JPS6286102A - Manufacturing method of composite sintered body for tools - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a composite tool having excellent adhesive strength.

Diamond is the hardest substance, and single-crystal diamond has been used to cut nonferrous metal materials and the like for a long time. In recent years, diamond sintered bodies in which fine diamond particles are bonded with Co-based metal using ultra-high-pressure sintering technology have become commercially available, and these are more resistant to impact than single-crystal diamond, making them suitable for use in diamond tools. It is attracting attention as a way to expand its range. In this metal-bonded diamond sintered body, the thickness of the diamond layer is approximately 0. JR-, and is directly joined to the WC-Co cemented carbide motherboard (O).The manufacturing method for this product is described in Tokukosho!; 2-/2/2 Publication No. O, but WC-Co cemented carbide is
Diamond powder is placed in contact with a mixed powder of -Co cemented carbide or a WC-Co cemented carbide obtained by pre-sintering this, and this is heated under high pressure using an ultra-high pressure device to form the base material. WC-Co mixed powder or WC-C! The CO in the o alloy is melted, and the molten Co component moves into the diamond powder layer and becomes a bonding material for diamond.

In this case, the pressurization and heating conditions are such that diamond is thermodynamically stable, and the molten Co has a solvent action that can dissolve and reprecipitate diamond, and serves as a binding material for the diamond sintered body and as a matrix. Serves as a bonding material for cemented carbide. In the sintered body thus obtained, adjacent diamond particles are directly bonded to each other, and since the cemented carbide base material and the diamond sintered body layer are made of the same bonding metal, a strong bond is achieved. It is said that

When using this commercially available diamond sintered body as a machining tool, a diamond-containing hard layer is provided only on the part that will become the cutting edge, and this is bonded to a highly rigid base material to create a composite tool, which increases the strength of the tool. This is a good way to increase it.

In recent years, TiC and TiN have been used as an example of such composite tools.
Cutting tools coated with a base cemented carbide matrix are commonly used. Although WCC cemented carbide itself is widely used as a cutting tool, it has high rigidity, excellent toughness, and good thermal conductivity, and is particularly suitable as a base material for the above-mentioned composite tools.

However, these composite tools have the following deficiencies.

When making a commercially available diamond sintered body using gold flco as a binding material into a cutting tool for Isoki processing, the tooling tool is created by brazing the cemented carbide base material to which the diamond sintered material layer is bonded and the steel Piton yank. .

Cemented carbide and Yuno's wax (The silver brazing material used for each Yuzu
Su, no de] (1! Odate six ha te (lotus me, t L size 1rF 1 size - stirrup Ni 750~1000C
It is. If the diamond sintered body is brazed at this temperature, the diamond layer may peel off from the interface with the base cemented carbide.

Even if it does not peel off after seven brazing cycles, it will peel off after repeated heating several times. Furthermore, in order to confirm this, the diamond-fired viscous body directly bonded to the cemented carbide base material was heated and held at foooC for 30 minutes under a vacuum of /'OmWLHg using a vacuum furnace. Of the two samples taken out of the furnace, in seven of them the interface between the diamond sintered body layer and the cemented carbide base material had completely separated, and in the other seven, cracks had formed at the interface, and when force was applied, easily dismantled.

In this case, the actual peeling surface was the interface between the diamond sintered body layer and the cemented carbide base material, and it is thought that the adhesive strength at this interface was reduced by heating. Figure 1 is a microscopic photograph (i
soo times). The black continuous diamond sintered body layer has a structure in which diamond particles are bonded to each other, and the white parts in the gaps are metal CO, which is the bonding metal of the diamond sintered body, and at the interface with the gray base material. is CO
There is a layer enriched with Co, and the diamond particles are bonded to the WC-Co cemented carbide via Co.

