JPH07110789B2 - Method for manufacturing composite ceramics sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a new method for producing a composite ceramics sintered body, in which the Thermite reaction is simply allowed to proceed under pressure,
It is intended to provide a method for controlling a very good and novel ceramic material in which the phase composition of composite ceramics, the structure and distribution of various constituent phases and the crystal grain size are sufficiently controlled by utilizing a large amount of reaction heat obtained in a short time. is there. In particular, the method for producing the composite ceramics sintered body of the present invention, in order to obtain a sufficiently controlled fine structure that cannot be produced by the conventional method for the composition of the final composite phase, along with the utilization of the thermite heat,
The new sintered body obtained by devising the adjustment and selection of the ceramic powder to be sintered is not only used in the conventional field of ceramics, but also used in more severe environments and with higher performance. An extremely useful ceramic composite material in various required industrial fields is provided.

[Conventional technology]

For the production of the composite ceramics sintered body, a method of heating and densifying by sintering for a long time has been conventionally used. The biggest problem in the conventional manufacturing method is that it is not possible to obtain a multi-phase ceramics sintered body that is dense and has fine crystal grains, and various ceramics phase constitution in the sintered body is sufficiently controlled according to the purpose. . To promote the densification, there are pressure sintering methods such as hot pressing (HP) and hot isostatic pressing (HIP), and the high pressure sintering method of heating under higher pressure is also effective. On the other hand, in the vacuum sintering and atmospheric pressure sintering methods, various auxiliaries and the like are used to promote densification, and densification is achieved by a kind of multi-component composite. As described above, the problems in the time-consuming densification sintering are as follows.

(A) Crystal grains become coarse during densification, and pores are likely to remain. Further, the coarsening of the crystal grains tends to cause thermal stress in the sintered body, especially ceramics having strong anisotropy, and cause destruction.

(B) In order to prevent crystal grain coarsening during densification sintering, it is essential to add an auxiliary agent such as a grain growth inhibitor, and these auxiliary agents often deteriorate the characteristics of the sintered body. Even when the sintering raw material is sufficiently modified into a fine powder and grain growth is prevented by low temperature sintering, it takes time to densify and the sintering temperature, time,
Atmosphere control is extremely difficult.

(C) By the measure of (b) above, the crystal grain coarsening of the sintered body can be suppressed, but the automorphism of each phase of the ceramic becomes unclear, and the realization of the intended composite phase structure is significantly restricted. .

As an attempt to solve these problems, in order to reduce the time required for densification, for example, a hot press sintering method (powder and powder metallurgy, Vol. 32, No. .6, 215-218) is used.

Recently, ceramics pressure self-combustion sintering method (High
−Pressure, Self−Combustion Sintering for Ceramic
1967 is a synthetic simultaneous sintering method of ceramics named s).
Using the so-called SHS method (Self-Propagating High Temperature Synthesis), which has been studied in Soviet countries since 2010, it was demonstrated under high pressure (Japanese Patent Laid-Open No. 60-246270 and Comm. Am. Ceram. Soc., C- 224-5, November 1984). SHS
The method is a method of self-heating by a burning exothermic reaction mixture such as thermite composition. For example, in the case of a ceramic material, when this method is used, a compound exothermic reaction is generated from a mixture of constituent elements of the ceramic material. Synthetic sintering without external heating. The attempt of the synthetic co-sintering method is to remove the holes in the ceramic material synthesized by the SHS method by pressure to produce a dense sintered body in a few seconds, and the Ti (titanium) and B (boron) It is reported that a TiB ₂ sintered body was produced under a pressure of 3 GPa only by electric ignition of the pressed mixture. The relative density and hardness of these sintered bodies were 95% and 2000 kg / mm ² , respectively.

Another method of applying pressure is the impact pressure solidification method (Expl
osive shock compaction) combined with the above SHS method,
A method for densely solidifying a ceramic material has been proposed (US Pat. No. 4,655,830). In this method, ceramics synthesis co-sintering is carried out under a high impact pressure of several tens GPa for a short time of μsec level.For example, using a powder mixture of TiO ₂ , carbon, and aluminum as a starting material, 45 GPa is used.
It has been reported that TiC-Al ₂ O ₃ composite ceramics were synthesized by applying impact pressure of a. The microhardness of the obtained sintered body is 50.
It is 0 to 700 kg / mm ² , the interparticle bond is relatively weak, and microcracks are observed in some places.

