JPS5848504B2 - Shutoshite SIC Yolinal Silicon carbide construction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a SiC sintered body.

The present invention was first invented and patented by the present inventors in JP-A No. 5
No. 2-40509 and JP-A No. 52-58720, which have higher strength and excellent oxidation resistance at high temperatures than the silicon carbide sintered molded bodies invented by the present inventors. The purpose of this is to provide a method for producing a silicon carbide sintered body mainly made of SiC, and the organosilicon compound used as a binder in the method previously invented by the present inventors, or the organosilicon compound A mixture formed by adding and mixing a small amount of an organometallic compound, a metal complex, and at least one or more selected from organic polymers other than the above two types of compounds to an organosilicon polymer compound obtained by polycondensation, or Mainly SiC produced by adding and combining one or two compounds as a binder and firing.
Because metal nitrides, oxides, borides, carbides, or free carbon are dispersed in the structure of the silicon carbide sintered compact, it has high strength, low porosity, and good oxidation resistance at high temperatures. SiC with small grain size
This objective can be achieved by obtaining a silicon carbide sintered compact having a

The organosilicon compounds that can be used as the binder are as follows.

(1) Compounds containing only Si--C bonds This includes compounds called silahydrocarbons, such as R4Ss+R3Si(R'SiR)R'SiR2, and their carbon-n functional derivatives.

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

(10) Organosilicon compound peroxide: (CH3)3S1
00C・(CH3)3, (CH3)3S too
i(CH3)3 etc.

In the molecular structures (1) to 3 above, R represents an alkyl group or an aryl group.

In the present invention, an organosilicon polymer compound having silicon and carbon as main skeleton components, for example, a compound having the following molecular structure, is produced from the raw materials.

(d) A substance containing the skeletal components described in (a) to (c) above as at least one partial structure of a chain or three-dimensional structure, or a mixture of (a x mouth p →).

Examples of compounds having the above molecular structure include the following.

(d) Those containing the skeleton components described in (1') to (c) above as at least one partial structure among a chain, cyclic, and three-dimensional structure, or (i) (a mixture of orifices).

In the method of the present invention, the starting materials (1) to (1)
In order to generate an organosilicon polymer compound having silicon and carbon as main skeleton components from an organosilicon compound belonging to the classification type 0), the organosilicon compound belonging to the classification type 0) to α0) is irradiated. A polycondensation reaction is carried out using at least one of the following: , heating, and addition of a polycondensation catalyst.

In the method of the present invention, the organosilicon compounds belonging to the above (1) to (10) are irradiated as they are or by a known method,
At least one selected from an organometallic compound, a metal complex, and an organic polymer other than the above two types of compounds is added to an organosilicon polymer compound subjected to a polycondensation reaction using at least one of heating and addition of a polycondensation catalyst. A mixture obtained by adding and mixing two or more species, or a compound obtained by heating and melting one or two of the compounds obtained by adding and combining them can be used as the binder.

When an organosilicon compound belonging to the above (1) to (IO) is mixed with SiC powder as a binder, molded, and fired, the compound is thermally decomposed, and the hydrogen, chlorine, or some carbon therein is volatilized and remains. The temperature of carbon and silicon is approximately 1,250℃
The above combines to form SiC.

Next, organometallic compounds, metal complexes, and organic polymers other than the above two types that can be used in the present invention will be explained below.

First, as the organometallic compound, for example, compounds (A) to (D) can be used.

(A) Structural formula (R n SiR '4, V2
) An organosilicon compound containing a Si-0-Si bond represented by y can be used.

Here, each R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a monovalent halogenated hydrocarbon group; The organosilicone compound is a block copolymer consisting of a hydrogen ether group or a divalent halogenated arylene group, n is 1 or 2, and y is a block having a structural formula having an average value of at least 5.

(B) In the reaction between a halogenosilane and a compound having one or more NH2 or NH groups, 20 to 200
It is possible to use organosilicon compounds with Si--N bonds which are obtained as easily crosslinked liquid or resinous products at temperatures of .degree.

The halogenosilane has the general formula R n S = x4-
(wherein R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a monovalent halogenated hydrocarbon group, X is F, Ct, Br or I, and n is 0,
1, 2 or 3).

