JPH0481544B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a novel method for producing a composite metal carbide sintered body. More specifically, the present invention relates to a method for manufacturing a composite metal carbide sintered body mainly composed of silicon carbide. [Background technology] Ceramic sintered bodies obtained from fine powder of silicon carbide have superior mechanical strength at high temperatures compared to conventional metal materials, so they are expected to be used in engines, gas turbines, etc. Ru. Such a sintered body of silicon carbide is produced by adding a small amount of sintering aids such as boron and carbon to fine powder of silicon carbide, uniformly mixing the mixture, cold-forming it, and then molding it in a non-oxidizing atmosphere. A method of heating to 1,900 to 2,200℃ is known (for example,
−32035, Special Publication No. 1984-40109, Special Publication No. 1987-
No. 34147). However, the ceramic sintered bodies obtained by this method lack complete reliability due to large variations in mechanical strength, which is an obstacle to industrial practical application. [Disclosure of the Invention] As a result of intensive studies aimed at solving the above-mentioned problems and manufacturing a ceramic sintered body that has high mechanical strength and small variations in mechanical strength, the present inventors have identified silicon carbide as a raw material. The present inventors have discovered that the above object can be achieved by using composite metal carbide fine powder in which a certain amount of titanium carbide is uniformly mixed at the molecular level, and sintering it after adding and mixing a sintering aid. This is what led to this. That is, the method for producing a ceramic sintered body of the present invention involves injecting and decomposing a decomposable silicon compound, a decomposable titanium compound, and a decomposable carbon compound into a hot gas containing water vapor to form silicon oxides, titanium oxides, and Generates a mixed aerosol containing elemental carbon,
C/(Si+Ti) obtained by collecting the generated dispersoids
70% by weight or more and less than 95% by weight of silicon carbide and 5% by weight or more and 30% by weight of titanium carbide, obtained by heating a carbon-containing composition having a formula weight ratio of greater than 3.5.
To 100 parts by weight of metal carbide fine powder (hereinafter referred to as composite metal carbide fine powder) consisting essentially of less than 0.1
The present invention relates to a method for producing a composite metal carbide sintered body, which comprises adding up to 4.0 parts by weight of elemental boron or a boron compound corresponding to elemental boron and 0.5 to 4.0 parts by weight of elemental carbon, followed by sintering. In the present invention, silicon carbide and titanium carbide in the composite metal carbide fine powder are of course mixed uniformly, and it is desirable that the state substantially corresponds to the "composition" as defined in the "General Examination Standards". The powder is preferably a fine powder with a specific surface area of about 3 to 50 m ² /g. The specific surface area of composite metal carbide fine powder is 3 m ² /
If it is less than g, the driving force for sintering the composite metal carbide fine powder will be insufficient, making it difficult to obtain a dense sintered body. On the other hand, if the powder is extremely fine and has a specific surface area of more than 50 m ² /g, a problem arises in that it is difficult to increase the density of the cold compact before sintering. Note that the specific surface area referred to here is the nitrogen adsorption specific surface area (measured by the so-called BET method), and it goes without saying that a large value generally indicates a small particle size. The composite metal carbide fine powder in the present invention is a carbon-containing composition obtained by the method proposed by the present inventors in JP-A-59-49828, that is, a decomposable metal in a hot gas containing water vapor. A compound (i.e., a decomposable silicon compound and a decomposable titanium compound) and a decomposable carbon compound are injected and decomposed to produce a mixed aerosol decomposed product containing respective aerosols of the metal oxide and elemental carbon, and the resulting dispersion A composite metal carbide can be obtained by heating a carbon-containing composition obtained by collecting metal particles to form a composite metal carbide. Application of the method for producing a