JPS593955B2 - Method for manufacturing high-strength, heat-resistant silicon compound fired moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a high-strength, heat-resistant silicon compound fired molded body.

In particular, the present invention provides a novel inorganic silicon compound sintered molded product that significantly improves the mechanical strength at high temperatures of a sintered molded product of a heat-resistant inorganic silicon compound such as SiC, Si3N4, MOSi2, etc., and also improves thermal shock resistance. This relates to a method of manufacturing a body.

In recent years, as typified by the development of ceramic materials for high-temperature gas turbines, many attempts have been made to utilize ceramics under harsh conditions that conventional metal materials cannot withstand. Ceramics generally withstand high temperatures and have excellent wear resistance, but their biggest drawback is that they are brittle compared to metal materials, and were considered unsuitable as high-stress structural materials. Through research and development, ceramics that can withstand considerable stress are being developed. Among these ceramics, SiC and Si3
Silicon compounds such as N4 have particularly high temperature strength, thermal shock resistance,
Due to its excellent oxidation resistance, abrasion resistance, corrosion resistance, etc., it is considered to be the most promising material for the above-mentioned high-temperature, high-stress structural material or as a heat-resistant and wear-resistant material, and there are many development studies regarding the silicon compound. Molded bodies made of these silicon compounds are generally produced by heat treatment of pressed powder bodies, but in order to obtain the above-mentioned high-strength materials, it is important to first produce a molded body with as high a density as possible. It is believed that there is, and conventional research and development has been conducted in a direction along with this purpose.

However, for example, SiC and Si3N4 have very poor self-sintering properties, so it is necessary to add an appropriate binder to make them dense, and the use of such a binder introduces impurities into the product. Although high density can be achieved by incorporating these impurities, there is a drawback that the presence of these impurities causes a decrease in high-temperature strength.

For example, the above-mentioned circumstances will be explained below regarding conventionally obtained high-density silicon compound molded bodies using SiC and Si,N4 as representative examples.In the production of SiC molded bodies, Al,
Fe, Y, O, B, etc. are used as binders, and high-density compacts are obtained by sintering or hot pressing at normal pressure or in vacuum. Recently, a method for obtaining a high-density molded body by permeating Si vapor during the high-temperature firing process of a mixed powder of SiC and carbon (0) has been developed, and this product is called 胛-SiC.This molded body is an example of As will be described later, the density is as high as 3.109/d, and its mechanical strength is, for example, a transverse rupture strength of 17.6 kg/11 td up to 1200°C, which is superior to products using other binders mentioned above. However, it is inevitable that 2 to 5% by weight of metallic Si remains in the molded product obtained by this manufacturing method.
When this product is used in an oxidizing atmosphere, this residual S
Since i becomes SiO2 at high temperatures and is present in the molded product, if it is used for a long time in a highly oxidizing atmosphere, it will cause a significant decrease in the strength of the molded product. Next, Sl3Nl is MgO, Al2O3, Y! 03
Mg
In molded products using O, a vitreous phase of SiMgO3 is formed at high temperatures, so high density can be achieved, but the high-temperature strength has the drawback of being significantly reduced due to the softening of this vitreous phase.

Also, when Al2O3 is used as a binder, S! A solid solution phase consisting of -Al-0) appears and high density is achieved, but the strength of this solid solution phase at high temperatures is low, making it unsuitable as a practical material. In addition, hot press molded products using Y2O3 or Y2O3-A'203 as a binder are manufactured with the aim of improving strength at high temperatures, but both
At present, it is not possible to improve the drawback that the strength rapidly decreases from 00 to 1000°C. As mentioned above, in order to obtain a molded product with excellent high-temperature strength, it is necessary to select a suitable combination of base powder and binder that does not produce phases that would cause a decrease in strength at high temperatures. Must.

An object of the present invention is to provide a method for producing a silicon compound fired molded body having excellent high-temperature mechanical properties, which is produced based on suitable selection of the above-mentioned base powder and binder. . In order to achieve the above object, the present invention is made by baking a mixture of the above-mentioned silicon powder and adding an organosilicon polymer compound whose main skeleton components are silicon and carbon as a binder to form a molded body. 500, which was converted and produced from the organosilicon polymer compound, was added to the grain boundary portion of the molded body.
By filling β-SiC fine particles of 0A or less and β-SiC of 100 μm or less produced by a reaction between the silicon powder and free carbon produced in the firing process of the organosilicon polymer compound, the heat-resistant silicon compound and SiC 2. A method for producing a fired molded body having excellent mechanical properties at high temperatures, and further comprising: impregnating the fired molded body with the organosilicon polymer compound used as the binder and then firing it. This relates to producing a fired molded product with higher density and higher performance.