For example, R is preferably a C, to C6 group, and in particular, dimethyldichlorosilane, methyldichlorosilane, ethyltrichlorosilane, diethyldichlorosilane, vinyltrichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, phenyldichlorosilane, diphenylchlorosilane, etc. are used. It is advantageous to do so.

(C) Boron-containing organometallic compounds as represented by the general formula B n C 2 H n + 2 can be used.

Here, n is 3 to 10, for example, carboranes 2,3
- dicarbar crossaw undecaporan (2, 3-
B9C2H,, ), dicarbar closodecaporan (B8C2H1o), and the like.

(D) Organometallic compounds having the following ligands (A) and (CI) can be used.

(a) Hydrocarbon alkyl and aryl derivatives, hydrocarbon acyl derivatives, α-alkenyl derivatives, σ-cyclopentadienyl derivatives, halogenated hydrocarbons, alkyl and aryl derivatives, acetylide or alkynyl derivatives,
Fluorine, chlorine, bromine, iodine.

(0) Ethylene, propene, cyclohexene, cis-cyclooctene, carbon monoxide, norbornadiene, styrene, stilbene, acrylonitrile, acrylate, acrylic ester, butadiene, cyclopentadiene,
Cyclohexa-1,3-diene, cycloocta-1,5-diene, cyclohexa-1,4-diene, hexa-1,5-diene, dicyclopentadiene, dimethyldivinylsilane,
cyclododeca1,5,9-triene, cyclohepta1,
3,5-triene, cyclohepta-1,5-diene, cycloocta-1,3,5-triene, acetylene derivative, penta-1,3-diene, cyclooctatetraene, π-cyclopentadienyl derivative, substituted benzene derivative .

The following can be used as the central metal atom of the organometallic compound having the above-mentioned ligand.

Group IVB of the periodic table (titanium, zirconium, hafnium), Group 8 (vanadium, niobium, tantalum) and Group VI (chromium, molybdenum, tungsten), lanthanide group (cerium, praseodium, neodymium, samarium, europium, gadolinium) , terbium, disprosium, small rhomium, erbium,
These include metals such as thulium and ytterbium, aluminum, and metals constituting metal nitrides, oxides, borides, and carbides having high melting points as shown in Tables 1 to 4.

Further, as the metal complex, for example, the following compounds can be used.

Hexaammine cobalt (n) chloride, chloroacotetraammine cobalt (III) nitrate, trinitratriammine cobalt (IID1 trioxalate (III)
), potassium hexacyanoferrate(n), metal β-monoketoenolates shown below, or metal chelate complexes obtained using various chelating agents can be used.

The metal β-ketoenolate is represented by the following general formula.

Here, n is 2 to 4, R1 is a hydrogen atom, an alkyl group, a phenyl group, fluorine, chlorine, bromine, and iodine, and the alkyl group is preferably 1
having ~16 carbon chains, R2 and R3 can be independently selected, an alkyl group, a halogen-substituted alkyl,
Aryl, for example, in the above structural formula, R1, R2, R
3 is methyl, trifluoromethyl, ethyl, proyl,
Isoprovil, heptafluoroprobil, butyl, tertiary butyl, pentyl, heptyl, octyl, dodecyl,
Hexadecyl, phenyl, biphenyl, phenoyl, naphthyl, and naphthoyl.

The above chelating agents include ethylenediamine, propylenediamine, 1,3-diaminopropane, 2,2'-bipyridyl, glycine, diethylenetriamine, iminodiacetic acid, triethylenetetraamine, dil-IJ lotriacetic acid, ethylenediaminetetraacetic acid, 8-hydroxy Quinoline derivatives (e.g. 8-hydroxyquinoline, 5,7-dihalo-8-hydroxyquinoline, 5,7-dinitro-8-
hydroxyquinoline, 5-nitrone-8-hydroxyquinolides, 2-methyl-8-hydroxyquinoline, 4-methyl-8-hydroxyquinoline, etc.), 8-mercaptoquinoline, oxime derivatives (e.g. dimethylcrioxime, α-furyldi Oxime, α-penzyldioxime, salicylaldoxime, α-penduin oxime, etc., dithiocarbamate derivatives, xanthate derivatives, dithiol derivatives, nitronarylhydrocydylamine derivatives, N-benzuyl, N-phenylhydroxylamine dithizone derivatives Metal chelate compounds including the like can be used.

