JP7533872B2 - Method for manufacturing diamond-based block tool blanks - Google Patents

Description

The present invention relates to a high-hardness block tool material in which the constituent diamond particles and transition metal carbides are firmly bonded and integrated with each other.

The present invention particularly relates to a hard sintered material in which diamond particles are strongly bonded to each other through the interposition of carbides of one or more metals selected from Groups 4, 5, and 6 of the periodic table, thereby resulting from the strong affinity between the transition metal carbide and diamond. The present invention also relates to a hard sintered material in which diamond particles are strongly bonded to each other through the interposition of carbides of one or more metals selected from Groups 4, 5, and 6 of the periodic table or iron group metals, thereby exhibiting appropriate electrical conductivity or resistivity based on the electrical properties of such compounds.

The present invention also relates to a method for producing such sintered materials, in particular, a diamond-based block tool material aggregate that can be used as a cutting tool element with excellent hardness and heat resistance for machining a wide variety of materials, including ferrous metals, and can be used in a wide range of cutting, grinding and polishing processes, and a method for producing the same.

The present invention relates to a diamond-based block tool material aggregate that is excellent in hardness and heat resistance as well as in machinability by electric discharge machining and can be used with current tool manufacturing methods as a cutting tool element, and a method for manufacturing the same.

Sintered bodies made by bonding powdered diamond, an abrasive with high hardness and excellent wear resistance, have been used to make cutting tool tips and the like. Such sintered bodies are also called polycrystalline diamond (PCD), and are generally made by melting cobalt (Co) under ultra-high pressure and temperature and allowing it to flow between the diamond powder particles, and the diamond powder is integrated by the dissolution and precipitation action through the molten liquid phase. The resulting sintered body is conductive because the cobalt is trapped inside, and when making cutting tools and the like, productivity can be increased by using electric discharge machining methods for processes such as surface finishing and cutting.

However, the binding material, cobalt, acts as a catalyst to graphitize diamond from around 700°C, and this effect becomes more pronounced as the temperature rises, so there is a problem with heat resistance, making it difficult to use under high temperature conditions due to the heat generated during cutting. There is also the problem that diamond itself is reactive with iron. Therefore, there is a need to overcome these problems inherent to diamond and develop a diamond mass that can be used as a cutting tip material that can utilize the extremely hard properties of diamond and can also be used to cut iron-based materials.

Methods for preparing diamond polycrystals (lumps) without using iron group metals such as cobalt are known. For example, a diamond sintered body is known in which a mixture of diamond particles and powder of a transition metal from groups 4a, 5a, or 6a is pressed and sintered as a binder, and the resulting mixture is integrated via metal carbide.

Patent Document 1 (JP Patent Publication 51-735112) describes a method in which diamond powder is mixed with metal powders such as titanium and zirconium, the metal is melted under high pressure and high temperature conditions in the diamond stability range, and the diamond powder is consolidated (sintered) via the metal carbide produced by reaction with the diamond, with a maximum sintering temperature of 1950°C being stated.

In addition, the method described in Patent Document 2 (JP Patent Publication 5-194032) shows a method in which diamond powder is mixed with metal powder such as titanium or zirconium, heated to 1700-1900°C to disperse the metal on the diamond surface, and then heated to 2000°C or higher to convert the metal into carbide by reaction with the diamond.

Furthermore, Patent Document 3 (JP Patent Publication 8-176696) discloses a method for manufacturing a composite sintered body in which diamond particles are mixed with transition metal powder such as titanium or zirconium, and heated to a temperature of 1300-1500°C, resulting in a solid-phase reaction between the diamond and the metal, resulting in a metal carbide in which the diamond particles are dispersed and fixed.

In each of the above known techniques, diamond powder or granular material is packed into a capsule together with a binder, then placed in a high-pressure, high-temperature device similar to that used to obtain diamond from graphite, and subjected to ultra-high pressure and high temperature, resulting in an integrated sintered body through static high-pressure, high-temperature processing.