Next, the present invention will be explained in detail.

The fired compact of the present invention is composed of one or more types of powder particles selected from heat-resistant inorganic silicon compounds and two types of β-SiC particles occupying the grain boundaries, so it is different from the conventional product described above. As will be described later in Examples, the properties of the fired molded product of the present invention, which is composed of a substance that has properties similar to those of rice at high temperatures, are extremely superior compared to conventional similar products. , these compacts can be used as high mud materials, e.g. for high temperature gas turbine components?
The scope of application is expected to be extremely wide.

Next, the method for manufacturing the molded article and various chemical changes during the manufacturing process will be described below.

The starting materials for producing this molded body mainly consist of heat-resistant inorganic silicon compound powder and metal silicon powder as shown in Table 1 as representative examples, as well as silicon and carbon added as binders. It is mainly composed of an organosilicon polymer compound as a skeleton component. As a heat-resistant inorganic silicon compound,
In addition to those listed in Table 1, a special feature is that there is no phase or the like that has a composition different from these, which would particularly cause a decrease in mechanical strength. That is, the fired molded product of the present invention inherently has mechanical strength at high temperatures, oxidation resistance,
Since it is composed of an inorganic silicon compound and SiC that have excellent wear resistance and corrosion resistance, and have relatively low reactivity with other substances, the molded product as a whole also has the above-mentioned excellent high-temperature properties. It is something. Next, among the heat-resistant inorganic silicon compounds constituting the fired compact of the present invention, representative ones are shown in Table 1.

For example, simple compounds such as MO2Sl, MO, Si2, composite compounds such as SiC-Si3N4 or SiC-MOSi2, and silicon compounds containing small amounts of other heat-resistant ceramics or high-melting point metals. powder can be used.

In addition, it is advantageous for the particle size of these silicon compound powders to be as small as possible, as this will not create intragranular pores from the beginning or during the firing process, resulting in excellent high-temperature strength and heat-resistant molded bodies. However, this does not apply if obtaining fine powder particles would cause a significant economic disadvantage. Furthermore, it is desirable that the chemical purity of these powder particles be as high as possible, but similarly to the above, if it is economically disadvantageous, particles of relatively low purity can also be used. Regarding metallic silicon powder, as mentioned above, the finer the particles and the higher the purity, the more advantageous it is to improve the performance of the molded product, but if there is a significant economic disadvantage, use lower purity particles as long as the particles are 100 Itm or less. can also be used.

The above-mentioned inorganic silicon compounds and metal silicon powders are commercially available and are advantageous because they can sufficiently achieve the purpose and are easily available raw materials. Next, a binder made of an organosilicon polymer compound whose main skeleton components are carbon and silicon will be explained.

The organosilicon compound that can be used as a starting material for the organosilicon polymer compound whose main skeleton components are silicon and carbon used in the present invention is selected from those classified into the following types (1) to al. It consists of one or more of the following.

(C) Compound silahydrocarbon containing only SiC-C bonds (
R4S called SilahydrOOarbOn)
i, R3Si(R'SiR)NR'SiR2, etc. and their carbon monofunctional derivatives belong to this category.

(2) Compounds containing Si-H bonds in addition to Si-C bonds, such as mono-, di-, and triorganosilanes, belong to this category.

(3) Compounds having Si-Hal bonds Organohalogenosilanes other than monosilane.

Example CH2= CHSiF3, C2H5SiHCl2, (
CH3)2(CICH2)SiSi(CH3)2
This includes C1, (C6H,)3SiBr, (4) silylamine, a compound having an Si--N bond, and the like.

(5) Sl-0R organoalkoxy (or alloxy) silane.

(6) Compound organosilanols having Si-0H bond (7) Compound containing Si-Si bond (8) Compound organosiloxane containing Si-0-Si bond.

(9) Organosilicon compound ester: An ester thought to be formed from silanol and acid, (CH3)2S
1(0C0CH3)2, etc. belong to this category.