As the central metal ion of the metal chelate compound, those listed in Table 5 below can be used.

Moreover, organic polymers other than the above-mentioned organometallic compounds and metal complexes can be used.

Vinyl polymers, vinyl copolymers, diolefin polymers, polyethers, polythioethers, polyesters, polyamides and polypeptides can be used as organic polymers.

Polyethylene oxide, polyisobutylene, polymethyl methacrylate, polyisoprene and polystyrene can be used with particular advantage.

According to the method of the present invention, an organosilicon compound or an organosilicon polymer compound, an organometallic compound, a metal complex,
When at least one organic compound other than the seed compound is added, a mixture and/or compound is formed.

The compounds produced at this time include the compounds shown in (a) and (g) below.

(B) For example, SI-co(CO)4, Si-Co(Co)4 + Si-co(C
O)2 ("{' 5H5) tSI-+'e(C
A material having a direct bond between a silicon atom and a metal atom having O)2(7r-C5H5) or the like as a partial structure can be used.

(mouth) For example, S i -( 7r-C 5}{5)F
e (7r-{', H5)? Si-(π-C5H4
) An organosilicon polymer compound containing an organometallic compound to which silicon atoms are bonded and has CO (Co)2 or the like as a partial structure can be used.

In the present invention, at least one selected from an organometallic compound, a metal complex, and an organic polymer other than the above two compounds is added to the organosilicon polymer compound, and a mixture obtained by mixing is used as a binder. When fired, the various types of microcrystalline metal nitrides, oxides, borides, carbides, or free carbon are uniformly and finely dispersed in the structure of the silicon carbide sintered compact, and the silicon carbide, which was previously invented by the present inventors, is This results in a silicon carbide sintered body that has less porosity than a sintered body, has high strength, and has high oxidation resistance at high temperatures.

In the present invention, it is advantageous to add additives to the organosilicon compound or organosilicon polymer compound in a range of 0.1 to 30%.

The reason why it is advantageous to add the additive in an amount of 0.1 to 30% is that if it is less than 0.1%, the above-mentioned various compounds of metals or Since the amount of free carbon available is small and it is not possible to obtain the desired sintered compact with high strength, and if it exceeds 30%, the density gradually decreases, so it is advantageous to set the content to 0.1 to 30%. .

As for the SiC powder that can be used in the method of the present invention, if very high purity is not required depending on the use of the SiC sintered compact, commercially available SiC powder can be used.

In addition, in order to obtain SiC powder with relatively high purity, high-purity silica stone, such as SI02 min 99.8% or more, and carbon with an ash content of 0.3% or less, such as petroleum coke or retort carbon, are used. can be made into SiC powder6
.

In addition, it is advantageous to use SiC powder obtained by firing high-purity carbon such as sugar carbon or carbon black and high-purity metal silicon at 1250° C. or higher.

Moreover, SiC powder obtained by a gas phase decomposition method can also be used.

Among the binders of the present invention, polyluposilane, which can be advantageously used because it is an organosilicon compound that is easy to produce and exhibits the least weight loss after burning, will be described below.

Polycarbosilane is a liquid or solid, as it is or, if necessary, in a solvent such as benzene, toluene, xylene, hexane, ether, tetrahydrofuran, dioxane, chloroform, methylene chloride, petroleum ether, petroleum benzene, ligroline, DMSO, DMF. ，
In addition, polyrubosilane is dissolved in a solvent that can dissolve polyrubosilane, and a small amount of at least one selected from organic metal compounds, metal complexes, and organic polymers other than the above two types of compounds is added, A mixture of one or two types can be made into a viscous liquid and used as a binder when producing a SiC sintered body.

In addition, binders other than polyrubosilane that can be used in the present invention can also be used in accordance with the embodiment in which polyrubosilane is used.

In the present invention, the binder is usually added to the SiC powder at 0%.
．． Add and knead in a range of 3 to 30%.

The amount added may be the amount necessary to pressurize and self-sinter the SiC powder, and the amount added can be adjusted by the method of forming and sintering as described below.

The kneaded mixture is molded into a molded article having a predetermined shape.

Note that it is also possible to use a true press method in which the material is heated in a mold and pressure molded during the sintering process.