Therefore, high-pressure, high-temperature equipment, which is required to simultaneously apply to the diamond raw material (high temperatures exceeding 1000°C necessary for sintering) and high pressures of 5 GPa or more at which diamond can exist in a thermodynamically stable phase for a certain period of time, has limitations on the processing volume and the dimensions and quantity of the sintered material to be processed, making it difficult to improve productivity.

In addition, the high-pressure, high-temperature equipment used in sintering has a short lifespan because high pressures and temperatures are repeatedly applied under conditions close to the limits of its durability, and the short lifespan of expensive equipment is one of the factors that increase product costs.

As a way to avoid the above-mentioned problems inherent to static methods using high-pressure, high-temperature equipment, particularly limitations on processing size and increased costs associated with the short lifespan of manufacturing equipment, attempts have been made to manufacture sintered bodies using dynamic high-pressure, high-temperature processing methods that use explosive impact or impact pressure. However, although the high impact pressure has been successful in densifying the mixed powder of starting materials, it has not been possible to bond the powder together to obtain an integrated sintered body.

The reason for this is that in the dynamic pressurization method that applies the explosive shock, the effective pressurization time is extremely short, on the order of microseconds, and although the temperature rises momentarily due to adiabatic compression, the temperature also drops as the pressure drops, so it is believed that the powder particles do not bond together through melting or diffusion.

Japanese Patent Publication No. 51-735112 Japanese Patent Application Laid-Open No. 5-194032 Japanese Patent Application Laid-Open No. 8-176696

R. G. McQueen et al. (1970) "The equation of state of solids from shock wave studies" in High-Velocity Impact Phenomena (ed. R. Kinslow) Academic Press, New York, pp. 293-300.

The present invention provides a revolutionary method that eliminates the above-mentioned problems associated with high-pressure, high-temperature processes based on conventional static and dynamic techniques, particularly the limitations on product size, and makes it possible to manufacture diamond sinters of any size and shape.

In the present invention, the manufacturing process for sintered bodies is divided into an earlier stage and a later stage, in which the mixed powder as the starting material is densified using a dynamic pressurization method in the earlier stage, and in the later stage, the mixed powder densified in the earlier stage is heat-treated to bond the powder mixture. By carrying out the pressurization treatment and heat treatment in separate steps in this way, it is possible to manufacture large diamond sintered bodies and process large quantities, and by eliminating the need for expensive static high-pressure/high-temperature equipment, it is possible to reduce costs and supply low-cost diamond sintered bodies.

The product of the present invention is a solidified body in which the starting material is compressed to 90% or more of its theoretical density by ultra-high impact pressure and then heat-treated, and contains 35 to 90% by mass of diamond particles. The diamond particles are bonded together via metal carbides, which are essentially formed by reaction with the binder metal, to become a highly tough diamond-based block tool material.

The above-mentioned block tool blank is achieved by the following method:
(1) A starting material, which is 35 to 90% by mass of diamond particles and the remainder is a powder of a binder-forming metal capable of forming carbide, is sealed in an implosion processing vessel;
(2) subjecting the container to ultra-high shock pressure to a density of 90% or more of the overall theoretical density;
(3) The diamond particles are then heat-treated at the heating temperature, and the surfaces of the diamond particles are bonded together with the newly formed particle surfaces by the impact pressure via the metal carbides that are generated in situ during the heat treatment.

That is, in the present invention, explosive shock or impact pressure of 1 GPa or more is applied to the mixed powder of the starting material to form a high density body, which is then heated and maintained at a temperature of 800°C to 1800°C, preferably 1000°C to 1500°C. This operation promotes the diffusion and wetting of Si added and mixed into the diamond powder in the starting material, one or more types of binder-forming metals selected from metals in Groups 4a, 5a, and 6a of the periodic table, and/or one or more types of preformed binder-forming metal species selected from ceramics such as carbides, borides, nitrides, and oxides, particularly one or more types of metals selected from Si, Ti, Zr, and Hf, between the diamond powder particles, and a dense, integrated sintered body is obtained through chemical bonding with the diamond particles and particle rearrangement due to the appearance of a molten phase.