(S)Organosilicon compound peroxide; (CH3)3Siα
℃゜(CH3)3,(CH3)3Si00Si(CH3
)3 etc.

In the molecular structures of (1) to (sub) above, R represents an alkyl group or an aryl group. The starting material (1) above
In order to produce an organosilicon polymer compound whose main skeleton components are silicon and carbon from organosilicon compounds belonging to the classification types (1) to (1) above, organic silicon compounds belonging to the classification types (1) to (1) must be used The compound is subjected to a polycondensation reaction using at least one of irradiation, heating, and addition of a polycondensation catalyst. Examples of the skeletal structures of organosilicon polymer compounds obtained from the organosilicon compounds (1) to (self) by the polycondensation reaction described above are as follows.

“.

-ni: }V busy niri 7 rin 2,. ．． 9,, n = 2, poly(ethylene oxysiloxane) (b) n;: - Enylene siloxane) n = ゛1, polygmethyleneoxysiloxane) n = 2, poly(ethyleneoxysiloxane) n = 6,
Poly(phenyleneoxysiloxane) n-Al2,,ri(diphenyleneoxysiloxane)(c)-Sinn=
1, lysylmethylene n = 2, polysylethylene n = 3, polysyltrimethylene n = 6, polysylphenylene n = 12, polysyldiphenylene (d) the skeleton components described in (a) to (c) above Those containing at least one partial structure among chain, cyclic and three-dimensional structures, and mixtures of f(X暉→).

The organosilicon polymer compound produced in this way is
It can be obtained as a viscous liquid or a solid at room temperature. Furthermore, in the present invention, if necessary, 0.1 to 20% by weight of an organometallic compound as described below is added to the organosilicon compounds of (1) to (to) above, and polycondensation is performed to form a metal-containing organometallic compound. It can also be made into a silicon polymer compound and used as a binder.

As the organometallic compound, those shown in Table 2 below can be advantageously used. After mixing 0.1 to 20% by weight of the organometallic compound with the organosilicon compounds of (1) to (sub) above, a polycondensation reaction is performed to produce an organosilicon polymer compound containing various metal elements as trace components in the skeleton. can be manufactured.

The main skeleton components are carbon and silicon as described above,
An organosilicon polymer compound containing a metal element in its skeleton as a trace component if necessary can be obtained as a solid or a viscous liquid at room temperature by a relatively simple and inexpensive manufacturing method.