In order to sinter the molded body, in a vacuum, an inert gas, CO
A silicon carbide sintered body can be obtained by sintering in an atmosphere of at least one selected from gas and hydrogen gas in a temperature range of 1000°C to 2200°C.

If the above firing is performed in air, the binder will be oxidized and the SI
O2, so it is advantageous to perform the firing in vacuum or in at least one atmosphere selected from inert gas, CO gas, and hydrogen gas.

In addition, using the hot press, in a vacuum under a pressure of 70 to 20,000 Ky/crA, in an atmosphere of at least one selected from inert gas, CO gas, and hydrogen gas. By doing this, the conversion rate of the binder to SiC can be increased, and more dense S
It can be an iC sintered compact.

In addition, when performing heating in a vacuum, if the temperature is heated for a sufficient period of time, the conversion rate of the binder to SiC will be improved and the shrinkage of the molded product will be uniform, resulting in a dense molded product. be able to.

However, oxidizing gas, nitriding gas,
One or more of the hydrocarbon gases is 10wIlHg
Even if it exists at a partial pressure below, there is no problem in carrying out the above-mentioned sintering.

The hot press method used in the present invention is one of the methods of sintering powder of refractory material, in which the powder is heated in a mold without being shaped in advance, and pressure molding is performed during the sintering process to form particles. This method improves clogging and obtains a dense molded base.

In the industrially practiced high-temperature pressing method, the temperature is iooo
The most common range is ~2200°C, pressure 140~70 OKi.

Furnace heating methods generally employ electrical heating, of which there are two types: resistance heating, which is the most common, and high-frequency induction heating, which is the second most common.

In resistance heating, an induction voltage regulator that continuously changes the voltage from O to 30 volts and has a current of 15,000 amps is widely used, and such resistance graphite tubes for heating have a wall thickness of 1.3 volts.
(1m, outer diameter 20CrrL1 length 150α) is used.

High frequency induction heating uses a wide frequency range of 1000 to 30000 cycles per second.

The molded body has a diameter of 2. 15 in 30,000 cycles for small-scale high-temperature presses up to 5 cm, length 2,5 crrL
kva is appropriate, diameter 35 cIrL1 length 25 (
In the case of a large size up to about 1'771, 1000 cycles and 300 kva are appropriate.

The simplest pressurization method is the lever type, but since it is inconvenient to adjust the pressure, a hydraulic or pneumatic ram type can be advantageously used.

If the mold is electrically conductive at 1000-2200°C, which is suitable for pressing, it is preferable to use graphite, since it can be directly heated by resistance or induction methods.

To explain in detail the process of SiC self-sintering when manufacturing the SiC sintered compact according to the present invention, the organosilicon compound and its polymer used as a binder are thermally decomposed during the heat treatment process, and excess carbon and hydrogen are removed. It evaporates as a volatile component, and the remaining carbon and silicon combine to form SiC, which forms a strong bond with the externally added SiC powder.

In this process, if the temperature is slowly increased over a sufficiently long period of time, the grain boundaries of the added SiC powder will be filled with organosilicon compounds and their polymers, which will gradually combine to form SiC and become self-contained. It plays a role in supporting the self-sintering properties of SiC, which has slow diffusion.

Furthermore, when the binder used in the present invention is converted into SiC, it forms SiC microcrystals, and the crystal grain size is usually 30 to 70 mm.
It is considered that the SiC sintered body is significantly smaller than the SiC sintered body, and therefore has a significantly large surface area, and the apparent self-diffusion coefficient of SiC is extremely large. This will increase the sinterability, resulting in a dense self-sintered compact.

The reason why these ultrafine silicon carbide particles are produced is that at least one kind selected from an organometallic compound, a metal complex, and an organic polymer other than the above two types of compounds is added to an organosilicon compound or an organosilicon polymer compound. ,
In the process of thermal decomposition of one or two of the binders in the mixture, the various microcrystalline metal nitrides, oxides, borides, carbides, or Free carbon is uniformly and finely dispersed,
At the same time, it is thought that this is to suppress the coarsening of silicon carbide microcrystals, which are mainly used for survival.

It is thus believed that metal oxides, carbides, nitrides, borides, or free carbon play an important role in obtaining the various effects described above.

It is further advantageous to use metals in the form of chemically stable metal oxides, carbides, nitrides, and borides having relatively high melting points as shown in Tables 1-4.