In the present invention, the bonding mechanism between diamond and metals, or between metals, is considered to be bonding via compounds formed by the diffusion and wetting of solid or liquid phase metals between diamond powder particles. In addition, because an explosive shock is applied to the mixed powder of the starting material, cracks inevitably appear in the diamond, which is a hard and brittle material. However, when heated, the metal enters the gaps in the cracks and bonds to fill the cracks, resulting in bonding of diamond particles over an area larger than the original surface area of the diamond, resulting in high strength.

In addition, while diamond is very hard, it is also brittle and easily shattered by impact. However, because diamond is bonded with ceramics, which have a high toughness but a lower hardness than diamond, the diamond sintered body obtained by compression and heat treatment has a higher toughness than a sintered body made of diamond alone.

The ceramics such as carbides, borides, nitrides, and oxides of preformed metal species that form the binder that are added to the starting material are not expected to bond directly to the diamond particles, but they are expected to improve the physical properties of the binder phase, especially to contribute to toughness.

The reason why the explosive impact or impact pressure to be applied to achieve densification of the starting material is specified as 1 GPa or more is that it has been empirically shown that compression to the required density is not possible at less than 1 GPa.

The explosion pressure generated by an explosive is calculated using formula 1).
P= ρ ₀ DU _p・・・・・・・・・ 1)
where P is the detonation pressure, ρ ₀ is the density of the explosive at the time of filling, D is the detonation velocity, and U _p is the flow velocity of the explosive products.

U _p = D/4 ・・・・・・・・・・・・ 2)
Since it is known that it can be approximated by the following equation, equation 1) can be transformed into the following equation.
P= ρ ₀ D ² /4 ・・・・・・・・・ 3)

The pressure that a metal object colliding at high speed exerts on a metal container can be calculated using the following formula, if the metal object and the metal material that makes up the implosion processed container are the same.
P= ρ ₀ U _s U _p・・・・・・・・・ 4)
U _p = U _fs /2 ・・・・・・・・・ 5)
where _Ufs is the collision velocity.

Although it is relatively easy to measure the impact velocity _Ufs , it is difficult to measure the shock wave velocity _Us . For example, if the material of the metal container and the metal body that collide with each other is steel, the relationship between _Us and _Up is known, and
U _s = 3.574 + 1.920U _p - 0.068U _p ²・・・・・・・・・・・・ 6)
In the above, U _s and U _p are in units of km/s.

The method for calculating the pressure that occurs when a metal container and a metal body made of materials other than steel collide with each other or when objects made of different materials collide can be found in Non-Patent Technical Document 1.

The reason why the present invention requires compressing the mixture of diamond and metal powders (hereinafter referred to as the mixture) by impact to a density exceeding 90% of the aggregate density of the constituent materials is that at a density below that, even if the diamond and metal are bonded together by heat treatment, the necessary hardness and strength for a high-hardness sintered body containing diamond cannot be obtained.

The density in a compressed state is calculated by the ratio of the aggregate theoretical densities of the constituent materials to the density of the materials compressed into one body. In reality, the theoretical density and actual density of a ceramic material differ slightly because the actual atomic ratios that make up the ceramic differ slightly from the theoretical atomic ratios, but this does not cause any practical problems, so the theoretical density of each material is used in the calculation.

Below, the method for producing a high-hardness sintered body containing diamond or the like according to the present invention will be explained with reference to the attached drawings 1 to 3.