According to the research conducted by the present inventors, diamond particles look like diamond (melting diamond), and diamond grows under thermodynamically stable conditions using catalyst-solvent metals such as iron group metals. When a pre-sintered diamond sintered body is reheated under normal pressure, its strength decreases at a relatively low temperature. This is presumed to be because the iron group metal present in contact with the diamond particles has a catalytic effect that promotes the reverse transformation of diamond into graphite. In a sintered body in which direct bonding between diamond particles has developed in the diamond sintered body layer, the substantial contact interface of the iron group metal, which is the diamond bonding metal, is reduced, and when the sintered body is reheated, Strength reduction is reduced. However, in the above-mentioned commercially available sintered bodies, the diamond sintered body layer has a well-developed bond between the particles, but the interface with the cemented carbide matrix serves as a bonding surface between the diamond particles and CO as described above. There is. Therefore, if this is heated, the strength of the interface with the base material will be significantly reduced, and it is expected that deterioration will progress. This is a serious defect of this composite sintered body. One possible way to prevent such a decrease in the strength of the joint interface is to lower the heating temperature by changing the brazing material used for brazing when making the tool to one with a lower melting point. However, with a tool bit made using low-temperature brazing material, when the cutting edge temperature of the tooling tool increases during cutting, the brazing material softens and the brazing part may come off, limiting its range of use.

The present inventors have investigated various methods for obtaining a composite diamond sintered body whose bonding strength with the cemented carbide base material does not deteriorate significantly even after reheating. For example, a diamond sintered body layer contains an iron group metal as a solvent for diamond in order to create a direct bond between diamond particles, and an intermediate layer of Cu that does not dissolve diamond at the interface with the cemented carbide base material. I tried making a sintered body with this. In this composite sintered body, even when heated to 7000°C in vacuum, the diamond sintered body layer and the base cemented carbide did not separate.

When a composite sintered body having such an intermediate layer with low high-temperature strength at the interface with the cemented carbide base material is used as a cutting tool, the intermediate layer will break due to the stress and heat applied to the diamond sintered body layer that will become the cutting edge. The disadvantage is that the layer is plastically deformed and the cutting edge is damaged.

The inventors of the present invention have conducted further studies in order to eliminate such drawbacks. For the reasons described above, the diamond sintered body layer and the cemented carbide containing CO, which is a solvent metal for diamond, are not directly bonded, but it is sufficient that a substance that is difficult to deform at high temperatures exists at this bonding interface. Furthermore, the characteristics required of this intermediate bonding layer are that it can firmly bond diamond and the base material cemented carbide during sintering under ultra-high pressure, and that it can be heated to prevent excessive residual stress from occurring in the sintered body. It is necessary that the expansion coefficient substantially match that of the diamond sintered body and the base cemented carbide. Furthermore, when used as a cutting tool, it is desirable to have good thermal conductivity in order to dissipate the heat generated at the cutting edge, and from the viewpoint of strength, it is not possible to use a tool that is too brittle.

From the above point of view, as a result of examining various types of (orF), cubic crystal 8-bodi + III table (C1 lower CBN ngo-o), L-
1,1j110■? 11 pa Al1a,! It was concluded that carbides, nitrides, and carbonitrides of the FRA group are suitable.

The intermediate bonding layer in the present invention is composed of CBN and cermet, and has high rigidity, excellent high-temperature strength, and also good thermal conductivity.

According to experiments conducted by the present inventors, the diamond sintered body and the cemented carbide base material were firmly bonded via this intermediate bonding layer under the ultra-high pressure and high temperature conditions for manufacturing the diamond sintered body. These composite sintered bodies having an intermediate bonding layer consisting of CBN, carbide, and nitride have diamond solvent metals such as Co flowing out from the cemented carbide base material etc. at the interface between the diamond sintered body layer and the intermediate bonding layer. Not present in large quantities, diamond particles and medium IFji +:! The area where the laminae are in direct contact is the dog.

Therefore, there is no decrease in strength due to reheating. As described above, according to the present invention, the diamond sintered layer can be firmly attached to the super-alloy base material, which is very useful.
The reason for such a strong bond is presumed to be as follows.