[Problems to be Solved by the Invention]

To summarize the various recent technologies that have been attempted to solve the above-mentioned problems, for example, (i) the electric current sintering method is effective for conductive ceramics or cermets, but for insulating or semiconductive ceramics. Is not applicable. Further, it is extremely difficult to achieve sufficient control of the crystal grain size and ceramic constituent phases and densification at the same time.

(Ii) Synthetic simultaneous sintering method (High Pressure, Self-Combusti
in Sintering), since the synthesis and pressure sintering proceed only by the exothermic reaction of the compound itself without external heating, an extremely high temperature is generated during the synthetic sintering, and degassing from each element is promoted. Sintered bodies generally tend to become porous as the pressure decreases. In order to reduce this porosity, a cermet (ceramic phase + metal phase) sintered body has recently been attempted to be manufactured (Powder Powder Metallurgical Association, Showa 61).
Autumn Proceedings of the Annual Conference, 42-43).

In addition, because of the so-called self-combustion mode in which synthetic sintering is carried out mainly by mixing elements with extremely large heat of reaction for formation, the synthetic reaction rate is generally very fast, and the stability of other complex phases in the production of complex ceramic phases is Even if the thermodynamic stability of the ceramic phase is taken into consideration, it is difficult to control the constituent phases according to the purpose.

(Iii) In the composite ceramics manufacturing method using the SHS method under impact pressure, the SHS reaction is self-sustaining.
Even in a non-reaction, combustion synthesis sintering is possible due to the sufficiently high pressure generated by shock waves and the high temperature generated between particles, but the pressure application time is extremely short (μsec) and the high temperature generation is mainly localized on the particle surface. Therefore, the SHS reaction is not completed, and the sintered body is liable to be broken due to cracking during rapid pressure reduction (μsec).

The present invention has been made in view of the above-mentioned circumstances, and the object thereof is to achieve sufficient heat generation of the thermite reaction, which can achieve three problems that cannot be overcome by the conventional techniques, that is, densification, fine structure, and control of constituent phases. It is to provide a method for manufacturing a new composite ceramics sintered body using the above.

Another object of the present invention is to sufficiently control the amount of heat input due to heat generation by expanding the types of thermite reaction to be utilized,
An object of the present invention is to provide a method for producing an excellent composite ceramics sintered body in which the ceramic constituent phases in the sintered body are sufficiently controlled by heating for a short time.

Further, the object of the present invention is to continue the manufacturing process of the composite ceramics sintered body utilizing the heat generation of the thermite reaction, and to obtain extremely fine pores without changing the microstructure, phase structure or structure of the sintered body. It is an object of the present invention to provide a method for producing a composite ceramics sintered body which can improve performance and reliability by reducing

[Means for Solving the Problems]

To achieve the above object, according to the first aspect of the present invention, (A) at least one ceramic powder and (B) at least one selected from carbon, boron and silicon
A composite ceramic calcination, characterized in that a mixture of one or more kinds of non-metal powder and (C) metal powder and / or a non-metal powder different from (B) above is heated and sintered under heat of thermite reaction under pressure. A method of making a conjugate is provided.

According to the second aspect of the present invention, in the method, the thermite composition for heating the powder mixture to be sintered is a mixture of copper oxide powder and aluminum powder, or a mixture of iron oxide powder and Si powder in this mixture. There is provided a method for producing a composite ceramics sintered body, which is characterized by comprising a combination thereof.

According to the third aspect of the present invention, the microstructure, phase composition, structure, etc. of the obtained composite sintered body are changed following the manufacturing process of the composite ceramics sintered body utilizing the heat generation of the thermite reaction by the above method. To reduce porosity, improve reliability, and improve performance without increasing the temperature from 500 to 1700 ℃, 200 to
Provided is a method for producing a composite ceramics sintered body, which comprises performing hot isostatic pressing or hot pressing for 5 to 60 minutes in a pressure range of 2000 atm.