The metal elements constituting the metal compound suitable for use in the method of the present invention include group IVB of the periodic table (titanium, zirconium,
Hafnium), Group B (vanadium, niobium, tantalum) and Group VIB (chromium, molybdenum, tungsten), Lanthanide group (cerium, praseodium, neodium, samarium, europium, gadolinium, terbium, disprosium, holomium, erbium, thulium, It is a metal element belonging to the phylogenetic group (itterbium, lutetium), and other metal elements such as boron, aluminum, or the above metal oxides, carbides, nitrides,
These include metals that form borides.

According to the present invention, a sintered body with even higher density can be obtained by subjecting the SiC sintered body thus obtained to the series of treatments described below at least once or more.

That is, first, the sintered body is immersed in a liquid of an organosilicon compound to impregnate the grain boundaries and pores of the sintered body with the solution.

When performing this immersion treatment, it is advantageous to place the sintered body in a vacuum container in advance and immerse it in the solution under reduced pressure, since this allows the solution to permeate deep into the sintered body.

Furthermore, the impregnation treatment can also be carried out under high pressure.

Next, by heating and firing the impregnated sintered body in a temperature range of 1000 to 1700°C, a high-density sintered body can be obtained.

In the present invention, it is preferable that the organosilicon compound used for the impregnation be deeply penetrated into the inside of the sintered compact, and when impregnating a viscous organosilicon compound, it is dissolved using a solvent that can dissolve this compound. It is advantageous to immerse the sintered shaped body in a solution in which the sintered body is heated.

The impregnated organosilicon compound is converted to SiC by heating.

This SiC exists in the grain boundaries and pores of the base sintered body, and due to mutual diffusion between this SiC and the sintered body and diffusion of free carbon that normally remains due to heating of the organosilicon compound, this SiC and the sintered body are separated. Form a strong bond.

The degree of pressure reduction is 10 ffl}I! It is advantageous for the above-mentioned high density to be lower than i'.

The organosilicon compounds are the same as those that can be used as the binder mentioned above, but in order to facilitate impregnation, solvents that can dissolve them, such as toehabenzene, toluene, xylene, hexane, etc. Ether, tetrahydrofuran, dioxane, chloroform, methylene chloride, ligroin, petroleum ether, petroleum benzine, D
It can be dissolved using MSO, DMF, etc. and used as a less viscous solution.

However, if the organosilicon compound can be sufficiently impregnated as it is, there is no need to use the solvent to form a solution.

The heat treatment is carried out at a temperature range of 1000 to 1700°C, and the atmosphere includes vacuum, air, oxygen gas, inert gas, CO gas, hydrogen gas, hydrocarbon gas,
One or more selected from ozone can be used.

However, when heating in an oxidizing atmosphere among the above atmospheres, in order to prevent oxidation of the impregnated organosilicon compound, heat the temperature in advance from room temperature to approximately 1000°C in a non-oxidizing atmosphere.
It is advantageous for high purity to preheat the impregnated organosilicon compound to an inorganic substance mainly composed of SiC.

Furthermore, the above-described series of densification treatments can be repeatedly carried out in each visit as long as impregnation is possible.

Next, the SiC sintered compact thus obtained may contain free carbon that normally remains when an organosilicon compound is converted to SiC, and this free carbon acts as an impurity and reduces the strength of the sintered compact. may invite

This free carbon is removed by heating the sintered body in an atmosphere of at least one selected from oxygen gas, air, ozone, and hydrocarbon gas, preferably at a temperature in the range of 600 to 1700°C. be able to.

Carbon cannot be removed sufficiently even if the calcination is performed at a temperature of 600°C or lower, and if the temperature exceeds 1700°C, the reaction between SiC and the atmospheric gas becomes significant, so it is preferable to remove free carbon at a temperature higher than this temperature. do not have.

The firing time in the above atmosphere varies depending on the firing temperature, the size of the compact, and the structure of the firing furnace.If the firing temperature is low, it will be necessary to fire for a long time, and if the firing temperature is high, the firing time will be shortened. It may be shorter, but if anything, better results can be obtained by firing at a lower temperature for a relatively long time because the amount of reaction products between SiC and atmospheric gas produced is smaller. When the crucible is fired in air at 1000°C to remove free carbon, 0.1 to 3 hours is appropriate.