carbon-containing composition disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 59-49828 to the method for obtaining a composite metal carbide in the present invention will be described in detail. In order to obtain the composite metal carbide of the present invention by the method described in JP-A-59-49828, a carbon-containing composition must first be obtained. The carbon-containing composition is produced by injecting and decomposing a decomposable silicon compound, a decomposable titanium compound, and a decomposable carbon compound into hot gas containing water vapor to produce a mixed aerosol containing silicon oxide, titanium oxide, and elemental carbon. It can be obtained by generating the dispersoid and collecting the generated dispersoid. Decomposable silicon compounds and decomposable titanium compounds include silicon or titanium halogen compounds,
Among alkyl compounds, alkoxide compounds, acid ester compounds, etc., they easily undergo thermal decomposition, oxidation, or hydrolysis in hot gas containing water vapor to form silicon oxides or titanium oxides. Examples of such decomposable compounds include, for example, decomposable silicon compounds; SiCl ₄ , CH ₃ SiCl ₃ ,
( _CH3 ) _2SiCl2 , ( _CH3 ) _3SiCl , ( _CH3 ) _4Si , _{HSiCl3 ,
H2SiCl2 , H3SiCl} , _SiH4 , _SiF4 , _{SiH2F2 ,}
There are Si ₂ H ₆ , Si ₂ F ₆ , etc., and degradable titanium compounds include; TiCl ₄ , TiBr ₄ , TiI ₄ , TiF ₄ , TiH ₄ , Ti
( _{OCH3 ) 4 ,} Ti _{( OC2H5} ) ₄ , _{CH3TiCl3 , C2H5TiCl3}
Preferred examples include compounds such as, but as mentioned above, the compound is not limited to these as long as it is decomposable in hot gas containing water vapor. The decomposable carbon compound used in the implementation of the present invention is
When charged in hot gas as described later, it can easily decompose to produce elemental carbon (soot), and it can be in a gas or liquid phase as it is, or it can easily change to a liquid phase by increasing the temperature. Those that can become a state can be suitably used. Petroleum products such as LPG, naphtha, gasoline, fuel oil, kerosene, light oil, heavy oil, lubricating oil, liquid paraffin; methane, ethane, propane, butane, pentane, methanol, ethanol, propanol, ethylene, acetylene, n
- Paraffin, butadiene, isoprene, isobutylene, benzene, toluene, xylene, cyclohexane, cyclohexene, dicyclobentadiene, ethylbenzene, styrene, kyumene, pseudocumene, mesitylene, alkylbenzene, α
-Methylstyrene, dicyclododecatriene, diisobutylene, vinyl chloride, chlorobenzene,
Petrochemical products such as _C9 distillate mixtures, ethylene bottoms; tar, pitch, creosote oil, naphthalene, anthracene, carbazole, tar acid,
Tar products such as phenol, cresol, xylenol, pyridine, picoline, and quinoline; soybean oil, coconut oil, linseed oil, cottonseed oil, rapeseed oil, tung oil, castor oil, whale oil, beef tallow, squalane, oleic acid, stearic acid, etc. Preferred examples include oils and fats, but of course they are not limited to these. The decomposable carbon compound used in the practice of the present invention is
Since the purpose is to supply carbon, a wide range of choices can be made for this purpose, for example as described above. However, from the viewpoint of ease of handling and carbon yield, toluene, xylene, benzene, kerosene, light oil, heavy oil, _C9 distillate mixture, ethylene bottom, etc., which have a relatively large carbon content, are particularly preferred. Hot gas containing water vapor can also be obtained by injecting water vapor into hot gas obtained by an electric heating method, high frequency heating method, or electric discharge method, but hydrogen, methane, ethane, etc. The method of using air to combust combustible materials that produce water vapor when burned, such as propane or hydrocarbons used as raw materials, allows hot gas containing water vapor to be obtained in one step, which is simple in terms of equipment and improves thermal efficiency. It is economical in terms of In order to obtain the carbon-containing composition, it is convenient to use a furnace as shown in FIG. The mixed aerosol dispersoid in the hot gas thus obtained is guided outside the furnace, and the solids contained therein are collected by a solid-blast separation operation using a known collection device such as a bag filter, cyclone, or electrostatic precipitator. do. In the present invention, the content of silicon carbide in the composite metal carbide fine powder is 70% by weight or more and less than 95% by weight (hereinafter, % by weight is simply referred to as %), and the content of silicon carbide is 5% by weight.
