JPH0138841B2 - - Google Patents

Description

[Detailed description of the invention]

Cubic boron nitride (Cubic BN, hereinafter abbreviated as CBN) is a material with the second highest hardness after diamond, and is synthesized under ultra-high pressure and high temperature. Currently, it is already used as abrasive grain for grinding, and for cutting purposes,
Sintered bodies made by bonding CBN with metal Co, etc. are used in some parts. When this sintered body of CBN bonded with metal is used as a cutting tool, the bonding metal phase softens at high temperatures, resulting in a decrease in wear resistance, and the workpiece metal tends to weld, causing damage to the tool. There are drawbacks. The present invention relates to a new CBN sintered body suitable for tool applications such as cutting tools, which has a binder phase of a hard metal compound with high strength and excellent heat resistance, rather than a sintered body bonded with such metals. be. As mentioned above, CBN has high hardness, heat resistance,
It is a material with excellent wear resistance. Various attempts have been made to sinter only CBN; for example, as described in Japanese Patent Publication No. 39-8948,
It is over 70kb and needs to be sintered under ultra-high pressure and high temperatures of over 1900℃. Current ultra-high pressure and high temperature equipment can generate such high pressure and high temperature conditions, but if the equipment is scaled up on an industrial scale, it is not practical because the number of lifetimes of the high pressure and high temperature generating section is limited. Furthermore, although a sintered body made only of CBN has high hardness, it has poor toughness when used as a tool. The inventors used CBN as a binder from periodic table 4a.
By using compounds that mainly contain transition metal carbides, nitrides, carbonitrides, and Al, and containing Cu and iron group metal elements, and by finding more appropriate manufacturing conditions, We were able to obtain a highly hard sintered body with a CBN content of over 80% by volume, which has unprecedented wear resistance and toughness. A similar study was also conducted on wurtzite boron nitride, which is another form of high-pressure phase boron nitride, and results similar to those obtained using CBN were obtained. Details will be given below regarding a sintered body using CBN as a hard wear-resistant component, but the same can be said when using a wurtzite type or a mixture of CBN and wurtzite type boron nitride. An object of the present invention is to obtain a highly hard sintered body for tools with a high CBN content.
This makes it possible to take full advantage of the characteristics of CBN and apply it to, for example, tool materials for cutting high-hardness materials such as WC-based cemented carbide, as well as wire drawing dies. As mentioned above, a sintered body made only of CBN has drawbacks such as difficulty in manufacturing and insufficient strength of the sintered body itself. Therefore, it is possible to improve these defects by adding an appropriate binder to CBN. One of the known methods is a method using a metal bonding material, an example of which is a commercially available sintered body of CBN bonded with metal Co or the like. Also, attempts have been made to mix CBN with compounds other than metals, such as Al ₂ O ₃ and B ₄ C, and sinter the mixture. The former method is a liquid-phase sintering under high pressure, in which sintering is carried out at a temperature that melts a metal binder such as Co. In the latter case, the binder is not dissolved but sintered in a solid state.
The inventors previously discovered that using carbides, nitrides, borides, and silicides of metals of Groups 4a, 5a, and 6a of the periodic table as binders, these binder compounds formed a continuous binder phase in the structure of the sintered body. Invented a sintered body for high-hardness tools containing 40 to 80% by volume of CBN, and filed a patent application (Japanese Patent Application Laid-Open No. 77811/1983). In this case as well, sintering is performed in a solid state, but because the binder content is relatively high, the pressure and temperature conditions required to obtain a dense sintered body are higher than when sintering only CBN. eased. The inventors further investigated products with a higher content of CBN. If the CBN content exceeds 80% by volume, CBN and
Even if compound powders of group 4a, 5a, and 6a metals were sufficiently uniformly mixed and sintered under ultra-high pressure and high temperature, a high-strength sintered body could not be obtained. When we examined the fracture surface of this sintered body, we found that there were many fractures between CBN particles and between CBN and binder compound particles, which suggests that the bond strength between CBN particles or between CBN and binder crystal particles is low. It will be done. When the content of CBN is high, the sinterability decreases as described above, and a high-strength sintered body cannot be obtained. In order to improve this, we conducted more extensive experiments and found that when M represents carbides, nitrides, and carbonitrides of group 4a of the periodic table, especially transition metals of group 4a, as binders, MCx ,MNx,M(CN)
If a mixed powder containing Al, Cu, and iron group metals is used as a powder where the value of I found out what I can get. Carbides, nitrides, and carbonitrides in Group 4a of the periodic table are represented by the phase diagram of TiN in Figure 1.