In the present invention, these solids or viscous liquids can be used as they are as a binder. That is, these binders become liquids with low viscosity when heated at a relatively low temperature of around 300°C, so they are added to and mixed with a base consisting of a mixture of a heat-resistant inorganic silicon compound and metal silicon powder. At the initial stage when the green compact is heated and fired, it becomes a low-viscosity fluid and the organic matter containing hydrogen and silicon evaporates as volatile components, but the remaining carbon and silicon remain at a temperature of approximately 800°C.
From the above, the mixture gradually forms β-SiC, which begins to fill the gaps between the inorganic silicon compound powder and the silicon powder together with a small amount of remaining free carbon. The temperature further rises to 10
When the temperature reaches 00° C. or higher, the free carbon and metal silicon powder react to gradually generate SiC. Another 1250
When the temperature exceeds ℃, the grain boundaries of the inorganic silicon compound powder are occupied only by β-SiC of 5000 Å or less, which is converted and produced from the organosilicon polymer compound, and β-SiC, which is 100 It771 or less, which is produced by reaction from free carbon and metal silicon powder. It becomes like this. In other words, the excess material that existed at the beginning of heating either scatters and disappears, or it completely covers the inorganic silicon compound powder and silicon powder in the SiC base, and it is necessary to generate it during the subsequent heating process to a high temperature. Because it facilitates reactions and diffusion, it is an extremely advantageous binder that is extremely effective in producing a final, strongly bonded fired molded product. The chemical changes that occur during the heating process in the compacted body made of the above-mentioned starting materials will be explained below. As described above, the binder becomes a low viscosity fluid at the initial stage of heating and completely covers the inorganic silicon compound powder and the metallic silicon powder. As the heating temperature increases further,
The organosilicon polymer compound that is the binder is thermally decomposed, and mainly β-SiC and free carbon are produced and remain, while the others are volatilized. In such a heating process, the inorganic silicon compound powder particles are strongly bonded by the bonds between the powder particles and the bonds by β-SlC, but the β-SiC present at the grain boundaries is Since growth is inhibited, intragranular pores, which are normally formed during grain growth, are hardly present in the molded article of the present invention. In addition, the β-SiC present in grain boundaries, which is converted from organosilicon polymer compounds, is 1
When heated at 500° C. or lower, the particles usually exist as aggregates of particles with a diameter of 30 to 500 λ, so that the grain boundary region itself becomes a relatively low-density structure. However, the mechanical strength of the above-mentioned fine particle aggregates is extremely excellent due to the stress propagation relaxation mechanism unique to such aggregates, so even if the structure has a relatively low density, there will be no damage to the entire compact. This is a preferable form because it has the effect of improving thermal shock resistance without causing any adverse effects. In addition, SiC produced by reaction from metallic silicon and free carbon has a very small amount of metallic silicon and free carbon, so it is produced in an extremely small amount compared to the conversion-produced β-SiC described above, but the size of the particles is small. depends on the particle size of the metallic silicon powder added in advance. The smaller the particle size is, the easier the reaction with free carbon will be, which is advantageous; however, the generated SiC itself is surrounded by SiC fine particle aggregates converted from the above-mentioned organosilicon polymer compound, forming a strong bond. , mechanical strength is not adversely affected. Therefore, the particle size of metal silicon powder is 10μ
m or less is most preferable, but 101tm or more10
Even those down to 0 μm can be used advantageously. In addition, if the amount of metal silicon powder added is such that the molecular weight ratio to the amount of free carbon is close to 1:1, the amount of unreacted silicon or carbon remaining in the molded product will be reduced, and high strength molding at high temperatures will be possible. It is advantageous because it becomes the body. However, the amount of free carbon varies depending on the type of organosilicon polymer compound, heating and firing conditions, etc., but usually the amount of free carbon is 100%.
01) and remains at a ratio of 0.2 to 20% by weight. Therefore, the amount of the metal silicon powder added is determined based on the amount, type, firing conditions, etc. of the organosilicon polymer compound added as a binder. Since the silicon polymer compound is added in an amount of 0.05 to 20% by weight relative to the raw material powder, the amount of metal silicon added is 0.0% to the total weight.
It will be carried out in a range of 0.01 to 8% by weight. In the present invention, the binder made of the organosilicon polymer compound is added to the inorganic silicon compound and the silicon powder, usually at 0%.
．． Add and mix in a range of 0.05 to 20% by weight.

The amount added varies depending on the firing method as described below, but if it is less than 0.05(f), the effect of addition is poor and it is difficult to obtain a molded product with strong bonding and high strength, and if it is more than 20(f) So,
Since the ratio of the β-SiC phase, which is converted from the binder and occupies the grain boundaries, to the whole becomes considerably large, the relatively low-density structure becomes too large, which actually reduces the strength of the entire compact. Moreover, it is difficult to obtain a molded article that takes advantage of the characteristics of the base inorganic silicon compound. In order to perform pressurization and firing, roughly speaking, the mixed powder particles of the starting raw material are pressed into a single powder by a powder compaction method such as die press, isostatic press, extrusion, etc.
00~50001<g/(pressurized at a pressure of 1-J mo Vf,
After forming the powder into a predetermined shape, the powder is fired by a heating method using, for example, a resistance heating furnace or a high frequency furnace. Add grains and add 100 to 500
It is possible to use a hot press method in which pressing and firing of the powder are performed simultaneously while pressing the powder to 01<g/Cril.

As the atmosphere for the above-mentioned firing, an atmosphere consisting of at least one selected from vacuum, inert gas, CO gas, hydrogen gas, and organosilicon compound gas is used.

Further, the firing is performed at a temperature ranging from 1000°C to 1800°C, although it varies depending on the type of inorganic silicon compound.
However, it is advantageous to select and set the above-mentioned firing conditions so that they do not cause any disadvantageous alterations to the base inorganic silicon compound, metal silicon powder, or organosilicon polymer compound. It is advantageous to select a heating temperature below the melting point of the silicon compound, an atmosphere that does not create other compounds by reaction with these compounds, and the like. In the present invention, the firing temperature is more preferably within the range of 1200 to 1500°C.