However, when the composite metal carbide fine powder is obtained from the carbon-containing composition, this content must be adjusted by adding a decomposable silicon compound injected into hot gas containing water vapor and decomposing This can be easily carried out by adjusting the amount of the titanium compound. In the present invention, C/(Si
+Ti) formula weight ratio, i.e. C(g-atm)/(Si+
The ratio of Ti) (g-atm) is preferably greater than 3.5. This is based on the inventors' experimental findings that the more carbon is contained in the carbon-containing composition, the smaller the average particle diameter of the composite metal carbide fine powder obtained by heating the composition becomes. However, this value
If the value is too large, such as exceeding 20, no more significant effect can be obtained, and the result is simply a loss of carbon compounds. C/(Si+Ti)
The formula weight ratio is preferably 3.5 or more and less than 20, more preferably 4 or more and less than 10. The thus obtained carbon-containing composition consisting of silicon oxide, titanium oxide, and elemental carbon can be directly heated in a high-frequency heating furnace or Acheson type in an inert gas atmosphere such as argon, helium, or nitrogen. 1600 ~ depending on current-carrying resistance furnace, etc.
By heating to 2100°C, preferably about 1700 to 1900°C, composite metal carbide fine powder can be obtained according to the following formulas (1) and (2). SiO ₂ +3C→SiC+2CO…(1) TiO ₂ +3C→TiC+2CO…(2) However, it is desirable that the C/(Si+Ti) formula weight ratio of elemental carbon contained in the carbon-containing composition is greater than 3.5. A stoichiometric excess of carbon is included over the amount that produces silicon carbide and titanium carbide according to the above formula. Therefore, an excess of elemental carbon remains in the composite metal carbide fine powder produced here, but the excess elemental carbon can be converted to elemental carbon by heating this fine powder in air to 500 to 1000°C. can be easily removed by combustion. Next, a method for manufacturing a ceramic sintered body from the composite metal carbide fine powder thus obtained will be described. As described in the background art section, the method for producing a composite metal carbide sintered body from a composite metal carbide fine powder in the present invention can be applied to methods commonly used in the ceramics industry and known per se. That is, fine powder obtained by mixing a small amount of elemental boron or a boron compound corresponding to elemental boron and elemental carbon with composite metal carbide fine powder is formed into a desired shape by a method such as pressure molding or casting, and then 1900 It can be made into a sintered body by heating to about 2200°C. Of course, methods such as hot pressing, hot isostatic pressing (HIP), etc. can be used as the sintering method, but the method of heating at a pressure below atmospheric pressure, the so-called normal pressure sintering method, is the most preferred method for industrial use. It's advantageous. The atmosphere during heating is argon,
It is preferable to use an inert gas such as helium or nitrogen, or a vacuum. As mentioned above, in the present invention, the composite metal carbide fine powder preferably has a specific surface area of about 3 to 50 m ² /g. In the present invention, the composite metal carbide fine powder can be obtained by the following method. That is, decomposable metal compounds (i.e.
A decomposable silicon compound and a decomposable titanium compound) and a decomposable carbon compound are injected and decomposed to generate aerosol dispersoids containing respective aerosols of the metal oxide and elemental carbon, and the generated dispersoids are collected. This is a method of heating the carbon-containing composition obtained. The present inventors have confirmed that the effects of the present invention are more significant when using the composite metal carbide fine powder obtained by this method. The composite metal carbide fine powder of the present invention has a composition mainly composed of silicon carbide and contains a specific amount of titanium carbide. As mentioned above, titanium must be 5% or more and less than 30%. The reason for this is that if the titanium carbide content is less than 5%, the state will be similar to that of a fine powder of silicon carbide alone, making it impossible to obtain the effects of the present invention, while if it is more than 30%, it will be difficult to obtain a dense sintered body. This is to become. In the present invention, prior to sintering, as a sintering aid for promoting sintering of the composite metal carbide fine powder,
It is preferable to add and mix a small amount of elemental boron or a boron compound corresponding to elemental boron and elemental carbon. The amount added is 100% of composite metal carbide fine powder.