FIG. 1 is a vertical cross-sectional view showing an example of a configuration for simultaneously mass-producing three-dimensional sintered articles in a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a schematic of an explosive arrangement for housing the arrangement of FIG. 1 and performing explosive impact compression processing. FIG. 5 is a longitudinal sectional view taken along plane B-B of FIG. 4 below, showing an example of a configuration for producing a large-area plate-shaped sintered material that cannot be produced by a conventional static high pressure apparatus in a second embodiment of the present invention. FIG. 4 is a plan sectional view taken along the line AA of FIG. 3. FIG. 11 is a diagram showing a configuration for compressing mixed powder of starting materials by the impact of a metal plate flying due to explosion pressure in a third embodiment of the present invention.

In the figure, reference numeral 11 denotes a mixed powder molded body of starting materials including diamond, and 12 denotes a powder molded body of support material raw material that is placed adjacent to the diamond sintered layer and reinforces it. As the support material raw material, powders of WC-Co based cemented carbide and various cermet raw materials can be used.

The two powders are molded in advance into an integrated composite compact 13, which is then placed in a graphite mold 14 and filled into an implosion processing vessel 15, where they are simultaneously compressed and sintered, and taken out as a firmly bonded integrated product (composite material). The composite compact can be mass-produced by processing it alone or by arranging multiple compacts side by side, for example, in a cylindrical metal vessel or implosion processing vessel 15 as shown in Figure 1, simultaneously.

When the composite compacts housed in multiple graphite molds 14 are loaded into an implosion processing vessel, it is effective to place a plate or layer of separator 16 between adjacent graphite molds to prevent them from bonding to each other. The separator can be a heat-resistant material that does not sinter in the operation of the present invention, such as graphite, hexagonal boron nitride, or ceramic powder.

Both ends of the implosion processing vessel are closed with metal plugs 17, 18 to seal the contents, and cushioning materials 19, 20 are placed inside the plugs to prevent the metal plugs 17, 18 from affecting the contents when shock pressure is applied; these can be made of the same material as the separation material 16 described above.

The metal container containing the composite compact is then placed in an explosive container 21 made of metal, plastic, paper, etc. for implosion processing, and explosives 22 are packed around it. Any type and grade of explosive, such as dynamite, ANFO (ammonium nitrate oil explosive), or compound explosive, is appropriately selected and used depending on the required pressure. An electric detonator 23 for detonation is connected to the container 21, as well as a vacuum pipe 24 for evacuating the inside of the implosion processing container.

Figures 3 and 4 are layout diagrams for compressing the starting material diamond-containing mixed powder molding in a planar direction, and show the state in which the starting material mixed powder molding 31 is loaded into a mold between opposing metal flat plates 33, 34 for impact compression, and explosives are placed. A flat starting material mixed powder molding 31 is filled into a space cut in the thickness direction of a metal mold 32, and metal flat plates 33, 34 for compression of the same size as the starting material are laminated on both the top and bottom sides via graphite sheets 35, 36. The top and bottom sides of the metal mold 32 are covered with cushioning materials (e.g. graphite sheets) 37, 38 that also serve to prevent explosive bonding between metals, and impact compression plates 39, 40 are placed on the outside. It is preferable to place cushioning and separation materials 41 on the sides of the mold 32 as well.

This structure is stacked in multiple layers (two layers in the figure) with graphite sheets in between, and the whole is placed in an airtight plastic bag 42. The bag is thoroughly evacuated through a vacuum pipe 43, and the pipe is crushed to vacuum seal it. This is then sandwiched between explosives 45 packed in an explosive container 44, and an electric detonator 46 for detonation is attached.

5, the explosion of explosive 52 filled in explosive container 51 causes metal flying plate 53 placed on the underside of the explosive to fly at high speed and collide with metal cover 56 of metal receiving stand 55 containing mixed powder molded body 54 of starting material, thereby applying impact pressure. Explosive container 51 and flying plate 53 are supported by cylindrical body 57 such as paper, and are detonated by electric detonator 58.
The following examples are provided to illustrate the embodiments of the present invention.

The bit components shown in Figures 1 and 2 were manufactured. The graphite mold that contained the starting material had an outer diameter of 25.5 mm and a length of 30 mm, and the inner dimensions of the mold were a cylindrical section with a diameter of 20 mm and a length of 17 mm, and a hemispherical section with a length of 10 mm. The tip where the load is applied was made of a diamond-TiC material, and the cylindrical section of the support was made of a WC material.

