and the like will be available. Further, since it is also suitable as a constituent material for various blade tools, for example, a glass fiber cutter, a scriber, etc., it is possible to greatly improve the tool life of these tools.

[Brief description of drawings]

FIG. 1 is an elevation view showing an example of a three-dimensional shape to which the present invention is applicable.

FIG. 2 is a cross-sectional view showing one structural example of a molding die used in Examples.

FIG. 3 is a sectional view showing an example of an assembly for a sintering operation used in Examples.

FIG. 4 is a cross-sectional view showing another configuration example of the molding die used in the examples.

[Explanation of symbols]

11, 12 split mold 13 through holes 14, 15 void 16 Nickel foil 17 Starting material mixed powder 18 Graphite disk 21 salt sleeve 22,23 Ceramic disk 24, 25 salt discs 26 metal rings 27-29 Ceramic Sleeve 30 heater 31, 32 Steel ring 33,34 Steel disk 35, 36 Steel cylinder 37, 38 Ceramic ring 41 Mold 42 mixed powder of starting materials 43 Carbide support

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 3/14 550 C09K 3/14 550D 550F 550H C22C 1/05 C22C 1/05 D E G MP 19 / 07 19/07 Z 26/00 26/00 29/02 29/02 29/16 29/16 A

Claims (23)

[Claims] 1. A superabrasive grain sintered body which is sintered under a uniaxial pressure pressure under a pressure temperature condition in which the superabrasive grain is thermodynamically stable, and the sintered body has a pressure direction. Of the maximum length (axial length) and the maximum dimension (section length) perpendicular to the pressing direction, whichever is smaller, has a three-dimensional shape of 10 mm or more, and the larger one has a three-dimensional shape of 20 mm or more. block. 2. The superabrasive grain sintered body block according to claim 1, wherein the three-dimensional shape has an axis of symmetry parallel to the pressing direction. 3. The superabrasive grain sintered body block according to claim 2, wherein the three-dimensional shape is one selected from a sphere, an ellipsoidal sphere, a cylinder, a cornerless cylinder, a cone, a truncated cone, and a combination thereof. . 4. The sintered body has a volume of 95 to 95.
The superabrasive grain block of claim 1 containing 20% superabrasive grain particles and the balance binder phase. 5. The binder phase contains WC and Co,
The superabrasive grain sintered body block according to claim 3. 6. The superabrasive sintered body block of claim 3 wherein said binder phase consists essentially of metal Co. 7. The superabrasive grains are diamond or c-BN.
The superabrasive grain sintered body block according to claim 1, which is 8. The superabrasive grain sintered body block according to claim 1, wherein the superabrasive grains are diamond grains having an average grain size of 0.2 to 50 μm. 9. (1) A mold is prepared which is made of a heat-resistant material and has an inner surface-shaped void portion whose cross-sectional area decreases from the opening to the bottom portion. Of the maximum length in the pressure direction (axial length) and the maximum dimension perpendicular to the pressure direction (section length), the smaller one has a solid shape of 10 mm or more, and the larger one has a solid shape of 20 mm or more. The starting material is constituted as a uniform and dense mixed powder containing superabrasive powder and binder raw material powder, and (3) the starting material is put into the above-mentioned molding die, and the opening is closed with a heat and pressure resistant block. Also, after arranging a heater for electric heating around the periphery, (4) load the whole into a uniaxial pressure press, align the center axis of the mold with the pressure direction, and (5) superabrasive the above starting materials. The particles are subjected to pressure and temperature conditions in a thermodynamically stable region to be sintered and integrated to form a sintered block. (6) A method for producing a superabrasive grain sintered body block, which comprises recovering the sintered body block after cooling and releasing the pressure. 10. The method according to claim 9, wherein the inner surface shape is a cone or a truncated cone having an inclination angle of 30 ° to 80 ° with respect to the central axis. 11. The method of claim 9, wherein the inner surface shape comprises a spherical portion. 12. The inner surface shape includes an annular surface portion,
The method according to claim 9. 13. The method according to claim 9, wherein the heat and pressure resistant block is made of a cemented carbide, and the superabrasive grain sintered body block is integrated with the heat and pressure resistant block and recovered. 14. The opening of the mold has a diameter of 10 to 100.
The method according to claim 9, which exhibits an essentially circular shape of mm. 15. (1) A mold is prepared which is made of a heat-resistant material and has a three-dimensional inner surface-shaped void and an injection port connected to the void. Of the maximum length (axial length) and the maximum dimension (section length) perpendicular to the pressing direction, the smaller one is 10 mm or more, and the larger one is 20 m.
(3) the starting material is formed as a uniform and dense mixed powder containing a superabrasive powder and a binder raw material powder, and (3) the starting material is formed into the above-mentioned molding die. After putting in, closing the inlet with a heat resistant block and arranging a heater for electric heating around it, (4) load the whole into a uniaxial pressure press, and align the center axis of the mold with the pressure direction. Let (5)
The starting material is subjected to pressure and temperature conditions within a region where the superabrasive grains are thermodynamically stable to form a sintered body block by sintering and integration, and (6) after cooling and pressure release, the firing is performed. A method for producing a superabrasive grain sintered body block, which comprises collecting the bound block. 16. The mold comprises a horizontally separable upper mold and a lower mold made of a heat-resistant material, and in the state where the upper mold and the lower mold are combined, a void portion having an axisymmetric inner surface shape is formed. 16. The method of claim 15 having. 17. The method according to claim 9, wherein the mold cavity has an axially symmetrical inner surface shape. 18. The method according to claim 9, wherein the starting mixed powder contains 95 to 20% by volume of superabrasive powder and the balance is composed of metal carbide and / or metal. 19. The metal is at least one selected from TiC, WC and SiC, and the metal material is Ti,
At least 1 selected from W, Si, Co, Ni, and Cr
19. The method of claim 18, which is a seed. 20. The method according to each of claims 9 and 15, wherein the heat-resistant material constituting the mold has non-diamond carbon as a main component. 21. The recovered sintered body block is further provided with:
The method according to each of claims 9 and 15, which is formed into a predetermined shape by electrical discharge machining. 22. The method according to claim 9, wherein the superabrasive particles are diamond particles having a particle size of 0.2 to 50 μm. 23. The method according to claim 9, wherein the starting material contains a trace amount of TiH ₂ .