The former is about 0.1 to 4.0 parts, and the latter is about 0.5 to 4.0 parts by weight. For that purpose, it is desirable to mix the sintering aid with the composite metal fine powder as uniformly as possible. Therefore, elemental boron or a boron compound has a specific surface area of 3 m ² /g or more, and elemental carbon has a specific surface area of 30 m ² /g. It is preferable to use a fine powder such as carbon black or acetylene black, which has a particle size of 1.5 g or more. Mixing is carried out using a ball mill, vibration mill, etc., but in order to obtain a more uniform mixture,
A preferred method is to add water or an organic solvent such as methanol or ethanol and mix the mixture wet using the ball mill, vibration mill, or the like described above. That is, one method is to disperse and suspend elemental boron or boron compound fine powder and elemental carbon fine powder in water or an organic solvent, mix this suspension with composite metal carbide fine powder, and then add water or organic solvent. There is a way to remove it by evaporation. Another method is to add and mix water or an organic solvent to elemental boron or boron compound fine powder, elemental carbon fine powder, and composite metal carbide fine powder, and then remove the water or organic solvent by evaporation. In the present invention, either method can be adopted. In addition, the above-mentioned boron compounds corresponding to elemental boron that can be used in the present invention include B ₄ C,
Preferred examples include BN, AlB ₂ and the like. [Operations and Effects of the Invention] The method for producing a composite metal carbide sintered body of the present invention includes the following steps:
As explained in detail above, this is a method in which a composite metal carbide fine powder consisting mainly of silicon carbide and a specific amount of titanium carbide is sintered in the presence of a sintering aid, and the composite metal carbide is The fine powder injects and decomposes a decomposable silicon compound, a decomposable titanium compound, and a decomposable carbon compound into hot gas containing water vapor to generate a mixed aerosol containing silicon oxide, titanium oxide, and elemental carbon, The composite metal carbide fine powder is obtained by heating a carbon-containing composition having a C/(Si+Ti) formula weight ratio of greater than 3.5, which is obtained by collecting the generated dispersoids. The ceramic sintered body thus obtained has high mechanical strength and has extremely small variations in strength. The detailed reason why such an excellent sintered body can be obtained is, of course, not clear at present, but the inventors of the present invention speculate as follows. According to the theory or common theory that is currently believed in the ceramic industry, in order for a ceramic sintered body to have high mechanical strength and small variations in strength, (1) It is required that (2) each particle constituting the sintered body is uniform and fine in size, as well as (2) that no defects remain. It is presumed that the effect of the present invention is mainly due to the latter, and this is also supported by examining the structural state of the particles constituting the sintered body using SEM photographic images. That is, when comparing the SEM photographic images of the sintered compact obtained by the method of the present invention and the sintered compact obtained by the conventional manufacturing method, it is found that the sintered compact obtained by the present invention is It is confirmed that the sintered body has a much finer structure than conventional sintered bodies. Although it is not necessarily clear why such a fine structure is formed, the present inventors speculate as follows. That is, the ceramic sintered body obtained by the present invention is
Complex metal carbide fine powder injects and decomposes decomposable silicon compounds, decomposable titanium compounds, and decomposable carbon compounds into hot gas containing water vapor to generate a mixed aerosol containing silicon oxides, titanium oxides, and elemental carbon. When the composite metal carbide fine powder is produced by heating a carbon-containing composition having a C/(Si+Ti) formula weight ratio of greater than 3.5 by heating this dispersoid, The effects of the invention are remarkable. The reason for this is that the composite metal carbide fine powder obtained by the above method is in a state in which silicon carbide powder and titanium carbide powder are mixed even more uniformly, so the titanium carbide is dispersed in the composite metal carbide fine powder. This is thought to be because the results are even better. [Preferred Mode for Carrying Out the Invention] The present invention will be described in more detail below with reference to Examples. Example 1 Using the carbon-containing composition manufacturing apparatus shown in FIG.
Air was charged from the duct 2 and propane was charged from the combustion burner 3 at flow rates of 100 Nm ³ /h and 2 Nm ³ /h, respectively, to generate a flame. In addition, SiCl ₄ is used as a degradable silicon compound, and TiCl ₄ is used as a degradable titanium compound.
and heavy oil A were selected as the decomposable carbon compound, and these were mixed in advance at a weight ratio of 1:0.084:2 and injected into the furnace through nozzle 4 at a flow rate of 30 kg/h. The obtained aerosol is led out of the system through duct 6, and the dispersoids in the aerosol are collected and a carbon-containing composition consisting of silicon oxide and titanium oxide is 10.6
A yield of Kg/h was obtained. The carbon-containing composition is
_C /( _Si
+Ti) formula weight ratio was 9.3. 500 g of this carbon-containing composition was heated at 1750°C for 2 hours using a high-frequency heating furnace, and after cooling, it was heated in air to 600°C to burn off the remaining carbon, and then washed with an aqueous hydrofluoric acid solution. 115 g of composite metal carbide was obtained. This composite metal carbide contains 89% silicon carbide and 11
% of titanium carbide, and the specific surface area is 14.7m ² /g.