Phases with NaCl type structure are M-C, M-N, M-
CN exists in a wide range of compositions. When the value of x was 1 or less, that is, by using CN with a relatively high atomic vacancy concentration, sinterability was improved. In addition, MCx, MNx, M
It was confirmed that the sinterability was improved when an Al compound was added to (CN)x compared to when only (CN)x was used. In addition, trace amounts of Cu, Fe, Ni, and Co
It was found that the sinterability was further improved when iron group metal elements were contained, and the strength of the sintered body was also improved. MCx used as binder raw material,
The preferred range of the value of x for MNx, M(CN)x is
It is 0.95 or less. Further, when Al is present in the binder in an amount of 5% or more as an Al element, and Cu and iron group metals are present in the binder in a total amount of 1% or more of these metal elements, a high-strength sintered body can be obtained. The CBN content in the sintered body is 85% by volume, and MCx, MNx, M(CN)x
As a result of prototyping sintered compacts with various values of is when the value of x is 0.50 to 0.95
The amount of Al added was in the range of 5 to 30% by weight in the binder, and the total amount of Cu and iron group metals added was in the range of 1 to 20% by weight in the binder. In the sintered body of the present invention, high-pressure phase boron nitride is present in a volume percentage of more than 80% and less than 95% in the sintered body. Within this composition range, in a sufficiently dense sintered body, the higher the CBN content, the higher the hardness of the sintered body. If it exceeds 95%, a decrease in the toughness required for a sintered tool will be observed. Furthermore, if the content is less than 80%, the binder phase of the sintered body forms a continuous phase in the structure, resulting in a decrease in hardness. Let us consider why the sinterability of high-pressure phase boron nitride is improved when the binder according to the present invention is used. For example, taking TiNx as an example, the hardness of a sintered body of only TiNx at room temperature is when the value of x is approximately 0.7.
Maximum. However, at high temperatures, the lower the value of x, the greater the degree of decrease in hardness. When CBN and TiNx are mixed and sintered under ultra-high pressure and high temperature, CBN crystals are difficult to deform, but TiNx particles can easily deform. For the reasons mentioned above, in this case, TiNx with a higher concentration of nitrogen atoms and a lower value of x is more likely to deform.
The same can be said of other MCx, MNx, and M(CN)x, which tend to penetrate between CBN crystal grains and become densified. However, this alone does not provide sufficient bonding strength between CBN particles. For example, in liquid phase sintering of WC-Co cemented carbide, if hard particles are dissolved into the binder phase and re-deposited, a product with high bonding strength between the binder phase and the hard particles, or between the hard particles can be obtained. . In the sintered body of the present invention, it has been found that a phenomenon similar to this occurs when an Al compound is present in the binder. as a binding material
When an Al compound is added to MCx, MNx, and M(CN)x, the sinterability improves as the amount increases, and a sintered body with high hardness can be obtained even when sintered at a low temperature. When the sintered body is polished with a diamond grindstone and then lap-finished and observed, almost no CBN particles are observed to fall off when the amount of Al added is 5% or more by weight of the binder. However, when observing the fracture surface of the sintered body, it was found that most of the CBN particles had undergone intragranular fracture, but some areas had intergranular fracture. this
A sintered body was prepared by adding Cu and a small amount of iron group metal to the composition of a CBN sintered body, and when the fracture surface was observed, no grain boundary fracture was observed. The reason for this is presumed as follows. Cu and iron group metals are MCx, MNx, M(CN)x in the sintered body.
