JPS62260005A - High-hardness sintered body for tool and its production - Google Patents

Abstract

PURPOSE:To produce a high-hardness sintered body for tools having excellent heat resistance by imposing powder of an intermediate joint phase contg. high- pressure phase type BN, TiC, etc., and Al, etc. and powder of high-pressrue phase type BN, etc., on a sintering hard alloy base material and sintering the same, together with Cu, etc., under a high pressure. CONSTITUTION:The powder as the intermediate joint layer contg. <70vol% high-pressure phase type BN and the balance essentially consisting of the carbide, nitride, carbonitride, etc., of Ti, Zr, Hf, etc., and further contg. >=0.1wt% Al or Si is imposed on the sintered hard alloy base material. 80-95vol% High- pressure phase type BN having <=10mu average grain size, and compd. powder of MCx, MNx, M(C, N)x (M; Ti, Zr, Hf, x; 0.5-0.95) as the bond phase of the balance and 5-30wt% Al are mixed and the mixture composed thereof is imposed on said powder. Further, 1-20wt% Cu and ferrous metal are added thereto from the outside at 0.5-5 ratio between the same and the powders are sintered under >=20kb pressure at >=900 deg.C by using an extra-high-pressure and high-temp. device. The sintered body jointed with the hard layer infiltered with Cu, etc., and the intermediate joint layer to the base material is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Cubic boron nitride (Cubic BN, hereinafter abbreviated as CBN) is a substance with the second highest hardness next to diamond, and is synthesized under ultra-high pressure and high temperature. Currently, CBS is already used as abrasive grains for grinding, and for cutting purposes, CBS is used as gold 77 and G
Sintered bodies bonded with o etc. are used in some parts. When this sintered body of CBS bonded with metal is used as a cutting tool, there are disadvantages such as a decrease in wear resistance due to the softening of the bonded metal phase at high temperatures, and damage to the tool because the work material metal is easily welded. There is. The present invention is not a sintered body bonded with such metals, but a new carbon material suitable for tool applications such as cutting tools that uses a hard gold mud compound as a binder phase that has high strength and excellent heat resistance.
This relates to a BS sintered body.

As mentioned above, CBN is a material that has high hardness and excellent heat resistance and wear resistance. Various attempts have been made to sinter only this CBN.
As described in No. 48, approximately 70 kb or more, 190
It is necessary to sinter at ultra-high pressure and high temperature above 0°C. 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 CBS has high hardness, it has poor toughness when used as a tool.

The inventors used CBN as a binder mainly consisting of carbides, nitrides, and carbonitrides of the 4a-transient polymetal of the periodic table and a compound containing Al, and containing Cu and iron group metal elements. By using these materials and finding more appropriate manufacturing conditions, we were able to obtain a highly hard sintered body with a CBN content of more than 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 when CBS was used were obtained.

A sintered body using CBN as a hard wear-resistant component will be described in detail below, 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 allows us to take full advantage of the characteristics of CBN and, for example,
It can be applied to tool materials for cutting highly hard materials such as CC cemented carbide, and cotton 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. For this reason, it is possible to improve these drawbacks by adding a suitable binder to the CBS.

One of the known methods is to use a metal binder,
An example is a commercially available sintered body in which CBN is bonded with metal Co or the like. In addition, CBN may be added with a compound other than metal, such as Alz.
Attempts have also been made to mix Ch, B, C, etc. and sinter the mixture. The former method is a liquid phase sintering under high pressure, in which sintering is carried out at a temperature at which a metal binder such as CO melts.

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 were bonded continuously in a sintered Mi fiber. He invented a sintered body for high-hardness tools containing 4θ to 80% by volume of CBN, which forms a phase, and has filed a patent application (Japanese Patent Laid-Open No. 1986-7
7811).

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 required compared to sintering only CBN. eased.

The inventors conducted a study on a product with a further increased content of CBH. If the CBH content exceeds 80% by volume, even if the CBN and the compound powder of metals from Groups 4a, 5a, and 6a of the periodic table are sufficiently uniformly mixed and sintered under ultra-high pressure and high temperature, high A strong sintered body was not 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 large, the sinterability deteriorates 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 carbides, nitrides, and carbonitrides from group 43 of the periodic table were used as binders.
In particular, when the transition metal of group 4a is represented by M, M Cx
, M N x, M (C, N) x When a mixed powder containing Al, Cu, and iron group metal is used for a powder in which the value of X of x is below a certain value, the composition has a CBN content of over 80% It has been found that a high-strength sintered body can be obtained even if