The SiO converted from the organosilicon polymer compound is strongly bonded to the inorganic silicon compound powder during the heating process, and this bonding strength gradually increases during the heating process up to 1500°C, but when heated at a temperature higher than 1500°C, In this case, the bonding force does not increase so much, and a molded article with sufficiently high strength can already be obtained with the bonding force generated by heating up to 1500°C. Thus, one of the features of the present invention is that the suitable heating temperature in the method of the present invention is lower than the temperature at which ordinary heat-resistant silicon compounds are fired. By subjecting the thus obtained fired molded product to the following treatments, a high strength fired molded product having higher density can be obtained.

10]! Under reduced pressure of 1H9 or less, impregnate with the organosilicon polymer compound in liquid form or the organosilicon polymer compound to which a small amount of the silicon metal fine powder is added if necessary, and further pressurize if necessary to increase the degree of impregnation. After that, a series of treatments of heating in a temperature range of 1000°C to 1800°C in at least one atmosphere selected from inert gas, hydrogen gas, and CO gas in a vacuum is performed at least once. Therefore, a fired molded product with higher density can be obtained.
The organosilicon polymer compound to be impregnated needs to be in liquid form, so if these compounds are obtained in liquid form, they can be obtained as is, or if they are obtained in solid form, they can be heated at a relatively low temperature to turn them into liquid form. Can be impregnated. Alternatively, to reduce viscosity, a small amount of benzene, toluene, xylene, hexane, ether, tetrahydrofuran, dioxane, chloroform, methylene chloride, petroleum ether, petroleum benzine, ligroin,
Freon, DMSO, . It is possible to use a solution obtained by dissolving DMFl or other organosilicon polymer compound using a solvent. By repeating the above-mentioned series of treatments at least once, it is possible to obtain a fired molded product with a sufficiently high density even when firing at a temperature relatively lower than the usual firing temperature. The molded body obtained by repeating the above-mentioned impregnation and firing can have a higher density as the number of times of the above-mentioned treatment increases.

As mentioned above, before the impregnation treatment, the fired body has its grain boundaries filled with SiO fine particle aggregates with a relatively low density structure, but this is because the base silicon compound has not grown coarsely. Grain boundaries exist continuously from the surface to the inside of the compact. The impregnating liquid infiltrates into the low-density part of this continuous grain boundary and changes to β-SiC by heating. Therefore, by repeating the impregnation and heat treatment, the low-density grain boundary gradually becomes densified. Along with this, the bonding force between the base ceramic particles and the β-SiC at the grain boundaries becomes stronger, so the more times the impregnation and heat treatment are repeated, the higher the density and strength of the molded product can be obtained.However,
After the compact approaches approximately the theoretical density, the effect of repeating the above treatment becomes less pronounced. Further, if necessary, a small amount of metal silicon powder mixed in advance may be impregnated in order to react with carbon liberated from the impregnated organosilicon polymer compound. The metal silicon powder preferably has a particle size as small as possible. As described above, according to the manufacturing method of the present invention, since the organosilicon polymer compound can be impregnated, a molded article having high density and high strength can be obtained without using a hot pressing method, which is advantageous. Next, the present invention will be explained with reference to examples.

Example 1 Dodecamethylcyclohexasilane was placed in an autoclave and heat treated at 450° C. for 30 hours in an Ar atmosphere to obtain solid polycarbosilane.

The average molecular weight of this polycarbosilane was 1,700. SiC powder with a purity of 99.5% or more and 800 meshes or less and the above polycarbosilane with a weight ratio of 10 (:f) and about 1.4 weight of Si powder with a purity of 99.99 (:f) or more and 800 meshes or less. After adding % and kneading thoroughly, use a mold press to make approximately 2500k9/(1-JMo V1).
A prismatic pressurized body of 10×10×40 md was manufactured. This pressurized body was placed in an Ar atmosphere of 1 atm for 13
The sample was heated to 00° C. at a heating rate of C/Hr and held for 1 hour to obtain a fired molded body. S! is a conventional product with almost the same porosity as this molded body! Table 4 shows a comparison of properties with the 3N4 bonded SiC molded body. From the above table, it can be seen that the transverse rupture strength of the product of the present invention is significantly higher than that of the conventional product, and its high-temperature properties are also extremely excellent.