reacts with excess M of the Group 4a transition metal to form a low melting point liquid phase, which uniformly infiltrates the interface between CBN and binders such as MC, MN, and M (CN). M-Cu and M-iron group metals that have penetrated into this interface have good affinity with CBN and the binder phase MC, MN, M (CN), so CBN-CBN or CBN-MC, MN, M
This is thought to be to increase the bonding strength of (CN). In addition, the sintered body containing Cu and iron group metals is made of CBN particles and binders such as MC, MN, and M (CN).
A large amount of boride such as MB ₂ is formed at the interface.
Borides such as MB ₂ are usually brittle and can cause destruction if present in large quantities. On the other hand, in a sintered body containing Cu and iron group metals, the formation of MB ₂ , etc. is suppressed, and therefore, in a sintered body containing Cu and iron group metals, CBN particles and the binder phase are firmly formed. It is thought that they were combined. Further, the sintered body of the present invention can be sintered at a low temperature because a liquid phase with a low melting point appears during sintering, as described above. In the sintered body of the present invention, these Cu and iron group metals do not exist as pure metals,
Because it exists as a solid solution in the binder phase of MC, MN, M(CN), etc., or reacts with excess M or Al of MCx, MNx, M(CN)x, and exists in the form of an intermetallic compound, No strength reduction occurs. However, when the content of Cu and iron group metals exceeds 20% by weight in the binder, Cu and iron group metals become MC, MN, M (C,
The hardness of the sintered body decreases because it exists in the sintered body in a pure metal state without forming a solid solution in the binder phase of N) or reacting with excess M and Al to form an intermetallic compound. decreases and tool performance deteriorates. Further, the ratio of Cu to iron group metal is preferably 1/2 to 5. If this ratio is less than 1/2, the Cu content is too low and the generation of boride cannot be suppressed.
On the other hand, if this ratio exceeds 5, the content of Cu increases and the hardness of the sintered body decreases. Various methods can be considered for processing Al or Cu and iron group metals. The simplest method is to add Al or Cu and iron group metals to the mixed powder with CBN before sintering, but it is difficult to obtain fine powders of these metals of 1μ or less, and coarse particles may affect the structure of the sintered body. tends to become uneven. In the case of Al, the most preferable method is to react metal Al in advance with the excess M of the binder MCx, MNx, M(CN)x to form an M-Al intermetallic compound, and use this by pulverization. It's a method. In this case, the binding materials MCx, MNx, M (C.
N) Extremely fine binder powder of 1μ or less consisting of an intermetallic compound of x and Al can be easily obtained. In addition, M-Al intermetallic compounds synthesized by reacting metal M and metal Al in advance (e.g. TiAl ₃ , TiAl,
Easily pulverized powders such as Ti ₂ Al, ZrAl ₃ , ZrAl, etc.) may also be used. AlN, another form of Al compound,
It may also be added in the form of a nitrogen-containing compound such as Ti ₃ AlN or Zr ₂ AlN. In addition, in the case of Cu and iron group metals, the most preferable method is to add them by diffusion from the outside of the sintered body during sintering, or by reacting with the binder as in the case of adding Al above. . The grain size of the CBN crystal used in the present invention needs to be 10 μm or less in view of the performance of the sintered body as a tool. If the crystal grains are coarse, the strength of the sintered body will decrease,
Moreover, especially when used as a cutting tool, a material with fine crystal grains provides a good machined surface. The particle size of the binder phase, which is another feature of the present invention, consists of extremely fine crystal grains of 1 μm or less.
As a result, the sintered body has a high CBN content, but
The binder phase is uniformly dispersed between the CBN particles, resulting in a high-strength sintered body. In producing the sintered body, we use an ultra-high pressure and high temperature equipment used for diamond synthesis to produce a sintered body under a pressure of 20 kb.