It was hot. To 100 g of this composite metal carbide were added 1.5 g of B ₄ C fine powder, 2.0 g of carbon black, and 50 c.c. of ethanol, and these were wet-mixed for 20 hours. The resulting mixture was heated to remove ethanol by evaporation, and 80 g of the fine powder obtained was placed in a cylindrical container.
After being uniaxially compressed under a load of 0.5 T/cm ² , it was rubber pressed and molded under a hydrostatic pressure of 2 T/cm ² . Next, this molded body
10 ^-1 ~ 1 torr vacuum at 2050℃ in nitrogen atmosphere, 30
A composite metal carbide sintered body was obtained by heating for a minute. When the density of this sintered body was measured, a sintered body of composite metal carbide was obtained with a density of 3.31 g/cc. Cut this sintered body with a diamond cutter
Twenty test pieces were prepared, and the bending strength was measured at room temperature according to the method of JIS R-1601. As a result, the average bending strength is 72Kg/mm ² and the standard deviation is 3.0Kg/mm ²
It was hot. The internal structure of this sintered body was analyzed using a SEM photograph, and it was confirmed that the sintered body had a much finer structure than that of Comparative Example 1. Comparative Example 1 90 g of silicon carbide with a specific surface area of 1.2 m ² /g and 10 g of titanium carbide with a specific surface area of 0.9 m ² /g were pulverized and mixed for 50 hours using a vibration mill to form a composite metal with a specific surface area of 15.1 m ² /g. 100 g of carbide fine powder was obtained. This composite metal carbide fine powder contains B ₄ C with a specific surface area of 5.3 m ² /g.
1.5 g of fine powder, 2.0 g of carbon black with a specific surface area of 120.5 m ² /g, and 50 c.c. of ethanol were added and mixed wet for 20 hours to obtain a composite metal carbide fine powder and a mixture thereof. . 80 g of the fine powder obtained by heating the resulting mixture to remove ethanol by evaporation was placed in a cylindrical container, uniaxially compressed under a load of 0.5 T/cm ² , and then rubber pressed under a hydrostatic pressure of 2/cm ² . Molded.
Next, this compact was heated at 2050° C. for 30 minutes in a vacuum of 10 ⁻¹ to 1 Torr in a nitrogen atmosphere to obtain a composite metal carbide sintered body. When the density of this sintered body was measured
It was 3.30g/cc. Next, this sintered body was cut with a diamond cutter to prepare 20 test pieces, and the bending strength was measured at room temperature according to the method of JIS R-1601. As a result, the average value of bending strength is 63Kg/ ^mm2 , and the standard deviation is 4.6Kg/mm2.
It was warm in ^mm2 . Comparative Example 2 According to the same method as in Example 1, SiCl ₄ was selected as the degradable silicon compound, TiCl ₄ was selected as the degradable titanium compound, and heavy oil A was selected as the degradable carbon compound, and these were mixed in advance in weight ratio. 1:0.022:
1.8 and injected into the furnace from nozzle 4 at a flow rate of 30 kg/h. The dispersoids in the obtained aerosol are collected to form a carbon-containing composition consisting of silicon oxide and titanium oxide.
The yield was 10.2Kg/h. The carbon-containing composition is
_C /( _Si
+Ti) formula weight ratio was 8.6. This carbon-containing composition was heated and washed to obtain 123 g of composite metal carbide. This composite metal carbide contains 97% silicon carbide and 3
% of titanium carbide, and the specific surface area is 15.6m ² /g.
It was hot. This composite metal carbide was treated in the same manner as in Example 1, and the density of the sintered body was measured, and a sintered composite metal carbide having a density of 3.21 g/cc was obtained. The bending strength of this sintered body was measured. As a result,
The average value of bending strength is 65Kg/mm ² and the standard deviation is 4.5
It was Kg/ ^mm2 . The internal structure of this sintered body was analyzed using a SEM photograph, and grain growth was confirmed in the microstructure compared to that of Comparative Example 1. Comparative Example 3 According to the same method as in Example 1, SiCl ₄ was selected as the degradable silicon compound, TiCl ₄ was selected as the degradable titanium compound, and heavy oil A was selected as the decomposable carbon compound, and these were mixed in advance in weight ratio. 1:0.33:
2.8 and injected into the furnace from nozzle 4 at a flow rate of 30 kg/h. The dispersoids in the obtained aerosol are collected to produce a carbon-containing composition consisting of silicon oxide and titanium oxide.