The mixed powder for the tip material was prepared by weighing out 50% by mass of diamond (IRM 8-20, Tomei Diamond Co., Ltd.) with an average particle size of 12 μm, 45% by mass of TiC powder (TiC1-2, Nippon Shin Kinzoku Co., Ltd.) with an average particle size of 2 μm or less, and 5% by mass of carbonyl nickel powder (T123, Vale) with an average particle size of 4 μm, and mixing them in a wet ball mill using acetone for 2 hours, followed by vacuum drying at 600°C for 2 hours. The mixed powder for the cylindrical part of the support was prepared by mixing 87% by mass of WC powder and 13% by mass of Co powder in a wet ball mill for 2 hours, followed by vacuum drying at 600°C for 2 hours.

A metal mold with the same internal dimensions as the graphite mold was prepared, and 6.0 g of diamond-containing mixed powder was packed into the hemispherical tip of the mold by tamping, then 54 g of WC-based material was added and the mold was compressed to 70% of the theoretical density.

The steel pipe for implosion processing had an outer diameter of 30.0 mm, an inner diameter of 26.0 mm, and a length of 250 mm, and six molded products were arranged in series around the axis of the steel pipe. A 9 mm alumina layer was sandwiched between both ends and sealed with steel plugs, and the inside of the steel pipe was vacuum-sealed by evacuating the air via a vacuum-drawn copper tube. The bottom of the cylindrical part in contact with the alumina layer was partitioned off with a 1.6 mm thick mild steel plate with a 0.5 mm graphite sheet in between.

This steel pipe for implosion processing was placed at the center of an explosive cylinder with an outer diameter of 120 mm and a length of 330 mm, which was housed in a paper cylinder. The explosive was in powder form, and when it was detonated by an electric detonator, it exploded at an explosion speed of 2340 m/s. The explosive packing density was 0.92 g/ ^cm3 , and when the numerical value was applied to the formula 3), the estimated explosion pressure was equivalent to 1.26 GPa.

The outer diameter of the metal tubes recovered after the explosion treatment, excluding the steel plugs, had shrunk to an average of 27 mm. The metal tubes still containing the contents were heated to 1350°C in a heating furnace, held there for two hours, then slowly cooled for one hour, and the steel tubes used for the implosion process were removed by lathe cutting.

The sintered product that was extracted was a dense product with a diameter of approximately 17 mm, a total length of approximately 26 mm, and a theoretical density of approximately 96%. The outer circumference of the cylindrical part was polished to φ16 mm by centerless grinding, making it suitable for practical use.

Two sets of flat sintered bodies were produced with the configuration shown in Figures 3 and 4. For the first set, 49 mass% of diamond powder with an average particle size of 70 μm (IMS 200/230, manufactured by Tomei Diamond Co., Ltd.), 21 mass% of diamond powder with an average particle size of 3.5 μm (IRM4-6, manufactured by Tomei Diamond Co., Ltd.), and 30 mass% of silicon powder (ground high-purity chemical products) with a particle size of 1 μm or less were weighed out and press-molded to an average thickness of 6 mm, width of 39 mm, and length of 79 mm to produce a mixed powder molding with a filling density of 75% of the theoretical density.

The second set was a mixture of 50% by mass of diamond powder with an average particle size of 9 μm (IRM8-16, manufactured by Tomei Diamond Co., Ltd.), 40% by mass of TiC powder with an average particle size of 2 μm or less (TiC1-2, manufactured by Nippon Shinkinzoku Co., Ltd.), 5% by mass of _Mo2C powder with a particle size of 1-2 μm (manufactured by Nippon Shinkinzoku Co., Ltd.), and 5% by mass of carbonyl nickel powder with an average particle size of 4 μm (T123, manufactured by Vale).As with the first set, this was pressed into an average thickness of 6 mm, width of 39 mm, and length of 79 mm to produce a mixed powder compact with a filling density of 72% of the theoretical density.