The above steps are carried out at a temperature of 900°C or higher. Particularly preferred sintering pressure and temperature conditions are pressure 30kb to 70kb and temperature 1100.
℃~1500℃. The upper limits of these pressure and temperature conditions are both within the range of practical operating conditions for ultra-high pressure and high temperature equipment on an industrial scale. Furthermore, the pressure and temperature conditions must be within the stable range of high-pressure phase type boron nitride shown in FIG. When using such an excellent sintered body as a cutting tool, the high hardness sintered body only needs to be used in the part that will become the cutting edge. Its performance can be fully demonstrated by bonding it to hard metal. However, if it is directly bonded to cemented carbide, the bonding strength is weak and it cannot be used for interrupted cutting.
To obtain sufficient joint strength, CBN is added by 30% by volume.
Contains more than 70% and the remainder is Ti, Zr,
Hf carbide, nitride or carbonitride or a mixture thereof or a mutual solid solution compound,
Bonding is performed using an intermediate layer containing 0.1 to 30% by weight of Al or Si. If this intermediate bonding layer contains 70% or more of CBN by volume, the bonding strength with the cemented carbide becomes weak, and if it contains less than 30%, the thermal shock resistance decreases.
The reason for this is thought to be that the difference in thermal expansion coefficients between the cemented carbide, the intermediate bonding layer, and the sintered body for tools becomes large. Further, Al and Si are effective in improving the sinterability of the intermediate bonding layer itself, but if it is less than 0.1% by weight, this effect cannot be obtained, and if it exceeds 30% by weight, the sinterability does not improve much. This will be explained in more detail below with reference to Examples. [Example 1] A mixed powder consisting of 90% by volume CBN particles with an average particle size of 3 μm and binder powder was prepared. The binder powder consists of TiN _0.83 powder and Al powder at 80% and 20% by weight, respectively.
% of the mixture was heated in a vacuum furnace at 1000°C, 30°C.
It was heated for a minute and then ground to a fine powder with an average particle size of 0.3μ. When this binder powder was examined by X-ray diffraction, it was found that in addition to TiN, Ti ₂ AlN, TiAl ₃ , TiAl
Compounds produced by the reaction of TiN and Al were detected, but metallic Al was not detected. this is
TiN Relative excess Ti added to N of _0.83
It is produced by reaction with Al. This mixed powder of CBN and binder was mixed with an outer diameter of 14 mm.
A cemented carbide with a WC-6%Co composition (outer diameter
10mm, height 22mm) and then filled with 0.30g.
A cemented carbide (outer diameter 10 mm, height 2 mm) on which 9Cu-1Ni alloy was vapor-deposited with a thickness of 2 μ was placed on top of this, a Mo stopper was placed, and the entire container was placed in an ultra-high pressure device used for diamond synthesis. . It was pressurized to a pressure of 50 kb, then heated to a temperature of 1250°C and held for 20 minutes. The removed sintered body was polished using a diamond grindstone.
The cemented carbide coated with Ni was ground until a high-hardness sintered body appeared, and then polished using diamond paste. When observed under an optical microscope, it was found to be a dense sintered body with no pores. This sintered body
The average particle size of CBN was 3.5μ, and the bonded particle size in the binder phase was mostly 1μ or less. This sintered body was firmly bonded to the cemented carbide via the CBN-containing bonding layer. Load 5 using a Bitkers hardness tester
The hardness was measured in kg and showed a value of approximately 4800. In addition, when we examined the elements contained in the sintered body using an X-ray microanalyzer, we found that Cu and Ni were evenly contained, and the total amount of Cu and Ni was approximately 3% of the weight of the binder. Ta. Furthermore, the products of this sintered body were investigated by X-ray diffraction and the results showed that CBN, TiN, AlN.
However, only a small amount of borides such as TiB ₂ were detected. Incidentally, a sintered body containing no Cu or iron group metals was produced in the same manner, and the product was
The product was investigated by line diffraction, and was found to be CBN,
In addition to TiN and AlN, a large amount of TiB ₂ was present.