[Operation and Mode of Invention]

In the method for manufacturing the composite ceramics sintered body of the present invention,
A mixture of (A) ceramic powder and (B) non-metal element powder selected from carbon, boron and silicon and (C) metal powder and / or non-metal element powder different from (B) above is heated at high temperature for a short time. The heating is performed by a so-called thermite composition, which is a chemical reaction that can be indirectly achieved. The exotherm of the Thermit reaction was used as the heat source. Although a method for sintering ceramic powder or metal powder, or a mixture of ceramic powder and metal powder is disclosed in JP-A-61-186404 and U.S. Patent Application No. 928,220, it exists in the powder mixture to be sintered. Unlike the non-metal element powder and the metal powder and / or the former, the non-metal element powder generates a new ceramic phase by thermite reaction heat, and the obtained ceramic composite has the ceramic powder and the non-metal element powder, the metal powder or the former. A highly controlled composite ceramics manufacturing technique capable of sufficiently controlling the phase structure and the fine structure according to the purpose and densifying by appropriately mixing different non-metal element powders has not been developed yet.

Like the method of the present invention, the advantage of thermite heating in the production of composite ceramics is that the non-metal element powder and the metal powder and / or the non-metal element powder and / or the former are different from each other by introducing a large amount of heat into the powder mixture to be sintered in a short time. The point is to promote the generation of a new ceramic phase by the instantaneous binding of the metal element powder. For example, in the usual method of synthesizing a ceramic phase, a composite ceramic sintered body can be manufactured by appropriately controlling the final constituent phase by appropriately selecting the composition of the initial mixed powder even in the change of the generated phase governed by the diffusion phenomenon. In the method for producing a composite ceramics sintered body using the present thermite heating, excellent characteristics of the starting ceramics powder, for example, while maintaining the particle size,
It becomes possible to manufacture a compact and unprecedented composite ceramic sintered body while controlling the amount of intermediate products and stabilizing the phase composition to generate the desired new ceramic phase.

The best mode of the present invention will be described below.

A sintering method utilizing a so-called thermite reaction, which is a chemically exothermic reaction capable of attaining high temperature heating in a short time, is disclosed in Japanese Patent Laid-Open No. 61-
No. 186404. It has been clarified that the thermite composition disclosed by the above-mentioned sintering method is effective in using iron oxide as an oxide and Al, Si, Ti, Mg, Ca, etc. as a reducing metal powder. An example of these reactions is shown by the following formula, for example.

Fe ₂ O ₃ ＋ 2Al → Al ₂ O ₃ ＋ 2Fe ＋ 204kcal (1) On the other hand, the preferred thermite composition used in the present invention has a reaction of 3CuO + 2Al → Al ₂ O ₃ ＋ 3Cu + 289kcal (2) as the main chemical reaction heat source. As compared with the Al thermite composition of the chemical reaction represented by the formula (1), the heat of reaction that can be effectively taken out per 1 mol of Al is advantageously increased by about 40%. In igniting the thermite composition, the Si thermite composition (1 mol of Si
Ignition energy can be reduced by using it together with the powder and a mixture of 2/3 mol of iron oxide), and for example, the electric heating and ignition power by the heater can also be reduced. In the manufacturing method of the present composite ceramics sintered body, the thermite composition is not limited to the mixture of the copper oxide powder and the aluminum powder, various thermite composition mixture disclosed in JP-A-61-186404. Of course, the body can be used as a heat source for sintering, but the thermite composition comprising a mixture of copper oxide powder and aluminum powder is the most preferable because the amount of chemical reaction heat that can be effectively taken out per filling amount of the thermite composition is large. .

〔Example〕

Hereinafter, the method for producing a composite ceramics sintered body according to the present invention utilizing the above-mentioned thermite reaction will be described in more detail according to the following examples.

Example 1 3.2 g of TiB ₂ powder having an average particle size of 1 μm (manufactured by Hermann C. Starck) and about 2.9 g of Ni powder having an average particle size of 0.05 μm (manufactured by vacuum metallurgy)
And boron powder with an average particle size of about 0.5 μm (made by Shellac)
0.64 g was weighed and used as a mixed raw material for producing a composite ceramics by a thorough mixing method.