First, regarding the relationship between the intermediate bonding layer and the super(1) alloy, we will discuss
,,! ; Group A carbides and nitrides form a mutual solid solution with WC, which is the main component of the cemented carbide matrix, and furthermore, carbon in the intermediate layer.
Since BN reacts with WC-Co, which is the cemented carbide base material, to produce polide, it is thought that the two adhere firmly.

Next, regarding the adhesion between the intermediate bonding layer and the diamond sintered body, diamond powder and iron group metals, carbides, and nitrides, which are usually used as a bonding phase for diamond, are also included in the intermediate bonding layer as shown in 'Aa' of the periodic table! It has excellent affinity with group A carbides and nitrides, and furthermore, since the intermediate bonding layer and the diamond sintered body layer are in contact with each other in a powder state before sintering, after sintering,
It is thought that there is a layer in which the intermediate bonding layer and the diamond sintered body layer are mixed, resulting in strong bonding.

In addition, carbides and nitrides of groups 4a and 5a of the periodic table have 0.
By adding 7 to 50% by weight of Al or Si, the sinterability of the intermediate bonding layer itself is improved, and the affinity between these carbides and nitrides and diamond particles is also improved.

In particular, when TiN, which is a nitride of Groups 4a and 5a of the periodic table, contains Al in an amount of θ/~jO, the effect is excellent.

If the content of AI or/and Sl is less than 0.7% by weight, the addition has no effect, and if the content exceeds 50% by weight, the amount of AI or/and Si in the intermediate bonding layer is too large and the strength of the intermediate layer is reduced. decreases.

This type of intermediate bonding layer may be applied on the cemented carbide base material in the form of a slurry of powder blended with the composition of the intermediate bonding layer, or it may be left in powder form or pre-embossed. As such, it is possible to place this on cemented carbide. This is an advantageous method for forming a thin intermediate layer when coating, or a thick intermediate layer when using an embossing body.

Since the intermediate bonding layer according to the present invention contains CBN, it has high thermal conductivity, high high-temperature strength, and can have a coefficient of thermal expansion comparable to that of a diamond sintered body. CBN
If the content exceeds 70% by weight, the remaining periodic table 4a
, the amount of group 5a carbides and nitrides is less than 30% by weight, and these carbides and nitrides and W, which is the main component of the cemented carbide base material.
The amount of mutual solid solution formed with C decreases, and the polide produced by the reaction between OBN and WC-Co in the intermediate bonding layer is brittle, resulting in a decrease in the adhesive strength between the intermediate bonding layer and the cemented carbide base material. Tend. Moreover, if the content of OBN is less than 5% by weight, the effect of containing CBN will be lost.

Therefore, the content of CBN in the intermediate bonding layer is preferably 5 to 70% by weight.

The thickness of the diamond-containing hard layer of the composite sintered body according to the present invention varies depending on the purpose of use, but generally Q, j; a
A range of 2 degrees from m is suitable. When used as a tool cutting edge for cutting, the flank surface of the tool cutting edge is usually less than about 0.5 nL- during wear when the tool is at its last due to wear, so the thickness should be larger than that, that is, Q, j. ; It is sufficient to have a diamond-containing hard layer with a thickness of at least 2 am, and a thickness exceeding 2 am is not actually necessary.

The thickness of the intermediate bonding layer made of CBN, carbide, and nitride, which is a feature of the present invention, is preferably σ0/˜°2 mm. If the thickness of the intermediate bonding layer is less than 0.001 m, there is no effect of using the intermediate bonding layer, and if the thickness exceeds 2 mm, it is necessary to use cemented carbide as the base material to be bonded using the intermediate bonding layer.

In particular, WCC cemented carbide base material has high rigidity and excellent thermal conductivity, and since it contains a metal binder, it also has excellent toughness, making it suitable as a base material.