Chips for cutting were made using these two types of sintered bodies. The work material is WC with a Bitkers hardness of approximately 1200.
-Choose a plastic processing punch made of 15% Co cemented carbide, cutting speed 18 m/min, depth of cut 0.2 mm, feed 0.1
Cutting was performed for 20 minutes at mm/revolution. For comparison, when we observed the wear of a chip made from a commercially available sintered body containing about 90% CBN by volume and bonded with a metal mainly composed of Co, we found that the flank surface of the sintered body of the present invention was the largest. The wear width was 0.10 mm, while that of the sintered body containing no Cu or iron group metals was 0.15 mm, and that of the commercially available CBN.
The sintered body bonded with a metal mainly composed of was 0.25 mm. [Example 2] The binder powder shown in Table 1 was prepared.

[Table] TiNx powders with different nitrogen contents are produced by nitriding fine powder of titanium metal by heating it in a pure nitrogen stream.
It was created by controlling the amount of bound nitrogen by changing the heating temperature. The binder powder having the composition shown in Table 1 was heat treated in the same manner as in Example 1 and ground to a particle size of 0.4 to 0.7 μm.
This binder powder and CBN powder having an average particle size of 3 μm were mixed to prepare a mixed powder having the composition shown in Table 2. In the same manner as in Example 1, a Mo container was coated with a mixed powder containing 50% CBN by volume and the balance containing Ti(CN), HfN, and Al in a ratio of 5:3:2 by weight.
A cemented carbide with a composition of 6% Co is placed, and the finished powder is placed on top of it.
Cemented carbide with 8Cu−2Ni alloy deposited in various thicknesses was placed, Mo plugged, and an ultra-high pressure and high temperature device was used.
50kb1280°C for 20 minutes. Table 2 also shows the hardness measurement results. In addition, these sintered bodies are CBN
It was firmly bonded to the cemented carbide base material through an intermediate bonding layer containing . In addition, in the obtained sintered body
The CBN particle size was about 4 to 8 μm, and the particle size of most of the particles in the binder phase was 1 μm or less.

[Example 3]

A binder powder having a particle size of 0.5 to 0.8 μm was prepared with the composition shown in Table 3, and heat-treated. These binder powders and CBN powder with an average particle size of 3μ are each added by volume.
They were blended and mixed so that the proportions were 13% and 87%. Next, in the same manner as in Example 1, a container made of Mo was filled with the above-mentioned finished powder, a copper foil with a thickness of 5μ coated with Co was placed on top of it, and a WC-10% Co cemented carbide was placed. The container was sealed and the entire container was placed in an ultra-high pressure device and sintered. When the Cu content of the sintered body was examined using an x-ray microanalyzer, the total content of Cu and Co in the binder was approximately 7% by weight. Further, the formation of boride was investigated by x-ray diffraction, but no boride formation was observed. Furthermore, as a result of measuring the hardness of these sintered bodies, all of them had a Bitkers hardness.
It was over 4000. Furthermore, the CBN particle diameters in the obtained sintered bodies were all approximately 3 μm, and the bonded particle diameters in the binder phase were mostly 1 μm or less.

[Example 4]

A mixed powder consisting of 92% by volume CBN particles with an average particle size of 2μ and binder powder was prepared. The binder powder is a mixture of TiN _0.65 powder, Al powder, Cu powder, and Co powder in weight ratios of 70%, 26%, 3%, and 1%, respectively, and is heated in a vacuum furnace at 1000°C for 30 minutes, then pulverized. It was made into a fine powder with an average particle size of 0.5μ.
This finished powder was sintered in the same manner as in Example 1. When the sintered body was taken out and examined by x-ray diffraction, a small amount of boride was observed, but no metals such as Cu and Ni were observed. A cutting chip was created using this sintered body, and Inconel 718 was cut at a cutting speed of 100.