When the structure of this material was observed using a scanning electron microscope, it was found that the SiC particles of the base were 10
The diameter was ~25 μm, no coarsely grown grains were observed, and almost no pores were observed within the grains. Furthermore, silicon powder and free carbon react to form 1ψ-Sl at the grain boundaries.
It was found that there were C grains and β-type microcrystalline SiC of 5000 A or less having a low-density structure converted from polycarbosilane, and these formed a tight bond with the base SiC. Also, the presence of free carbon was not detected. As in this example, when SiC is used as the base, the molded body contains SiC
Since it is possible to obtain a high-purity SiC molded body in which only SiC is present and no other impurities are present, the molded body manufactured by the present invention can be used as a material with excellent high-temperature strength, and can also be used as a high-purity SiC molded body without any other impurities. It is a new material that can be expected to be used as a product in the electronic industry. Example 2 Five parts by weight of Si fine powder with a particle size of 2 μm or less was added to the pulverized polycarbosilane used in Example 1,
The mixture was placed in an autoclave together with the fired compact obtained in Example 1.

After reducing the pressure to 10-2 m1H9, it was heated to about 350°C and held for 1 hour, and then ArlOO air pressure was added and the pressure was increased to 30°C.
Impregnation treatment was performed by holding for a minute. The impregnated molded body was taken out, heated to 1300° C. over 8 hours in an Ar atmosphere, and held for 1 hour to obtain a new post-impregnated heat-treated molded body. The density of this material was -2.959/CTd, reaching 91.6% of the theoretical density. This material was further impregnated with polycarbosilane and heat treated under the same conditions as above. Such post-impregnation heat treatment was repeated a total of 5 times,
Table 5 shows the density and transverse rupture strength measured each time.
4 As is clear from the above table, the density and strength increase as the number of times the post-impregnation heat treatment is repeated.

When the temperature dependence of the transverse rupture strength was measured for the molded product obtained by applying heat treatment five times after impregnation, it was found that the temperature dependence of the transverse rupture strength was
It shows a constant value of 38.4 kg/M7l up to 150°C.
35.7kg/m1 at 0℃! , 31. at 1600℃.
6kg/7n21! It was found that this molded product also has excellent high-temperature strength. As in this example, by repeating impregnation with an organosilicon polymer compound and heat treatment, a molded article having a relatively high density can be easily obtained. Example 3 A solid polycarbosilane obtained from dimethyldichlorosilane was prepared with a purity of 99.501) and an Sl of 800 mesh or less.
2t0 was added to the mixture of 3N4 powder and Si powder with a purity of 99.99 (f) and a particle size of 5 μm or less.
Pressed with n/Cril mold, 10×10×
A 407nd pressure body was used.

The weight percentages of polycarbosilane and Si powder in the pressurized body were adjusted to be 7.0% and 1.0 (:fl), respectively.

This pressurized body was heated to 1300℃ in an Ar atmosphere of 1 atm.
20 was heated at a temperature increase rate of C/Hr and held for 1 hour to obtain a fired molded body. Table 6 shows the properties of this product and those of a conventional Si3N4 hot press molded product.

As shown in Table 6, the molded body according to the present invention is different from the conventional Si3
Compared to N4-MgO hot press molded products, the strength from room temperature to about 1000℃ is slightly inferior, but at 1000℃
In contrast, the molded product has higher strength, and this high strength is maintained up to a high temperature of 15000C or higher.

This high property is due to the fact that this molded product contains Mg, which is contained in conventional products.
This is due to the fact that it does not contain a glassy phase such as SiO3, which causes a decrease in strength at high temperatures, and only a phase consisting of mainly Si3N4 and other microcrystalline SiC is present. Therefore, this molded article is a new high-strength heat-resistant material that can be used up to at least 1500°C. Example 4 A mixture consisting of about 93% by weight of polysilane and about 7% by weight of dicarbonyl siftadiene molybdenum (MOC, OHl2O2) was reacted in an autoclave at 450°C for 24 hours to form a solid containing about 3% by weight of the MO element. A polycarbosilane was obtained.