1.85 g of this mixed powder was sampled and cold isostatically molded into a disk shape having a diameter of 12.8 mm to prepare a mixed mass to be sintered. As the thermit composition, 22.9 g of the thermit composition, which is a mixture of copper oxide powder and Al powder in a molar ratio of 3: 2, is divided into two and the diameter is 3
Cold-molded to 0 mm, 7.5 g of the same composition has an outer diameter of 30 mm and an inner diameter of 22 m
It was cold-molded into a cylinder of m and placed through a thin layer of hexagonal boron nitride. Thermite composition 6 g of Si thermite composition (1 mol
A mixture of Si powder and 2/3 mole iron oxide powder, the same in the examples below) was placed and the assembly was filled into a belt-type high pressure generator. FIG. 1 shows the state of arrangement in the high pressure generator. Reference numerals 1 and 2 respectively form a high-pressure generating container with a cylinder and anvil. 3 is a pyrophilant gasket for sealing the pressure. Reference numeral 4 is a pyrophyllant heat insulating material. 5, 6 and 7 are a steel plate, a steel ring and a molybdenum plate respectively, and 8 is a ceramic heat insulating material, which constitutes an assembly for supplying electricity to the carbon energizing wire 9. 10 is a pyrophyllite heat insulating material, 11a and 11b are cylinders and thin layers made of hexagonal boron nitride and carbon black, respectively, 12 thermite composition consisting of copper oxide and aluminum powder, and 13 Si thermite composition and heater It also serves to prevent reaction with the powder to be sintered (a mixture of TiB ₂ and Ni and B powder) 14 and to electrically insulate. A load is applied to the facing anvil to generate a pressure of 20,000 atm in the sample chamber, and then the heater is energized from the facing anvil to heat the sample chamber. In this example, by locally heating the thermite composition by applying an electric power of about 1 kw,
It was revealed that the thermite composition spontaneously ignites in the order of the Si thermite composition and the Al thermite composition (copper oxide + Al powder mixture) to solve a large amount of reaction heat. The thermite calorific value in this example was 33.8 kcal. The heating and sintering of the powder to be sintered by thermite reaction heat was completed when the change of the distance between the anvils was stopped, and after cooling the sample part, the pressure was removed to recover the TiB ₂ -based composite ceramics sintered body.

The composite powder to be sintered shown in this example was a dense sintered body and had a bulk density of 5.02 g / cm ³ . As a result of identifying the composite phase constituting the sintered body obtained by powder X-ray diffraction, it was confirmed to be a pure two-phase composite sintered body of TiB ₂ and NiB.

FIG. 3 (B) shows the result of observing the fine structure of the composite ceramics sintered body obtained in this example by an electron microscope.
Abnormal grain growth of TiB ₂ ceramic particles has not occurred at all,
It can be seen that the NiB ceramics are bonded very well while having an average particle size of 1 μm. Conventional Ti
In the B ₂ —Ni—B system composite ceramics sintered body, a dense sintered body in which the fine structure and the phase structure are sufficiently controlled as described above has not been obtained.

As a comparative example, FIG. 3 (A) shows a microstructure of a sintered body obtained by the normal high-pressure sintering method using the same starting material. The sintering pressure is likewise 20,000 atm. The high-pressure sintering method can forcibly remove the holes of the powder to be sintered by the pressure through the gentle heating process of the powder to be sintered to promote densification. Grain growth of TiB ₂ particles was significantly accelerated as the sintering temperature exceeded 1550 ° C and the densification progressed, and the TiB ₂ particle diameter of the starting material grew several times to 10 times during sintering. I will end up. TiB ₂ crystal is known to be a ceramic with a particularly strong crystallographic anisotropy, and the TiB ₂ / TiB ₂ contact area increases due to abnormal grain growth, and at the same time it forms a composite with a Ni-based boride. As a result, significant thermal stress is generated in the interim, and the susceptibility to fracture is also increased. On the other hand, in such a time-controlled sintering process, it becomes difficult to uniquely and stably control the phase of the Ni-based boride.