In the present invention, the amount of binder added is preferably within the range of 0.3 to 30% (if the amount added is less than 0.3%, it is difficult to obtain a SiC sintered body; If the amount is too large, the bulk specific gravity will decrease, the strength will decrease, and the oxidation resistance will decrease when used at high temperatures. Therefore, it is advantageous to keep the amount within the range of 0.3 to 30%, and the hot press method In the case of the SiC sintering method obtained in this way, the best results can be obtained with an additive amount of 1 to 5%, and in the case of a method of press forming and then firing, an additive amount of 5 to 15%. The shape is determined first because the binder used will eventually convert into microcrystals of SiC, metal oxides, carbides, nitrides, borides, or free carbon, and to suppress the coarsening of the silicon carbide microcrystals that are mainly produced. Si obtained by the method of the present inventors
Compared to C sintered compacts, it is possible to obtain products with high strength and high oxidation resistance at high temperatures.

Next, the present invention will be explained with reference to examples.

Example 1 Dodecamethylsilane was placed in an autoclave and heat treated at 400°C for 36 hours in an argon atmosphere.
A liquid polysilane was obtained.

The average molecular weight of this polycarbosilane was 1,800.

To obtain silazane, a type of organometallic compound, 200 Elr of ammonia was added to a solution of 51 g of methyltrichlorosilane and 100 gr of methylene chloride at 40° C. under pressure.

Furthermore, when the ammonium chloride produced by the reaction is concentrated, it becomes a silazane solution of 30,? r obtained.

Average 600 mesh purity 99.90% SiC powder 30
5g of the above polysilane and 0.5g of silazane liquid
After thoroughly kneading the mixture, it is press-molded into a crucible shape, and
-'7taH,! i' in vacuum from room temperature to 1,500℃
It was fired for 8 hours until the temperature reached 8 hours, and a SiC crucible was prepared.

The bulk specific gravity of the silicon carbide crucible was 2.96.

Next, a mixture of 20 cc of the liquid polycarbosilane and 2 cc of silazane liquid was dissolved in 10 cc of toluene to form a solution, and then IX 1 0-3aH, ? The SiC sintering crucible kept in a vacuum was impregnated with the solution.

The impregnated crucible was heated to 1500° C. over 8 hours in an argon atmosphere and held for 1 hour to form a new sintered body.

The bulk specific gravity of the obtained crucible sintered body was 3.07.

This material was further impregnated with the solution and heated once each under the same conditions as above, and the bulk specific gravity of the obtained sintered material was 3.12.

When this material was further subjected to the series of impregnation and heat treatments described above, the bulk specific gravity of the obtained sintered material was 3.17.

By repeatedly subjecting the sintered body thus obtained to a series of treatments, including the impregnation process with an organosilicon compound and the heating process, the bulk specific gravity gradually approached the theoretical specific gravity, making it possible to obtain a dense sintered body. .

When the obtained sintered body was observed using a scanning electron microscope, it was found that microcrystals of Sl3N4 and SiC and a small amount of free carbon were deposited in the porous pores of the SiC sintered body.

This is due to the fact that the binder silazane contains nitrogen, causing S to thermal decomposition.
This is a product of the nitride of i.

When the crucible thus obtained was used to melt silicon metal, it had a significantly longer lifespan than conventional crucibles and was sufficiently durable for use at high temperatures.

Example 2 Chain dimethylpolysilane 10.9 synthesized from dimethyldichlorosilane was placed in an autoclave and heated in an argon atmosphere at 400°C and a pressure of 30 atmospheres for 30 hours.

6.3 g of polycarbosilane was obtained as a reaction product.

The average molecular weight of this product was 1,500.

50 g of SiC powder with an average of 450 mesh and a purity of 99.75% produced from metallic silicon and carbon was mixed with 5 g of the above-mentioned polysulfosilane and tris (2,2,6,
6-tetramethyl-3,5-heptanedionato) P
knead 0.3 g of the mixture as a binder, put it in a graphite mold to form it into a nozzle shape, and use a hot press to knead it in a vacuum (1 x 10 -'HllH
&) 2 0 0 Ky/cr? 1800℃ under pressure of t
The temperature was gradually increased over a period of 10 hours by high frequency transmission heating method.