Wet cutting was performed at m/min, depth of cut of 0.2 mm, and feed rate of 0.05 mm/rev. For comparison, commercially available volume% is approximately 90%.
A chip made of a sintered body of CBN bonded with a metal mainly composed of Co was tested under the same conditions. When we observed the wear of the chip after cutting, we found that the maximum wear width of the flank face of the sintered body of the present invention was 0.25 mm;
The commercially available sintered body bonded with a metal mainly composed of CBN was 0.45 mm. In addition, the CBN particle size in the obtained sintered body was approximately
2μ, and the bonded particle diameter in the binder phase was 0.8μ or less. [Example 5] Wurtzite-type boron nitride powder synthesized by the shock wave method with a particle size of 1 μ or less was used, and the binder powder used in Example 4 was mixed with 85% by volume of wurtzite-type boron nitride powder and binder powder. It was mixed in a proportion of 15% by volume. Mo
This powder was filled in a container made of aluminum with the same configuration as in Example 1, and then sintered using an ultra-high pressure and high temperature device.
The hardness of the sintered body was 4800 on the Pickers scale. Further, the particle size of the wurtzite boron nitride in the obtained sintered body was about 1.5 μm, and the bonded particle size in the binder phase was 0.7 μm or less. [Example 6] 90% by weight of TiN _{0.85 and} 10% by weight of Si were mixed, heated in a vacuum furnace at 1051°C for 1 hour, and then ground to produce a fine powder with an average particle size of 0.3μ. 50% by volume of this powder and CBN powder having an average particle size of 2 μm were mixed and used as an intermediate bonding layer, and coated in the same manner as in Example 1. In addition, 10% by volume of the fine powder and an average particle size of 2μ
A sintered body was produced in the same manner as in Example 1 by mixing 90% by volume of CBN powder. When the obtained sintered body was ground and further polished using diamond paste and observed under an optical microscope, the CBN particle size was approximately 2.5μ, and most of the particles in the binder phase were 0.6μ or less. It was hot.

[Brief explanation of drawings]

FIG. 1 is a phase diagram of the Ti--N system, for explaining the characteristics of the method for manufacturing the sintered body of the present invention. FIG. 2 is for explaining the manufacturing conditions of the sintered body of the present invention, and shows the thermodynamically stable region on the pressure-temperature phase diagram of high-pressure phase type boron nitride.

Claims (1)

[Scope of Claims] 1 Containing more than 80% and less than 95% by volume of high-pressure phase boron nitride with an average particle size of 10μ or less, with the remainder being carbides and nitrides of Ti, Zr, and Hf in Group 4a of the Periodic Table. , one type or mixture of carbonitrides or a mutual solid solution compound, and a binder phase consisting of Al, Cu, and an iron group metal,
The content of Al in the binder phase is 5 to 30% by weight, the content of Cu and iron group metal elements is 1 to 20% by weight, the ratio of Cu to iron group metal elements is 1/2 to 5, and the bonding phase is The sintered body consists of fine particles, most of which are 1μ or less, with a high-pressure phase boron nitride content of 30% by volume.
If the remaining bonded phase exceeds 70% by volume, the remaining bonded phase is
4a group Ti, Zr, Hf carbide, nitride, carbonitride or a mixture thereof or a mutual solid solution compound and 0.1% by weight of Al or Si in this binder phase
Through an intermediate bonding layer containing not less than 30% by weight,
A high-hardness sintered body for tools bonded to a cemented carbide base material. 2. The binder phase of the sintered body is made of a compound of TiN, ZrN and Al, and the content of Al in the binder phase is 5 to 5.
30%, and most of the binder particles in the binder phase are
Consisting of fine particles of 1μ or less, further containing 1 to 20% by weight of Cu and iron group metal elements in the binder phase,
The high hardness sintered body for tools according to claim 1, wherein the ratio of Cu to iron group metal elements is 1/2 to 5. 3. The high-hardness sintered body for a tool according to claim 1, wherein the high-pressure phase type boron nitride is cubic boron nitride. 4 The content of high-pressure phase boron nitride exceeds 30% by volume.