The metal form for impact pressure was 55 mm wide, 90 mm long and 8 mm thick, and the mixed powder molding was placed in a cut-out section inside measuring 40 mm wide and 80 mm long. 2 mm thick mild steel plates were fitted as backing plates, with graphite sheets of the same dimensions and 0.5 mm thick placed above and below. 3 mm thick graphite sheets of the same dimensions as the form were placed above and below this backing plate, and the plate was sandwiched between 3.2 mm thick mild steel plates for impact pressure.

Two sets of assemblies constructed as described above were stacked with a 6 mm thick graphite sheet in between, and the whole was placed in a plastic bag, evacuated via a vacuum pipe, and the bag was vacuum-sealed.

A 25mm thick gelatinous dynamite was placed on the top and bottom of the above structure, and detonated from one end with an electric detonator. The explosion velocity was 4100m/s, the explosive density was 1.38g/ ^cm3 , and the generated pressure was estimated to be 5.8GPa from formula 3). The two assemblies were separated at the graphite sheet at the boundary and were collected separately.

The above-mentioned materials recovered from the implosion process were heated in a hydrogen atmosphere for two hours, with the first assembly at 1450°C and the second assembly at 1300°C, and then allowed to cool and removed at below 100°C. The mild steel plates sandwiching the sintered layer on both sides were removed by grinding, and any slight waviness that occurred during pressing was flattened by grinding to obtain a flat plate measuring 4 mm in thickness, 41 mm in width, and 82 mm in length.

The desired shape and size of cutting chip material could be cut out from this flat plate using wire cutting.

The micro Vickers hardness of the plates was measured at 10 points in the center and 10 points on the periphery, and it was found to be in the range of 37-39 GPa for the first assembly and 40-42 GPa for the second assembly, which is satisfactory for practical use.

A sintered body was manufactured using an impact pressure method having the configuration shown in FIG.
A paper cylinder with an inner diameter of 20 mm and a height of 40 mm was used as the explosive container. 14 g of powder explosive was placed in the bottom of the cylinder, and a copper disk with a thickness of 2 mm and a diameter of 20 mm was placed. The starting material was a mixed powder molded into a disk-shaped pellet with a diameter of 18.9 mm and a thickness of 6 mm, which was filled into a depression with a depth of 8 mm and a diameter of 20 mm in the center of a steel support with a diameter of 30 mm and a height of 13 mm. A graphite sheet with a thickness of 0.5 mm was placed between the peripheral wall and the bottom of the pellet. The depression was covered with a copper disk lid.

The starting powder mixture was prepared using the following ingredients:
Diamond: average grain size 12μm (IRM 8-20, manufactured by Tomei Diamond Co., Ltd.)
Si: Particle size 1μm or less (ground from high-purity chemical products)
Ti: Grain size 45μm or less TSPT (Osaka Titanium Technologies Co., Ltd.)
Zr: Particle size 45μm or less Reagent Hf: Particle size 45μm or less Reagent
Nb: Particle size 45μm or less Reagent
Ta: Particle size 45μm or less Reagent TiC: Average particle size 2μm or less (TiC1-2, manufactured by Nippon Shinkinzoku Co., Ltd.)
TaC: Average particle size 2μm (manufactured by Nihon Shinkinzoku Co., Ltd.)
TiN: Average particle size 2μm (TiN-02, manufactured by Nippon Shinkinzoku Co., Ltd.)
TiB ₂ : Particle size 2.5 to 45 μm (TiB ₂ -N, manufactured by Nihon Shinkinzoku Co., Ltd.)
_ZrO2 : Particle size 10μm or less (manufactured by Fukushima Steel Works, Ltd.)