The structure of the composite sintered body for tools according to the present invention is shown in FIG.

Reference numeral 1 is a diamond-containing hard sintered body layer used as a cutting edge of a tool, and reference numeral 2 is an intermediate bonding layer in which the base material WCC cemented carbide 3 is made of carbide or nitride, which is a feature of the present invention.

Examples of carbides and nitrides in the intermediate bonding layer of the present invention include carbides such as TiC, ZrC, HfC, NbC, and TaO, and TiN+ZrN+HfN+Nb.
N! Nitride such as TaN.

Or a mixture of these or Ti (C,N), Zr (
Carbonitrides such as 0, N) are used.

The method for producing a composite sintered body according to the present invention involves adding a necessary amount of carbide or nitride powder between the cemented carbide base material and the diamond-containing hard layer forming powder in powder form or as a stamped body; A powder layer that forms an intermediate bonding layer is created by applying a powder made into a slurry by adding an appropriate solvent to a hard alloy base material, and then hot pressing this under ultra-high pressure and high temperature to create a diamond-containing hard layer. It is also possible to adopt a method in which an intermediate bonding layer made of carbide or nitride is simultaneously sintered and bonded to the base material at the same time.

Periodic table number '+a+5a in the intermediate bonding layer used in the present invention
Group metal carbides and nitrides are high-strength compounds, but under ultra-high pressure conditions (typically 20 kb - 90 kb) during sintering of diamond-containing layers, these compounds cannot be pressurized at pressures close to the ideal shear strength of these compounds. These compound powder particles are deformed, crushed, easily packed into a dense state, and then heated to form a dense sintered body.

Carbide of group 5a of the periodic table that forms the intermediate bonding layer.

When metal is M in nitride or carbonitride powder, it becomes MC.

MNX is represented by M(NIC)/Y and can exist in a wide range of values of X outside of the stoichiometric composition (x-/).

In the present invention, a strong bond is achieved particularly when a non-chemical chemical compound having an X value of 0.9f or less, preferably in the range of 0.9 to 0.5 is used. The reason for this is that it is easy to sinter even at low temperatures due to the presence of atomic pores, and when it contains CBN, it reacts with CEN to form a strong bond, and also reacts with the diamond particles in the hard layer and the WC in the base material, resulting in both This seems to be due to the strong bond between the two. In addition, in the examples described later in this application, the values of X of these compounds were all equal to or less than o, qg. Especially 'piN7 is x
−0, f powder was used.

The diamond-containing hard layer of the present invention is diamond 20~
It contains 95% by weight, and the remainder consists of a known binder phase. When the sintered body of the present invention is used as a tool such as a cutting tool, this hard layer becomes the cutting edge of the tool. In the present invention, the composition of this hard layer can be changed depending on the application. Especially when wear resistance is important and for applications where natural diamond tools are used, 90% by volume
A sintered body made of the above diamonds can be obtained.

To obtain such a diamond sintered body, it is possible to sinter only the diamond powder, but it is also possible to mix the diamond powder with a metal powder or a metal compound powder that serves as a binder.

In addition, it is also possible to impregnate a molten diamond-forming catalyst metal or other binding metal into the diamond powder layer under ultra-high pressure and high temperature. In the aforementioned diamond sintered body directly bonded to the cemented carbide base material currently on the market, CO, which is the bonding metal contained in the cemented carbide base material, penetrates into the diamond powder layer and the bonding metal of the diamond sintered body is dissolved. becomes.

In the case of the present invention, the bonding metal can be selected regardless of the bonding metal of the base cemented carbide.

For example, as in the inventor's earlier application (Japanese Patent Application No. 5/173317), by making a diamond sintered body with a bonding metal mainly composed of Cu, conventional diamond sintered bodies can be prevented from heating deterioration. A composite sintered body having better properties than a tool can be obtained. In this sintered body, the diamond sintered body layer does not deteriorate when heated to about 7000°C, and the bonding interface with the cemented carbide base material also does not deteriorate. In addition, diamond and Periodic Table 4a, j;
, carbides and nitrides of group O-a metals.