Metal S with a purity of 99.9901) and a particle size of 1 μm or less is added to a powder of 800 mesh or less of MOSi2 with a purity of 99.5%.
After adding 5% by weight of polycarbosilane containing the above MO element to a mixture obtained by adding i powder (0.5 # by weight ratio) and kneading, the mixture was placed in a graphite hot press mold, and 1
After applying a pressure of approximately 300k9/Cd in an Ar atmosphere at atmospheric pressure for 5 hours until the temperature reached 1400°C,
After holding for 30 minutes, a hot press molded product having a diameter of 15 mm and a size of 5 Lm1 L was obtained. The properties of this product and those of the conventional product for comparison are shown in Table 7. In general, silicides of transition metals have superior oxidation resistance compared to carbides or borides, but their thermal shock resistance is several orders of magnitude lower, which limits their use as heat-resistant materials. The molded body in which the grain boundaries of MOSi2 were densely filled with β-SiC was heated at 1200°C.
The average number of times the molded product was water quenched to break was more than 20 times, which was 9 times for the conventional molded body made only of MOSi2, and it was found that the thermal shock resistance was significantly improved.
In addition, this molded product has excellent properties in terms of oxidation resistance, wear resistance, and corrosion resistance, so it can be used not only as a resistance heating element material or crucible material for which conventional MOSi2 has been used, but also as a variety of structural materials. It is a new material that can be used in a wide range of applications. In addition, in the above examples, a series of typical heat-resistant inorganic silicon compound fired compacts and their manufacturing methods are shown, but other heat-resistant inorganic silicon compounds can also be used to produce similarly excellent high-strength fired products. It can be made into a molded body.

As described above, according to the present invention, a high-strength fired molded product is obtained by using an organosilicon polymer compound whose main skeleton components are silicon and carbon as a binder in a base silicon compound to which metal silicon powder is added. Furthermore, by impregnating this material with the organosilicon compound and firing it, a high-density and high-strength fired molded body can be obtained.Such fired molded bodies are used in the aerospace industry, Metal metallurgy industry, ship and automobile industry, petrochemical industry,
It can be expected that it will be extremely effectively used in the ceramics industry, electronics industry, electrochemical industry, nuclear industry, and other various fields where high-strength, heat-resistant molded material is required.

[Brief explanation of the drawing]

The figure is a scanning electron micrograph of the fired compact of the present invention.

Claims (1)

[Claims] 1. A mixture obtained by adding and mixing an organosilicon polymer compound whose main skeleton components are carbon and silicon to a mixture of heat-resistant inorganic silicon compound powder and metal silicon powder. Processing and forming the mixture in vacuum, in an atmosphere consisting of at least one selected from inert gas, CO gas, hydrogen gas, and organic compound gas within a temperature range of 1000 to 1800°C. The grain boundaries of each particle of the powder body are substantially densely filled with the following two types of SiC particles (a) and (b), and the high-temperature strength is obtained by heating and firing the body. A method for producing a heat-resistant inorganic silicon compound sintered compact. (a) 5000 produced from organosilicon polymer compounds
β-SiC fine particles of Å or less. (b) 100 μm produced by reaction between metal silicon powder and free carbon produced from the organosilicon polymer compound.
The following β-SiC particles. 2 Processing and molding a mixture obtained by adding and mixing an organosilicon polymer compound whose main skeleton components are carbon and silicon to a mixture of heat-resistant inorganic silicon compound powder and metal silicon powder, and , a step of heating and firing the processed molded product of the mixture within a temperature range of 1000 to 1800°C in an atmosphere consisting of at least one selected from inert gas, CO gas, hydrogen gas, and organic compound gas. After impregnating the fired molded body produced by the method with the organosilicon polymer compound or an organosilicon polymer compound mixed with metal silicon fine powder, the fired molded body is heated in vacuum with an inert gas, C.
1000 to 1800 in an atmosphere consisting of at least one selected from O gas, hydrogen gas, and organic compound gas.
The grain boundaries of the particles of the fired compact obtained by applying the series of impregnation and heating processes once or twice or more within the temperature range of ℃ are substantially of the following two types (a) and (b). SiC
A method for producing a heat-resistant inorganic silicon compound fired molded body densely filled with particles. (a) 5000 produced from organosilicon polymer compounds
β-SiC fine particles of Å or less. (b) 100 μm produced by reaction between metal silicon powder and free carbon produced from the organosilicon polymer compound.
The following β-SiC particles.