This is a dense SiC nozzle with a bulk specific gravity of 3.16.

Furthermore, 10 g of the above polysilane and Tris (2,
2,6,6tetramethyl-3,5-heptanedionato)
After dissolving the mixture of P r (IID O. 1 .!i' in petroleum benzine IOcC to form a solution, 1 x 1
The solution was poured into the SiC nozzle which was kept in a vacuum of 0-3 vm to impregnate it.

After this impregnation, the nozzle was heated to 1,000°C in an argon atmosphere.
The mixture was heated for 5 hours and held for 2 hours.

Further, this product was heated in air to 1400° C. over 8 hours and held for 1 hour to obtain a new nozzle sintered body.

The bulk specific gravity of the obtained nozzle sintered body was 3.17.

When the obtained sintered compact was observed with a scanning electron microscope, it was found that fine crystals of SiC, Pr4C3 and free carbon were
It was observed that C was deposited in the porous pores of the sintered C shape.

The carbide is formed because praseodymium (Pr) is contained in the organometallic compound of the binder.

In this way, the sintered body impregnated with an organosilicon compound is first heated to about 1000°C in a non-oxidizing atmosphere, and then heated in the temperature range of 600 to 1700°C in an oxidizing atmosphere to form a SiC sintered body. The densification treatment and the liberated carbon treatment can be performed simultaneously.

Ribbon-shaped silicon metal was manufactured using the thus obtained nozzle.

Comparing this to nozzles manufactured using conventional methods, the lifespan is longer.

Example 3 10g of linear dimethylborisilane synthesized from dimethyldimethylborosilane was placed in an autoclave and heated in an argon atmosphere at 400°C and a pressure of 30 atm for 30 hours to obtain 6.3g of polycarbosilane as a reaction product. .

The average molecular weight of this product was 1,500.

A mixture of 8 g of the above polycarbosilane and 2 g of titanocene C (C5H5)2T ict2) dissolved in 30 ml of xylene was mixed with SiC powder 50& as binder 11, heated and molded into a rod shape, and the xylene was removed under reduced pressure. , from room temperature to 1500°C in an argon atmosphere 12
The temperature was raised over time.

This product had a bulk specific gravity of 3.03.

Properties such as mechanical strength of this material are shown in Table 7.

As is clear from the table, various properties of the product of this example are significantly improved compared to the conventional SiC sintered body bonded with si3N4.

When the obtained sintered compact was observed using a scanning electron microscope, it was found that fine crystals of TiC and SiC and a small amount of free carbon were precipitated and dispersed.

This is because titanium is contained in the titanocene binder, so carbides of Ti and carbides of Si are produced.

Further, when this material was subjected to impregnation and heat treatment similar to those in Example 2, the bulk specific gravity was 3.12, and various mechanical strengths and oxidation resistance were also improved.

Furthermore, when this rod-shaped sintered body was used as a heating element, the lifespan was approximately 30% longer than that of a conventional SiC heating element.

Example 4 1,3-disilacyclobutane was placed in an autoclave and heated at 350°C for 40 hours in an argon atmosphere to obtain a solid organosilicon polymer compound.

The average molecular weight of this product was 150,000.

50 g of SiC powder and 0 of the above organosilicon polymer compound powder
．． 1 and 0.1. 2, which is a type of organometallic compound of Fr.
3-Dicarbar crossaw undecafolane (2,3
-B, C2H,, ) as a binder, put it in a graphite mold, and heated it in an argon gas atmosphere using a hot press.
Under pressure of 00K2/cTL, the temperature was gradually raised to 1600° C. over 12 hours by high frequency induction heating and held for 30 minutes.

This is a dense, rod-shaped S with a density of 3.13 (.9/i)
It was an iC sintered body.

When the obtained sintered compact was observed using a scanning electron microscope, it was found that fine crystal carbides of B4C and S+C and a small amount of free carbon were precipitated and dispersed.

This is because the binder (2,3-dicarbar chloroundecaborane) contains boron, so B forms a carbide.

Further, the relationship between the density of a sintered body obtained by a method similar to that of this example and the temperature of the real press is shown in the figure as Invention 1.

For comparison, β-SiC-}-1%Fe+1%At
The same figure also shows the relationship between temperature and density when hot pressing 203 and α-Si'C+1%A403.