The diamond of the present invention is a composite sintered body of boride and silicide compounds, in which these compounds form a continuous binder phase in the structure, and the hard layer has a diamond content of 20 to 10% by volume. It can be applied as a containing hard layer.

In addition, another prior application by the present inventors (Patent Application Sho!; 2-3; /3 Ryo/) improves the grindability, which was one of the drawbacks of conventional diamond sintered bodies for tools. The diamond content in the sintered body accounts for 30 to 70% by volume, and the remainder is /
, has a binder phase consisting of WC below , u and an iron group metal. This diamond-containing hard layer can also be applied to the present invention.

If the diamond content layer exceeds 95% by volume, the diamond cannot be sintered sufficiently because the binder made of carbides of groups 4a, 5a, l, and a of the periodic table and the iron group metal or the binder made of copper alloy decreases. If the diamond content is less than 20% by volume, the wear resistance of the sintered diamond decreases.

The composite sintered body of the present invention is used for various purposes such as machining tools, grindstone dressers, and drill pits. In particular, the features of the present invention are exhibited when the tool is bonded to the tool support by heating using methods such as brazing, and the bonding strength is more stable than that of conventional natural diamond tools or diamond sintered compact tools currently on the market. Obtainable.

Examples will be described below.

(Example/) - Powder made of TiN containing 523% CBN and the balance 10% AI on the top surface of a sintered body having an outer diameter/Qmm and a height of 3mm with a ~VC-B%CO composition. A slurry-like solution mixed with an organic solvent containing ethylcellulose was applied. This was placed in a Mo container with an inner diameter of QInm and an outer diameter of 2 nm, and an average particle size of 5 nm was placed on top of this. U diamond powder to C
0.3 g of the mixed powder of BN, TiN, and AI was filled in such a way that it was in direct contact with the coated surface. Furthermore, on top of this, the thickness θ
Three pieces of Fe-Ni alloy plates were placed. The container was capped with a Mo stopper and the entire container was placed in an ultra-high pressure device used for diamond synthesis. Pyroferrite was used as the pressure medium, and a graphite cylinder was used as the heater. First, the pressure was raised to Okb, and then the temperature was raised to 7300°C and held for 30 minutes. The MO tea container was taken out from the ultra-high pressure device u, and the Mo was ground off to obtain a sintered body. The obtained sintered body has an outer diameter of approximately 70
Thickness/My diamond sintered body is about 50mm thick. It was firmly bonded to the WC-%CO cemented carbide base material via an intermediate bonding layer containing u of CBN.

In addition, when this bonding interface was examined using XMA, no areas rich in Co in the cemented carbide base material or Fe or Ni used in diamond sintering were found, and diamond particles with an average particle size of 3. was strongly sintered with a Fe--Ni binder of /2% by volume.

This composite sintered body was cut using a diamond cutting wheel and brazed to a steel bite shank using a usual silver solder for cemented carbide at about 00°C. After brazing, the cutting edge was polished with a diamond grindstone and examined, but there was no abnormality in the bonding state between the diamond sintered body layer and the cemented carbide base material. Using this cutting tool, cut a WC-72% Co cemented carbide round bar with an outer diameter of JO at a speed of /! ; Cutting was performed under the conditions of m/M, depth of cut 05, and feed θ/de/rotation. Although cutting was performed for 20 minutes, the diamond sintered body layer did not peel off. While the tool flank was worn, the angle was θ15. A cutting tool was made under the same conditions using a commercially available tool sintered body in which a diamond sintered body with Co as a binder was directly bonded to a cemented carbide base material, and a round bar made of the same cemented carbide was made under the same conditions as described above. When cutting, the diamond sintered body layer peeled off from the cemented carbide base material interface during the cutting period W, making it impossible to cut.