In the above configuration, the powder explosive was exploded by passing electricity through the electric detonator, propelling the copper flying disk at the bottom of the explosive container and causing it to collide with the copper disk lid covering the mixture at a speed of 420 m/s. The pressure generated by the collision was estimated to be 7.98 GPa, calculated based on formulas 4), 1), and 6). The part covered by the copper disk sank into the recess in the steel support due to the collision pressure.

The recovered treated material was heated to 1350°C in a nitrogen atmosphere, held for 2.5 hours, slowly cooled in the furnace, removed and turned to obtain a sintered mixture. Approximately 2 mm was removed from the outer periphery of the mixture by grinding, and the top and bottom surfaces were also finished to be smooth, yielding a strong sintered body with a diameter of 16 mm and a thickness of 4 mm. The Vickers hardness of each sintered body obtained is shown in Table 1, along with the compounding ratio of the starting materials.

11 Starting material mixed powder molded body 13 Composite molded body 14 Graphite mold 15 Implosion processing container 16 Separation material 17, 18 Metal plug 19, 20 Cushioning material 21 Explosive container 22 Explosive 23 Electric detonator 32 Metal mold 33, 34 Metal flat plate 35, 36 Graphite sheet 37, 38 Cushioning material (e.g. graphite sheet) that also serves to prevent explosive adhesion
39, 40 Impact pressure plate 41 Cushioning/separating material 42 Plastic bag 44 Explosive container 45 Explosive 46 Electric detonator 51 Explosive container 52 Explosive 53 Metal flying plate 54 Mixed powder molding 55 Metal receiving base 56 Metal lid 57 Paper or other cylinder 58 Electric detonator

Claims (13)

(1) A starting material consisting of a mixture of 35 to 90% diamond particles by mass and the remainder being a powder of a binder-forming metal capable of forming carbide is sealed in an implosion processing vessel;
(2) subjecting the container to ultra-high shock pressure to bring the density of the entire starting material to 90% or more of the theoretical density;
(3) The container containing the contents is then subjected to a heat treatment at a temperature between 800°C and 1800°C, inclusive, to bond and integrate the diamond particle surfaces and the newly generated particle surfaces due to the impact pressure via the metal carbide formed in situ during the heat treatment.
A method for producing a diamond-based block tool blank. The method for producing a diamond-based block tool blank according to claim 1, wherein the starting material further contains one or more preformed bond-forming metal species selected from borides, nitrides, carbides, and oxides. The method according to claim 1 or 2, wherein the binder-forming metal species includes one or more selected from Si, Ti, Zr, and Hf. The method according to claim 1, wherein the shock ultra-high pressure is 1 GPa or more. The method of claim 1, wherein the implosion vessel is an axially elongated cylinder, and the starting material is radially and axially pressurized by the detonation of an explosive disposed along the outer periphery of the vessel. The method of claim 1 or 5, wherein the cross section perpendicular to the axis of the implosion vessel is circular or polygonal. The method according to claim 1, in which the starting material is placed in an implosion processing vessel, sandwiched or enclosed between a pair of opposing flat plates, and shock-compressed by detonating an explosive on the back surface of one or both of the flat plates. The method according to claim 1, in which the starting materials are stored in a plurality of implosion processing vessels, stacked and sandwiched between a pair of opposing flat plates, and explosives are detonated on the backs of the flat plates to shock-compress the starting materials. The method according to claim 8, in which a pressure-resistant plate-like body is placed on the axis of the implosion processing vessel, and the starting material is pressurized by causing the plate-like body to fly and move in the axial direction at high speed by the explosion of an explosive. The method of claim 1, wherein the starting material is a powder compact, and a cross section perpendicular to the axial direction of the compact varies along the axis. The method according to claim 1, wherein the heating temperature is 1000°C or more and 1500°C or less. The method of claim 1, wherein the starting material is placed in a container adjacent to the shaped support material raw material, and the two are joined by shock loading from the detonation of an explosive. 13. The method of claim 12 , wherein the support material feedstock is a mixed powder compact of a cemented carbide composition.

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