TiB ₂ -Ni-B prepared by the high pressure sintering method shown in FIG.
The system sintered body is 1450 because it suppresses the abnormal grain growth of TiB ₂ particles.
Although it was sintered at ℃ for 10 minutes under the pressure of 20,000 gas, the TiB ₂ particles were not uniformly dispersed, and many pores (pores) similar to those of TiB ₂ particles were observed. It was Also, powder X
As a result of examining the phase composition of the composite sintered body by line diffraction,
It consists of three phases of B ₂ , NiB, and Ni ₄ B ₃ , and even if the various sintering conditions (time, temperature) are optimized, pure 2-phase TiB ₂ -NiB as shown in Fig. 3 (B). The manufacture of microstructures has been extremely difficult.

The volume fraction ratio of the TiB ₂ —NiB sintered body showing the fine structure in FIG. 3 (B) is approximately 6: 4. Other properties obtained were micro-Vickers hardness of 14.5 GPa and 800 ° C.
Average thermal expansion coefficient was 7.7 × 10 ^-6 / ℃ and thermal conductivity at 800 ℃ was 0.39 W / cm ℃.

Example 2 CrB powder having an average particle diameter of 2 μm (manufactured by Nippon Shinkin Co., Ltd. with additional pulverization), Ni powder having an average particle diameter of 2 μm and boron powder having an average particle diameter of 0.5 μm were 3.43 g and 2.81 g, respectively. 0.62g
Was mixed in the same manner as in Example 1 and 2.1 g was collected to prepare a mixed mass to be sintered similar to that in Example 1.

This sintered mixed mass was applied to a piston-cylinder type press as shown in Fig. 2 and a Si thermite composition and an Al thermite composition consisting of Al powder and copper oxide powder (total calorific value 33.8 kcal).
The thermite composition was ignited by energizing the current-carrying wire 25 after filling the same with 2000 atmospheres and pressurizing the current-carrying wire 25 to manufacture a composite sintered body. In FIG. 2, 21 is a cylinder, 22 is a pressure punch, 23 is a plate, 24 is a cylinder, 25 is a conducting wire, 26
Is a Si thermite composition, and 27 is the above Al thermite composition. Reference numeral 28 is an intervening layer that prevents the sintered body from being corroded by molten copper of the thermite composition, and 29 is a mixed powder sample to be sintered.

The microstructure of the obtained sintered body is shown in FIG. 4 (C).

According to the X-ray diffraction results, this sintered body is CrB, (Cr, Ni)
_{3 B 4, (Ni, Cr} ) 4 B 3, which is composed of (Ni, Cr) B phase, the fracture toughness was about 6MNm ^-3/2. It can be said that the sintered body is of quite good quality, except that the sintered body has pores of 10 μm or less that are thought to be bubbles. This sintered body is 800
As a result of heat treatment in the atmosphere at ℃, it showed quite good oxidation resistance.

The microstructures of the sintered bodies shown in FIGS. 4 (A) and 4 (B) were respectively sintered by vacuum sintering and SHS reaction which is not self-sustaining under 2000 gas by thermite reaction as above. It is a fine structure of the Cr-Ni-B system composite sintered body in the case.

In the case of a sintered body of the same Cr / Ni / B ratio (a raw material is a mixture of 2 μm CrB and 1 μm NiB) that was vacuum-sintered at 1500 ° C., as shown in FIG. cr, Ni) ₃ B ₄ phase is abnormal growth, the sintered body becomes extremely brittle (K _IC <2MNm ^-3/2). On the other hand, Cr, Ni, B each element powder Cr: 5.1g, Ni: 1.56g,
B: 1.35 g was mixed in the same manner as in Example 1, 1.8 g was sampled to form a mixed lump to be sintered, and a composite sintered body was manufactured under the same conditions as in Example 2. The characteristic of this sintering method is that it is sintered by using thermite reaction heating for the SHS reaction which proceeds from all elemental powders that are not self-sustaining, but as shown in FIG. 4 (B). , A very large amount of bubbles of about 10 μm are generated, and it is hard to say that it is a dense sintered body. The results of comparison of the microstructures of the sintered compacts by these various methods show that the sintered compact (FIG. 4 (C)) manufacturing method of the present Example 2 is an extremely excellent method for manufacturing a composite ceramics sintered compact. ing.