Carbides, nitrides, and carbonitrides of Group 4a of the periodic table are the first
As represented by the phase diagram of T i N in the figure, phases having an NaCl type structure exist in a wide composition range of M C, M N, M-C, and N. When the value of X was 1 or less, that is, by using a material with a relatively high concentration of C and N atomic vacancies, sinterability was improved. Furthermore, VIit= was found that the sinterability was improved when an Al compound was added to the bonding material, compared to when only MCX, MNx, and M (C,N)x were used. Furthermore, it was found that when trace amounts of Cu, Fe, and iron group metal elements such as Nis Co were contained, the sinterability was further improved and the strength of the sintered body was also improved. MC used as a binder raw material
The preferred range of the value of X in X% MNX% M (C,N)x is 0.95 or less. In addition, Al is included in the binder.
When the f element is present in an amount of 5% or more, and Cu and iron group metals are present in a total amount of 1% or more of these metal elements in the binder, a high-strength sintered body can be obtained. The CBN content in the sintered body is 8 by volume.
5%, and the values of MCx, MNx, M (C, N) As a result, those with particularly high strength and excellent performance as tools had an X value of 0.50 to 0.95 and an AJ addition amount of 5 to 30% by weight in the binder. The total amount of iron group metals added ranged from 1 to 20% by weight in the binder.

In the sintered body of the present invention, the volume percentage of high-pressure phase boron nitride in the sintered body is more than 80% and less than 95%.

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 the sintered body as a tool is observed. Further, if the content is less than 80%, the binder phase of the sintered body becomes a continuous phase in the Mi fiber, and the hardness decreases.

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 maximum when the value of X is about 0.7. 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, the CBN crystal is difficult to deform, but the TiN
x-particles can easily undergo deformation. For the reasons mentioned above, in this case, TiNx with a low value of ) The same can be said for x. However, this alone does not provide sufficient bonding strength between CBN particles. For example, in liquid phase sintering of W C-Co cemented carbide, if hard particles are dissolved into a binder phase and reprecipitated, a product with high bonding strength between the binder phase and hard particles or between the hard particles can be obtained. .

In the sintered body of the present invention, by making an Al compound exist in the binder, this! (It was discovered that the following phenomenon occurs. MCx-MNx, , M
When an Al compound is added to (C,N)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 further lamp-finished and observed, no CBN particles are observed to fall off when the amount of added A2N in the binder is 5% or more by weight. However, when observing the fracture surface of the sintered body, C
Although most of the BN grains had intragranular fracture, some areas with intergranular fracture were also observed. A sintered body was prepared by adding Cu and a trace amount of iron group metal to the composition of this CBN sintered body, and when its fracture surface was observed, no grain boundary fracture was observed. The reason for this is assumed to be as follows. C
u and iron group metals are MCx, MNx, M (C
,N)X reacts with the excess M of the Group 4a transition metal to generate a low melting point liquid phase, which uniformly infiltrates the interface between CBS and a binder such as MC, MN, or M(C,N). The M-Cu and M-iron group metals that have penetrated into this interface include CBN and the binder phase M.
C; C because it has good affinity with MN, M (C,N)
BN-CBN or CBN-MC%MN, M (C,
It is thought that this is to increase the bonding strength of N).

In addition, the sintered body containing Cu and iron group metal is CBN.
MCSMN, M (C.

N) A large amount of polide such as M 82 is formed at the interface. 0 Normally, polide such as M B z is brittle and, if present in large amounts, causes breakage. On the other hand, in the sintered body containing Cu and iron group metals, the formation of M B z etc. is suppressed, and therefore, the sintered body containing Cu and iron group metals
It is thought that the CBN particles and the binder phase were tightly bound together.

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, but as MClMN, M (
C, N), etc., or MCx,
Since MNx and M(C,N)x react with excess M and All and exist in the form of intermetallic compounds, strength does not decrease at high temperatures. However, when the content of CII and iron group metals exceeds 20% by weight in the binder, Cu and iron group metals become MC,
Solid solution or excess M in the bonded phase of MN, M(C,N)
and Al to form intermetallic compounds,
Since it exists in the sintered body in a pure metal state, the hardness of the sintered viscous body decreases and tool performance deteriorates. Further, the ratio of Cu to iron group metal is preferably A to 5. If this ratio is less than z, the Cu content is too low and the generation of polide cannot be suppressed. On the other hand, if this ratio exceeds 5, the Cu content increases and the sintered body This is because the hardness of the material 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 less than 1 μm, and coarse particles may cause problems in the sintered body. The structure tends to become uneven. The most preferred method is Affi, in which the binders MCx, MNx, M (
In this method, excess M of C,N)x is reacted with metal Ae in advance to form an intermetallic compound of M-AJ, which is then pulverized and used. In this case, the combination RMCX, MNx
, M (C, N) In addition, M- synthesized by reacting metal M and metal L in advance
Al intermetallic compounds (e.g. Ti, Aj!3, TiA
T! , Ti2Al. , ZrAlz, ZrAl, etc.) may be used.