The yield was 9.2Kg/h. The carbon-containing composition is
_C /( _Si
+Ti) formula weight ratio was 10.4. This carbon-containing composition was heated and washed to obtain 127 g of composite metal carbide. This composite metal carbide contains 67% silicon carbide and 33% silicon carbide.
% of titanium carbide, and the specific surface area is 14.9m ² /g.
It was hot. This composite metal carbide was treated in the same manner as in Example 1, and the density of the sintered body was measured, and a sintered composite metal carbide having a density of 3.71 g/cc was obtained. The bending strength of this sintered body was measured. As a result,
The average value of bending strength is 67Kg/mm ² and the standard deviation is 4.7
It was Kg/ ^mm2 . Production Examples 1 to 4 Four types of composite carbide fine powders were produced by the following method. That is, using the manufacturing apparatus shown in FIG. 1 in the same manner as in Example 1, air was supplied from the duct 2 and propane was supplied from the combustion burner 3 at a rate of 100 Nm ³ /
h, and a flame was generated by charging at a flow rate of 2 Nm ³ /h.
Further, the decomposable silicon compound, decomposable titanium compound, and decomposable carbon compound shown in Table 1 were used, and each was injected into the furnace at the injection amount and nozzle position shown in Table 1. Here, the same injection nozzle number means that the ingredients are mixed in advance and injected from the same nozzle. That is, in Production Example 1, SiCl ₄ was injected from nozzle 4, and Ti
(OCH ₃ ) ₄ and ethylene bottoms mean that they were mixed in advance and injected through the nozzle 5. In Production Example 2, three types of compounds were mixed in advance and injected into the same nozzle 4.
It means more injected. The obtained aerosols are led out of the system through duct 6, and have the production amount, composition, and C/C ratio shown in Table 1.
A carbon-containing composition having a formula weight ratio of (Si+Ti) was obtained. 500 g of each of these carbon-containing compositions was heated at 1750°C for 2 hours using a high-frequency heating furnace in the same manner as in Example 1, and composite metal carbide fine powders having the compositions and specific surface areas shown in Table 1 were obtained. Each product was obtained in the amount shown in Table 1. Examples 2 to 8 Using the peaches obtained in Production Examples 1 to 4 as composite metal carbide fine powders, boron compounds and elemental carbon with the names, specific surface areas, and amounts shown in Table 2 were added to 100 g of each of these. , plus ethanol 50
cc was added and mixed in a vibrating mill for 20 hours. 80 g of fine powder obtained by heating each of these mixtures to remove ethanol was molded and heated in exactly the same manner as in Example 1 to obtain sintered bodies having densities shown in Table 2. Using the obtained sintered body, the bending strength was measured in exactly the same manner as in Example 1. The results were as shown in Table 2. From the bending strength shown in Table 2, it can be seen that by following the method of the present invention, sintered bodies with high strength and small variation can be obtained.

[Table] * Ethylene bottom

【table】

【table】 [Brief explanation of the drawing]

Figure 1 shows Example 1, Comparative Examples 2 and 3, and Production Example 1.
It is a sectional view showing the manufacturing device of the carbon-containing composition used in -4. In the figure, 1... furnace material, 2... duct, 3... combustion burner, 4... nozzle, 5... nozzle, 6... duct are shown.

Claims (1)

[Claims] 1. Injecting and decomposing a decomposable silicon compound, a decomposable titanium compound, and a decomposable carbon compound into a hot gas containing water vapor to generate a mixed aerosol containing silicon oxide, titanium oxide, and elemental carbon,
C/(Si+Ti) obtained by collecting the generated dispersoids
70% by weight or more and less than 95% by weight of silicon carbide and 5% by weight or more and 30% by weight of titanium carbide, obtained by heating a carbon-containing composition having a formula weight ratio of greater than 3.5.
To 100 parts by weight of metal carbide fine powder (hereinafter referred to as composite metal carbide fine powder) consisting essentially of less than 0.1
A method for producing a composite metal carbide sintered body, which comprises adding ~4.0 parts by weight of elemental boron or a boron compound corresponding to elemental boron and 0.5 to 4.0 parts by weight of elemental carbon, and then sintering.