Example 3 Ti powder having an average particle size of 3 μm as a metal powder, 0.5 μm boron powder as a non-metal element powder, and an average particle size of 1 as a ceramic powder.
Using TiB ₂ powder of μm, the volume ratio of the mixture of Ti powder and boron powder (adjusted to have an atomic ratio of Ti and boron of 1/1) to 20% with respect to TiB ₂ ceralac powder was performed. Example 1
A mixed powder to be sintered was prepared by using the mixing method shown in, and 2 g of the powder was sampled and cold isostatically pressed into a disk having a diameter of 12.8 mm to prepare a mixed mass to be sintered. As the thermite composition, a thermite composition composed of a Si thermite composition and a mixture of Al powder and iron oxide (total heat amount of 43.8 kcal) was used, and the thermite composition was filled in a piston-cylinder type press machine shown in FIG.
A composite sintered body was manufactured in the same manner as in Example 2 at 00 atm.

TiB ₂ ceramic is known as a high-melting-point difficult-to-sinter ceramics, and it is extremely difficult to sinter by controlling the denseness, the microstructure, and the phase structure by the ordinary sintering method. If it is used, for example, the following composite ceramics sintered body can be obtained with a dense and finely controlled microstructure.

When the phase constitution of the sintered body was examined by powder X-ray diffraction,
It was clarified that it was a two-phase composite sintered body of TiB ₂ phase and TiB phase. As a result of examination by both means of the X-ray diffraction result and the photoelectron spectroscopy result by XPS, the presence of unreacted Ti and B could not be confirmed. The TiB ₂ particles were about 1 μm, and almost no grain growth was observed.

Example 4 Similar to Example 3, except that B ₄ C (manufactured by Denki Kagaku Co., Ltd.) having an average particle size of 0.8 μm was used as the ceramic powder, Ti as the metal powder and boron as the non-metal element powder were B ₄ C ceramic powder. , The mixture (the atomic ratio of Ti and B is adjusted to 1/2) is mixed so that the volume ratio is 30%, 1.5 g is sampled, and a disk-shaped plate with a diameter of 12.8 mm is fired. A mixed lump was prepared. These sintered mixed lumps were filled in the high-pressure generator shown in Example 1, pressurized to 20,000 atm, and then subjected to a thermite exothermic reaction by the same combination of the Si thermite composition, the copper oxide powder and the Al powder mixture. Sintered.

According to the powder X-ray diffraction results, the sintered body obtained in this example is composed of _two pure phases of B ₄ C and TiB ₂ , and the presence of other unreacted starting materials and the like was not recognized. . The obtained composite sintered body was dense, each crystal grain of B ₄ C and TiB ₂ was about 1 μm, and the dispersion of B ₄ C was uniform. The micro Vickers hardness of the sintered body was 3200 kg / mm ² .

Example 5 MoSi ₂ (made by Nippon Shinkin Co., Ltd.) having an average particle size of 2 μm was used as the ceramic powder, and 0.01 μ as the non-metallic element powder.
m carbon black (manufactured by Cabot) and 0.1 μm amorphous silicon (manufactured by Komatsu Electronics Metals)
The volume ratio of the mixture of silicon and carbon black to Si ₂ powder is 30%, 2.5g is sampled from the mixture and the diameter is 12.8mm.
Was molded into a disk shape to obtain a mixed mass to be sintered. This sintered mixed mass was filled in the high-pressure apparatus shown in Example 1, and a composite ceramics sintered body was produced under the pressure of 20,000 atmospheric pressure under the same thermite exothermic reaction conditions as shown in Example 4.

The obtained sintered body was dense and almost no grain growth of MoSi ₂ particles was observed. The result of the powder X-ray diffraction is MoSi ₂ ,
In addition to the SiC (β) phase, a small amount of Mo ₂ C phase was confirmed. When manufacturing this sintered body, carbon black is the Si / C ratio.
Excessive mixing of about 10% from 1/1 does not show the presence of free Si. It was confirmed by a heating experiment at 1000 ° C. in air that this sintered body was a good sintered body having excellent heat resistance and oxidation resistance.