Another form of A/compound A I N, T i
It may be added in the form of a nitrogen-containing compound such as x Ae N% Z rz Al-N.

In addition, in the case of Cu and iron group metals, the most preferable method is to infiltrate them from the outside of the sintered body by diffusion during sintering, or add them by reacting with the binder in the same way as when adding Al. .

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 be reduced, and especially when used as a cutting tool, a finer crystal grain will provide a better machined surface.

The particle size of the binder phase, which is another vf@ of the present invention, is 1μ
It consists of the following extremely fine crystal grains. As a result, the sintered body has a high CBN content, but the binder phase is uniformly made of CBN.
A high-strength sintered body is obtained with a structure dispersed between N particles.

In manufacturing the sintered body, we use ultra-high pressure and high temperature equipment used for diamond synthesis, at a pressure of 20 kb or more and a temperature of 9.
Perform at 00°C or higher. Particularly preferable sintering pressure and temperature conditions are a pressure of 30kb to 70kb and a temperature of 1100℃ to 1500℃.
It is ℃. The upper limits of these pressure and temperature conditions are both within the range of practical operating conditions for industrial-scale ultra-high pressure and temperature equipment. 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. C to obtain sufficient bonding strength
Contains less than 70% BN by volume, with the remainder being Ti, Zr, and H.
The bonding may be performed using an intermediate bonding layer made of one type of carbide, nitride, or carbonitride of f, or a mixture thereof or a mutual solid compound. Incidentally, it is preferable that this intermediate bonding layer contains 0.1% by weight or more of 81 or Si.

This will be explained in more detail below with reference to Examples.

[Example 1] A mixed powder consisting of 90% by volume CBN particles having an average particle size of 3 μm and binder powder was prepared. The binding material is T i
80% by weight of N o, az powder and Al powder each
, 20% mixture was heated at 1000°C in a vacuum furnace.
After heating for 30 minutes, the mixture was ground into a fine powder with an average particle size of 0.3μ. When this binder powder was examined by X-ray diffraction, in addition to TiN, Ti2Aj! N, TiAj
! *, Compounds generated by the reaction of TiN and Al such as TjAl were detected, and metal A6 was not detected. This is due to the relatively excessive T with respect to the N of TiNO,ez.
It is produced by the reaction of i with the added Ae.

This mixed powder of CBN and binder has an outer diameter of 141 and an inner diameter of IQ+n+. CBN in a VIO container by volume 60
After placing a cemented carbide composite made of WC-6%C0M1 (outer diameter 101cm, height 221pu) coated with a mixed powder containing a small amount of TiN and Al by weight, the balance was 0.30g. Filled. On top of this, a cemented carbide (outer diameter IQms, height 2cm) with a thickness of 2μ and 9 Cu-INi alloy deposited was placed, a MO stopper was placed, and the entire container was placed under the ultra-high pressure used for diamond synthesis. put it in the device. Pressurize to 50 kb,
Next, the temperature was heated to 1250°C and held for 20 minutes.

The removed sintered body was polished using a diamond grindstone.
The cemented carbide on which Ni was vapor-deposited 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 was firmly bonded to the cemented carbide via the CBS-containing bonding layer. The hardness was measured using a Pinkers hardness tester under a load of 5 kg and showed a value of about 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.
%Met. Furthermore, the products of this sintered body were investigated by X-ray diffraction, and the results showed that CB N , T i N , A I N
However, very few polides such as 'l'iBz were detected. Incidentally, a sintered body containing no Cu and iron group metals was produced in the same manner and the product was examined by X-ray diffraction, but it was found that in addition to CBN, TiN, and ANN, a large amount of T i B 2 was present in the product. Was. Chips for cutting were created using these two types of sintered bodies.

The work material is WC-1 with a Vickers hardness of approximately 1200.
A punch for plastic working made of 5% CO cemented carbide was selected, cutting speed 18 m/min, depth of cut 0.2 m, feed 0.1 mm/min.
Cutting was performed by rotating for 20 minutes. For comparison, commercially available volume% is approximately 9
When the wear of a thousand knobs made of a sintered body bonded with a metal containing 0% CBN and mainly composed of Co was observed, the maximum wear width of the flank surface of the sintered body of the present invention was 0.10 m1. On the other hand, that of the sintered body containing no Cu or iron group metal was 0°151mm, and that of the sintered body bonded with a commercially available metal mainly composed of CBN was 0.25mm.