('μm'M example average particle size 3, u CBN powder, average particle size / , u (
7) TiN powder and TIc powder with an average particle size of 1, u were mixed in a weight ratio of ≠0:37:23, respectively. This powder has an outer diameter/Qmrn.

Embossed with 7 wings in height. Outer diameter/2 stops, inner diameter/Qmm Mo
Place the WC-10% CoIq hard alloy motherboard (O) in a container made of
Place the above-mentioned embossing body on top of that, and then place the average particle size of 3 on top of that.
, u of diamond powder and TIc were filled with a mixed powder having a volume ratio of: , 2. The rest was hot pressed under ultra-high pressure in the same manner as in Example. The obtained sintered body is
The hard layer consisting of diamond and 20 volume Qk% of 1 blind c in container m96 is CBN, TiN, 'l'ic Ti
(C,N), J: ”) was firmly bonded to the cemented carbide base material through the intermediate bonding layer of the blade. The sintered body was heated to 1000°C in a vacuum furnace for 30 minutes.
ifl hold i t-ka, lt”A mount (k h-+
There was no delamination and no peeling of the bonded surfaces.

(Example 3) 33% by weight C was added to a Mo container with an outer diameter of 72 mm and an inner diameter of 70 mm.
BN and AL Si, TiN 10. WC-g%CO coated with this mixed powder is placed, and diamond particles with an average particle size of 1, u or less and WC are placed in contact with this mixed powder. and Co
The ratio of each is the volume and IQ: /j:
The one filled with a mixed powder of j, the diamond particles with a particle size of 1, u or less, and the ratio of WC and Co is '10:
A mixed powder having a ratio of 30:10 was filled. Both capsules were plugged with Mo and placed in an ultra-high pressure device.
It was heated to /3oo0c and held for 30 minutes. In these obtained sintered bodies, the diamond sintered body part is composed of CBN and Ti.
It was firmly bonded to the cemented carbide base material via an intermediate bonding layer made of N, AI, and Si. A cutting tool of these composite sintered bodies was prepared in the same manner as in Example/, and Vτ1' blue was placed at two locations/f00 interval in the circumferential direction at the cutting material Al-2.
0%s summer speed 700m/rrm.

Cutting was carried out at a depth of cut of 0.30"/rev. For comparison, a commercially available tool sintered body in which a diamond sintered body using CO as a binder was directly bonded to a cemented carbide base material was also cut under the same conditions. Both of the sintered bodies of the present invention did not have their cutting edges chipped or peeled off from the bonding interface even after passing through V grooves 70,000 times, but the commercially available sintered bodies for tools did not peel off from the joint interface after passing through V grooves 700 times. It peeled off more.

(Example 11> WC-Otsu% in an MO container with an inner diameter of Qmm and an outer diameter of 2 mm.
A sintered body of Co composition, outer diameter/Q mm, and height 3 was placed, and on top of it, CBN, TiN, and TaN with an average particle size of Sμ were placed at a weight ratio of 1 kg: jf3:, 2', ', 9. A stamped body of mixed powder with an outer diameter of 70mm and a thickness of Q and jrntn was placed, and on top of this was placed a diamond powder with an average particle size of 7mm and a diameter of 0.
．． 3g was filled. Furthermore, a copper plate with a thickness of 0, 2 mm and a Ni disk with a thickness of θ/2 mm were placed on top of this. A stopper made of Mo was attached and sintered in an ultra-high pressure apparatus at 7300°C for 20 minutes in the same manner as in Example. The obtained sintered body uniformly contains copper and N1, and the diamond sintered body with an outer diameter of about 10 mm and a thickness of 1 mm is bonded to WC- It was firmly connected to the Co cemented carbide base material.

This composite sintered body was heated at 7000° C. for 2 hours in a vacuum, but there was no peeling at the bonded interface, and it was able to sufficiently withstand the same cutting test as in Example.