Example 6 Al ₂ O ₃ powder having an average particle size of 3 μm (ceramic powder was pulverized into a material manufactured by Showa Denko KK and its particle size was adjusted) was used as the non-metal element powder in carbon black and metal. Ti powder having an average particle size of 3 μm was used as the element powder, and the volume ratio of the carbon black and Ti powder mixture to the Al ₂ O ₃ powder was 40%.
A composite ceramics sintered body was manufactured under the same conditions as in Example 5, except that the percentage was changed to (sintered weight of 1.5 g).

The obtained sintered body was extremely dense and X-ray diffraction revealed that Al ₂ O ₃ ,
It was confirmed to be a TiC two-phase composite sintered body. The crystal grain sizes of the respective phases were 3 μm and 1 to 3 μm, respectively, and it was confirmed that extremely good interparticle bonding was achieved. The micro Vickers hardness of the obtained sintered body is
It was 1700 to 1800 kg / mm ² at 200 g.

Example 7 ZrO ₂ powder (1.94 μm) having an average particle diameter of 0.02 μm was used as ceramic powder.
Tetragonal powder stabilized with mol% Y ₂ O ₃ ) as non-metallic elemental powder of boron having an average particle size of 0.5 μm, and metallic powder of 3 μm
A composite ceramic was produced under the same conditions as in Example 5, except that the Ti powder of No. ₃ was used and the volume ratio of the boron powder and the Ti powder mixture to ZrO ₂ powder was 30% (sintering weight 1.8 g).

The obtained sintered body was composed of dense and fine crystal grains as in Example 6, and the fracture toughness value K _IC of the obtained sintered body was 8 MNm.
It was ^-3/2 .

Example 8 Carbon black and amorphous silicon used as a non-metallic element powder in Example 5 were β-Si ₃ N ₄ powder having an average particle size of 0.65 μm and an α phase% of 1% (produced by Hermannsee Stark) as the ceramic powder. 40% volume ratio of silicon and carbon black mixture to β-Si ₃ N ₄ powder
As a result, a mixed powder to be sintered was obtained. From this mixed powder, 1.6 g was sampled to obtain a disc-shaped mixture to be sintered having a diameter of 12.8 mm. Example 1 except that the calcined amount of the present sintered mass was charged into the high-pressure apparatus shown in the example, and the calorific value of the thermite composition and the thermite composition composed of the iron oxide and Al powder mixture was 33.8 kcal. A composite ceramics sintered body was manufactured under the same conditions.

The obtained composite sintered body was composed of a fine mixture of β-Si ₃ N ₄ and β-SiC, and the interparticle bond was firm. When the micro Vickers hardness (200g load) of the sintered body was measured
A value of 2100 kg / mm ² was obtained. As a result of X-ray diffraction, unreacted substances of silicon and carbon were not confirmed.

Example 9 In order to reduce the porosity and improve the properties of the TiB ₂ —NiB ₂ phase composite sintered body obtained in Example 1, 2000 in an Ar atmosphere.
Atmospheric pressure HIP treatment was applied. The HIP temperature was 800 ° C. and the pressurization time was 30 minutes. The bulk density after HIP treatment increased by about 10%. The thermal conductivity at 800 ℃ increased to 0.50w / cm ℃. The effect of the similar treatment was also confirmed in the hot press treatment. In this hot press process, 90
The bulk density was increased by a few percent and the thermal conductivity was also improved by about 10% by pressurizing at 200 atm for 20 minutes at 0 ℃.

The TiB ₂ —TiB sintered body shown in Example 3 was also subjected to HIP treatment in an Ar atmosphere at 2000 atm and 1700 ° C. for 15 minutes, whereby the fracture toughness value K _IC of the sintered body was also about 3 to 5 MNm ^{−3. As a result} , the fracture mode was also changed from the intragranular fracture mode to the intergranular fracture mode. However, the HIP temperature is 1
This treatment, which exceeds 700 ° C or the HIP time exceeds 60 minutes, is not preferable because it significantly changes the fine structure of the sintered body and is poor in economic efficiency. As shown in this Example, following the production of the present composite sintered body, reduction of the porosity of the sintered body, improvement of reliability and performance without changing the microstructure of the composite sintered body, phase composition, etc. HP and HIP treatments are extremely effective means for producing high-performance composite ceramics.