[Example 2] The binder powder shown in Table 1 was prepared.

The fine powder was heated in a pure nitrogen stream to nitride it, and the amount of bound nitrogen was controlled by changing the heating temperature.

The binder powder having the composition shown in Table 1 was heat treated and pulverized in the same manner as in Example 1. This combined powder and average particle size 3
A mixed powder having the composition shown in Table 2 was prepared by mixing with μ CBN powder.

In the same manner as in Example 1, 5 volumes of CBN were added to an MO container.
0%, the remainder is Ti (C,N), HfN and Af
WC- coated with powder (containing 5:2 to 3:2 by weight)
A cemented carbide with a composition of 6% CO is placed, and the finished powder and 8 C are placed on top of it.
A cemented carbide coated with u-2Ni alloy of various film thicknesses was placed, a Mo plug was placed, and a 50 kb film was formed using a remote high pressure and high temperature device.
It was held at 1280°C for 20 minutes. Table 2 also shows the hardness measurement results. Further, these sintered bodies were firmly bonded to the cemented carbide base material via an intermediate bonding layer containing CBN.

Comparing the sintered bodies of Table 2 A, B, and C, the hardness decreases when the Cu-Ni content becomes 22%. Next, looking at the CBN content, as the CBN content increases, the hardness increases, but when it becomes too high (97%), the cirrhosis decreases to 3000. In this case, the binder content in the sintered body is insufficient, and a completely dense sintered body cannot be obtained under such pressure and temperature conditions. Next, comparing G and H1■ which have different Ap contents in the binder, the higher the Ap content, the higher the hardness.

[Example 3] A binder powder having the composition shown in Table 3 was prepared and subjected to heat treatment. These binder powders and CBN powder having an average particle size of 3 μm were blended and mixed in a volume of 13% and 87%, respectively. Next, in the same manner as in Example 1, a container made of MO was filled with the above-mentioned complete material, a copper foil with a thickness of 5 μm 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 about 7% by weight. Further, the formation of polide was investigated by X-ray diffraction, but no formation of polide was observed. Furthermore, as a result of measuring the hardness of these sintered bodies, they all had a Vickers hardness of 4000 or more.

Table 3 [Example 4] A mixed powder consisting of 92% by volume CBN particles with an average particle size of 2 μm and binder powder was prepared. The binder powder is Ti
After heating a mixture of N o, as silk powder, Al powder, Cu powder, and CO powder in weight ratios of 70%, 26%, 3%, and 1%, respectively, at 1000°C for 30 minutes in a vacuum furnace,
Grind to an average particle size of 0.5. It is made into a fine powder of u. 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 polide was observed, but no Cu%Ni metal was observed. A cutting tip was made using this sintered body, and Inconel 718 was cut at a cutting speed of 100 m/min.
Wet cutting was performed with a depth of cut of 0.2 mm and a feed rate of 0.05 mm/rev.

For comparison, a test was conducted under the same conditions using a chip made of a commercially available sintered body in which approximately 90% CBN by volume was bonded with a metal containing CO as a main component. When the wear of the tip after cutting was observed, 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 had a richness of 0.45 liters.

[Example 5] Wurtzite type boron nitride powder synthesized by the shock wave method with a particle size of 1 μm or less was used, and the binder powder used in Example 4 was mixed with wurtzite type boron nitride powder at 85% by volume and binder powder at 15% by volume.
They were mixed in a proportion of % by volume.

This powder was filled into an MO container with the same configuration as in Example 1, and then sintered using an ultra-high pressure, high A device. The hardness of the sintered body was 4800 on Vickers hardness.

[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 shows the thermodynamically stable region on the pressure-temperature phase diagram of high-pressure phase type boron nitride using dust for explaining the manufacturing conditions of the sintered body of the present invention. Patent Applicant: Sumitomo Electric Industries, Ltd. Agent: Kama 1) Text 2 Figure 1 T or 10 Figure 2 Temperature (0C)

Claims (9)