Less than 70% by volume, the remaining binder is one of carbides, nitrides, and carbonitrides of Ti, Zr, and Hf from Group 4a of the periodic table.
species or a mixture thereof or a mutual solid solution compound, and 0.1% by weight or more of Al or Si in this binder.
A powder as an intermediate bonding layer containing 30% by weight or less is pressed and molded, or placed in powder form on a cemented carbide base material, or coated on the cemented carbide base material in advance, Furthermore, on top of that powder, the average particle size
High-pressure phase type boron nitride powder of 10μ or less and periodic table 4a
When carbides, nitrides, and carbonitrides of group transition metals are respectively expressed as MCx, MNx, and M(CN)x,
A compound powder with an x value of 0.5 to 0.95 and Al or an alloy or compound powder containing Al are combined by weight of Al in the binder to 5
~30% mixed, pulverized so that most of the binder particles are less than 1μ, then placed in powder form or molded by molding, and then compressed using an ultra-high pressure and high temperature device.
20kb or more, from the outside of the sintered body at a temperature of 900℃ or more.
Cu and iron group metals or alloys or compounds containing them are hardened so that the weight of Cu and iron group metals in the binder is 1 to 20%, and the ratio of Cu to iron group metal elements is 1/2 to 5. The content of high-pressure phase type boron nitride is 80% by volume in the sintered body, which is characterized by being infiltrated into the layer and sintered, as well as bonding the hard layer, intermediate bonding layer, and base material. Over 95%
A method for manufacturing a high-hardness sintered body for tools as follows. 5. The method for producing a high-hardness sintered body for tools according to claim 4, wherein the nitride of Group 4a of the periodic table is TiNx or ZrNx. 6 Claim 4, characterized in that cubic boron nitride is used as the high-pressure phase boron nitride powder.
A method for manufacturing a high-hardness sintered body for tools as described in . 7 The content of high-pressure phase boron nitride exceeds 30% by volume.
Less than 70% by volume, the remaining binder is one of carbides, nitrides, and carbonitrides of Ti, Zr, and Hf from Group 4a of the periodic table.
species or a mixture thereof or a mutual solid solution compound, and 0.1% by weight or more of Al or Si in this binder.
A powder as an intermediate bonding layer containing 30% by weight or less is pressed and molded, or placed in powder form on a cemented carbide base material, or coated on the cemented carbide base material in advance, Furthermore, on the powder, the average particle size is
High-pressure phase type boron nitride powder of 10 μ or less and periodic table No. 4a
When carbides, nitrides, and carbonitrides of group transition metals are respectively expressed as MCx, MNx, and M(CN)x,
Compound powder with an x value of 0.5 or more and 0.95 or less and Al or
The weight of Al in the binder is 5 to 30 when alloys containing Al are used.
% and Cu and iron group metals, or alloys containing them, or compound powders are mixed in such a way that the weight of Cu and iron group metals in the binder is 1 to 20%, and the ratio of Cu to iron group metals is 1/2 to 5. , most of the binder particles are 1μ
After pulverizing the powder to the following size and placing it in a powder form or molding, the hard layer is sintered using an ultra-high pressure device at a pressure of 20 kb or more and a temperature of 900°C or more. A high-hardness sintered body for tools, characterized in that the content of high-pressure phase boron nitride is more than 80% and less than 95% by volume in the sintered body, which is characterized by bonding an intermediate bonding layer and a base material. Production method. 8 The above nitride of Group 4a of the periodic table is TiNx,
8. The method for producing a high-hardness sintered body for a tool according to claim 7, wherein ZrNx is used. 9. The method for manufacturing a high-hardness sintered body for tools according to claim 7, characterized in that cubic boron nitride powder is used as the high-pressure phase boron nitride powder.