〔The invention's effect〕

As described above, according to the method for producing a composite ceramics sintered body of the present invention, it is extremely difficult to produce by a normal sintering method.
It is possible to manufacture an extremely good quality and novel ceramic material in which the fine structure, phase constitution, structure, phase distribution, etc. of the composite ceramic sintered body are sufficiently controlled.

Further, in order to achieve such an effect, the combined use of the extremely short-time sintering method that effectively utilizes the thermite reaction heat and the adjustment method that devises the powder to be sintered is an extremely effective means. It is also possible to manufacture the new composite ceramics sintered body. As a result, industrially very useful materials can be manufactured. For example, TiB ₂ -NiB shown in the examples
The sintered body was obtained by controlling the fine structure by a conventional method and could not be obtained as a pure two-phase composite sintered body.
Utilizing glass resistance, it can be applied to high temperature glass molding parts. On the other hand, B ₄ C-TiB ₂ sintered body, because of its excellent high hardness and oxidation resistance and aluminum resistance, cutting tools, it can be applied to molten aluminum parts. In addition, the Si ₃ N ₄ —SiC composite sintered body can also be used as a high temperature structural component due to its excellent fine structure uniformity.

According to the method for producing a composite ceramics sintered body of the present invention,
The following remarkable effects can be obtained.

Rapid heating under pressure is possible, and part of the powder to be sintered forms a ceramic phase under controlled temperature, pressure, and time, so the composition of the ceramic phase, phase structure, distribution of each phase, etc. Is fully controllable.

The heating time is short and grain growth is suppressed.

The input heating power for sintering can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of an essential part of an ultrahigh pressure apparatus for carrying out the method for producing a composite ceramics sintered body of the present invention.
The figure is a schematic vertical cross-sectional view of a main part of another piston-cylinder type pressure device for carrying out the method for producing a composite ceramics sintered body of the present invention, and FIGS. 3 and 4 are obtained by examples and comparative examples. 3A is an electron micrograph of a crystal structure of the obtained composite ceramics sintered body, and FIG. 3A is a microstructure of a TiB ₂ —Ni—B system sintered body obtained by a high pressure sintering method, FIG. (B) is a microstructure of a TiB ₂ —NiB composite ceramics sintered body obtained by the method for producing a composite ceramics sintered body of the present invention, and FIG. 4 (A) is Cr— obtained by a vacuum sintering method.
Microstructure of Ni-B composite sintered body, Fig. 4 (B) is a composite sintered body of the same composition obtained by heating and sintering the SHS reaction which is not self-sustaining by thermite reaction at 2,000 atm. Microstructure, FIG. 4 (C) shows the microstructure of the composite ceramics sintered body obtained by the method for producing a composite ceramics sintered body of the present invention (under 2000 atmospheres).

Claims (3)

[Claims] 1. (A) at least one or more ceramic powders; (B) at least one or more non-metal powders selected from carbon, boron and silicon; (C) metal powders and / or the above. A method for producing a composite ceramics sintered body, which comprises heat-sintering a mixture of a non-metallic powder different from (B) with heat generated by a thermite reaction under pressure. 2. The thermite composition for heating the powder mixture to be sintered is a mixture of copper oxide powder and aluminum powder,
2. The method for producing a composite ceramics sintered body according to claim 1, wherein the mixture is a mixture of iron oxide powder and Si powder. 3. A microstructure, phase composition, and structure of the obtained composite sintered body, following the manufacturing process of the composite ceramics sintered body utilizing the heat generation of the thermite reaction according to claim 1 or 2. In order to reduce porosity, improve reliability, and improve performance without changing the temperature, etc., hot isostatic pressing or hot pressing is performed at 5 to 60 at a temperature of 500 to 1700 ° C and a pressure range of 200 to 2000 atm. A method for producing a composite ceramics sintered body, characterized by performing the division.