[Claims] (1) Containing more than 80% and less than 95% by volume of high-pressure phase type boron nitride with an average particle size of 10 μ or less, the remaining binder phase being carbides and nitrides of Ti, Zr, and Hf from Group 4a of the periodic table, It is composed of one kind or a mixture of carbonitrides or a mutual solid solution compound and a compound of Al, the content of Al in the binder phase is 5 to 30% by weight, and the majority of the binder particles of the binder are 1 μm in size. It consists of the following fine particles, and furthermore, in the binder phase, C
A sintered body containing 1 to 20% by weight of u and iron group metal elements, and a ratio of 1/2 to 5 of the two, and a sintered body containing less than 70 volume% of high-pressure phase boron nitride, with the balance being a material from the periodic table. Ti of group 4a,
Thickness 2 consisting mainly of Zr, Hf carbide, nitride, carbonitride or a mixture thereof or mutual solid solution and containing 0.1% by weight or more of Al or Si
A high-hardness sintered body for tools bonded to a cemented carbide base material through an intermediate bonding layer of less than mm. (2) The binder phase is made of a compound of TiN, ZrN, and Al, the content of Al in the binder phase is 5 to 30% by weight, and most of the binder particles of the binder are fine particles of 1 μ or less. Claim (1) is characterized in that the bonding phase contains Cu and iron group metal elements in an amount of 1 to 20% by weight, and a ratio of 1/2 to 5 of the two. High hardness sintered body for tools. (3) The high-hardness sintered body for tools 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 on the cemented carbide base material is 7.
Less than 0% by volume, the remainder being Ti, Zr from Group 4a of the periodic table,
Embossing powder as an intermediate bonding layer containing one type of Hf carbide, nitride, carbonitride, or a mixture or mutual solid solution of these, and 0.1% by weight or more of Al or Si. It is molded or placed in powder form, or it is coated on the cemented carbide base material in advance, and then on top of the powder is a high-pressure phase type boron nitride powder with an average particle size of 10μ or less and the periodic table. MCx, MNx, M(C, N
) When expressed as x, a compound powder with a value of x of 0.5 to 0.95 and Al or an alloy or compound powder containing Al are mixed in an amount of 5 to 30% by weight of Al in the binder, and this is powder After the sintered body is molded or pressed and placed, an ultra-high pressure and high temperature device is used to increase the pressure to 20 kb or higher and the temperature to 900°C or higher to inject Cu and iron group metals, or alloys or compounds containing these as a binder from the outside of the sintered body. The Cu and iron group metals in the hard layer are infiltrated into the hard layer so that the weight thereof is 1 to 20%, and the ratio of both is 1/2 to 5. The content of high-pressure phase type boron nitride, which is characterized by bonding, exceeds 80% by volume in the sintered body95
% or less and a method for producing the same. (5) Nitride of Group 4a of the periodic table is TiNx, ZrNx
A method for manufacturing a high-hardness sintered body for tools according to claim (4). (6) A method for manufacturing a high-hardness sintered body for tools according to claim (4), characterized in that cubic boron nitride is used as the high-pressure phase boron nitride powder. (7) The content of high-pressure phase boron nitride on the cemented carbide base material is 7
Less than 0% by volume, the remainder being Ti, Zr from Group 4a of the periodic table,
A powder as an intermediate bonding layer containing 0.1% by weight or more of Al or Si, which is mainly composed of Hf carbide, nitride, carbonitride, or a mixture thereof, or a mutual solid solution, is molded. It is pressed and molded, or it is placed in powder form, or it is coated on the cemented carbide base material in advance, and then on the powder, high-pressure phase type boron nitride powder with an average particle size of 10 μ or less and the powder shown in the periodic table are added. Group 4a transition metal carbides, nitrides, and carbonitrides are MCx, MNx, and M(C,N)x, respectively.
When expressed as, a compound powder with an x value of 0.5 to 0.95, Al or an alloy containing Al, and 5 to 30% by weight of Al in the binder, and Cu and iron group metals or alloys containing these. ,
Alternatively, compound powder is mixed with 1 to 20% by weight of Cu and iron group metal in the binder, the ratio of both is 1/2 to 5, and this is placed in a powder form or molded by molding, and then placed in an ultra-high pressure device. The hard layer is sintered at a pressure of 20 kb or more and a temperature of 900° C. or more using a high-pressure phase type boron nitride content that is characterized by bonding the ultra-hard layer, intermediate bonding layer, and base material. A method for producing a high-hardness sintered body for tools whose volume in the body is more than 80% and less than 95%. (8) The nitrides of Group 4a of the periodic table are TiNx, Zr
A method for manufacturing a high-hardness sintered body for a tool according to claim (7), characterized in that the material is Nx. (9) A high-hardness sintered body for tools and a method for manufacturing the same according to claim (7), characterized in that a cubic boron nitride powder is used as the high-pressure phase boron nitride powder.