[Brief explanation of drawings]

Figure 1 is a micrograph of the interface between the diamond sintered body layer and the base cemented carbide of a commercially available diamond sintered body for tools integrated with the cemented carbide base material, and Figure 2 is a photomicrograph of the interface between the diamond sintered body layer and the base cemented carbide. FIG. 3 is a diagram showing the structure of a composite sintered body for a tool. 1... Diamond-containing hard sintered body layer used as a tool cutting edge, 2... WCC cemented carbide as base material 3...
An intermediate bonding layer made of carbide or nitride, which is a feature of the present invention. The details of the drawing...;! −:: :' ! C;゛、"jNo change) Procedural amendment (method) 6. Supplement 1. Indication of the case
[Showa Otsu/Year Patent Application No.≠029 2
, title of invention “
Method of manufacturing composite sintered bodies for tools Class 6 person (2) Relationship to the case Patent applicant Address Kitahama 5-chome/j, Higashi-ku, Osaka Name
(2/3) Sumitomo Electric Industries, Ltd. President Tetsube 4, agent address 5 Otsu O 2-chome, Hiroban, Toyonaka-shi, Osaka Prefecture and "Microphotograph of the interface between the sintered body layer and the base cemented carbide on page 2', line S of the contents description of the drawing thickness" and amend it as follows. "Microscopic photograph of the metal assemblage at the interface between the sintered body layer and the base cemented carbide"

Claims (1)

[Claims] 1. In contact with the cemented carbide base material, cubic boron nitride 5 to 70
A powder in which the weight percent and the balance are carbides, nitrides, carbonitrides of Groups 4a and 5a of the periodic table, or solid solutions or mixtures of two or more of these is prepared in powder form or in an embossed form, or
Alternatively, the cemented carbide base material is coated in advance, and a hard sintered body-forming powder containing 20% or more of diamond by volume is pressed or placed in powder form, and the whole is heated under ultra-high pressure. A method for producing a composite sintered body for tools, characterized by sintering a diamond-containing hard layer and intermediate layer powder by hot pressing at high temperatures, and simultaneously bonding them to a base cemented carbide. 2. Carbides, nitrides, and carbonitrides of Group 4a of the periodic table are M
Claims using non-stoichiometric compounds in which the value of x, when expressed as C_x, MN_x, M(C, N)_x, is 0.98 or less, preferably in the range of 0.9 to 0.5. A method for producing a composite sintered body for tools according to scope 1. 3. The method for manufacturing a composite sintered body for tools according to claim 1, wherein the nitride of Group 4a of the periodic table is TiN_x. 4. In contact with the cemented carbide base material, cubic boron nitride 5-70
The balance is 50 to 99.9% by weight of carbides, nitrides, carbonitrides of groups 4a and 5a of the periodic table, or solid solutions or mixtures of two or more of these, and the balance is 50 to 99.9% by weight of Al or Si or both. A powder containing 0.1 to 50% by weight or more is prepared in powder form or in the form of an embossed body, or it is pre-coated on a cemented carbide base material, and then a hard diamond containing 20% or more by volume of diamond is applied on top of the cemented carbide base material. The sintered body-forming powder is molded or placed in powder form, and the whole is hot-pressed under ultra-high pressure and high temperature to sinter the diamond-containing hard layer and intermediate layer powder, and at the same time, the hard layer containing diamond and the intermediate layer powder are sintered. A method for manufacturing a composite sintered body for tools, characterized by joining it to an alloy. 5. Carbides, nitrides, and carbonitrides of Group 4a of the periodic table are M
Claims using non-stoichiometric compounds in which the value of x, when expressed as C_x, MN_x, M(C, N)_x, is 0.98 or less, preferably in the range of 0.9 to 0.5. A method for producing a composite sintered body for tools according to scope 4. 6. The method for producing a composite sintered body for tools according to claim 4, wherein the nitride of Group 4a of the periodic table is TiN.