As is clear from the figure, the density of the sintered compact according to the present invention increases earlier at low temperatures than that of the comparative example, and further approaches the theoretical density at high temperatures.

In addition, a series of densification treatments including impregnation and heating were repeated twice each on the homopress sintered body obtained in this example using a method similar to that described in Example 2.

However, the heating temperature was the same as the hot press temperature.

The relationship between the density of the impregnated sintered body obtained at each temperature and the heating temperature is shown in the figure as Invention 2.

As is clear from the figure, by performing the densification treatment, a higher density sintered body can be obtained at a lower heating temperature.

Example 5 Dodecamethylsilane was placed in an autoclave and heat treated at 400°C for 36 hours in an argon atmosphere.
A liquid organosilicon polymer was obtained. This organosilicon polymer was dissolved in n-hexane, and acetone was added to this solution to obtain a solid organosilicon polymer insoluble in acetone.

The average molecular weight of this product was 3,200.

0.6 g of the acetone-insoluble solid organosilicon polymer powder was added to 50.9 g of commercially available average 320 mesosh SiC powder.
and dicobalt octacarbonyl [CO2(CO)8]0
．． 1g as a binder, and in order to mold it into a pipe shape, put it in a graphite mold and use a hot press in a vacuum (1 x 10-'tttxHj9), 7
0 0 Kp/i (7) Under pressure, the temperature was gradually raised to 1750° C. over 12 hours using a high-frequency induction heating doctor.

The SjC sintered body obtained in this way has a bulk specific gravity of 3
．． 14 dense SjC tubular bodies.

When the obtained sintered compact was observed using a scanning electron microscope, it was observed that carbides of CoC and SiC were precipitated and dispersed.

This is due to the binder dicobalt octocarbonyl [Co2(
Co in CO)8] and Si in hexasilane form carbide.

Further, when this SiC tubular body was impregnated with polycarbosilane and heat treated once in the same manner as described in Example 1, the specific gravity became 3.17.

When this SiC tubular body was used in a zinc distillation vessel, its life was significantly extended compared to conventional products.

Example 6 Octafenyl tetrasilane was placed in an autoclave and heated at 400°C for 20 hours in an argon atmosphere.
A solid organosilicon polymer was obtained.

50 g of 400 mesh 99.5% purity SiC powder, 0.5 g of the solid organosilicon polymer and boristyrene O. I. ! The mixture i' was mixed as a binder, placed in a graphite mold to form a nozzle shape, and heated under a pressure of 5t/i in an argon gas atmosphere using a hot press to form a nozzle.
The temperature was gradually raised to 0°C over 12 hours by high frequency induction heating.

The SiC sintered body thus obtained has a bulk specific gravity of 3.
19 SiC nozzles.

When the obtained sintered compact was observed using a scanning electron microscope, it was found that fine crystals of SiC were precipitated and dispersed.

This is because Si in the silane in the binder forms carbide.

Furthermore, when this nozzle was impregnated with polycarbosilane and heat treated once in the same manner as described in Example 1, the bulk specific gravity was 3.195, almost reaching the theoretical density.

Using this nozzle, we were able to produce high-purity metallic silicon.

As described above, according to the present invention, a dense sintered body with good oxidation resistance can be obtained.

[Brief explanation of the drawing]

The figure shows the relationship between the density and sintering temperature of a sintered body made of a mixture of SiC powder and a binder by hot pressing, and the relationship between the density and sintering temperature of a sintered body made of a mixture of SiC powder and a binder, and the sintered body obtained by subjecting the sintered body to a series of treatments of impregnation with an organosilicon compound and heating. FIG. 3 is a diagram showing the relationship between the density and heating temperature of a high-density molded body.

Claims (1)

[Claims] 1. The following organosilicon compounds: (1) Compounds containing only Si--C bonds, (2)
Compounds containing Si-H bonds in addition to Si-C bonds, (3) Compounds having Si-Hat bonds, (
4) Compounds having Si-Si bonds, (5) Compounds having Si-N bonds, (6) Si
-OR (R-alkyl, aryl) bond-containing compound, (7) S i -OH bond-containing compound, (8)
A compound containing a Si-0-Si bond, (9) an organosilicon compound ester, (IO) an organosilicon compound peroxide, or an organosilicon compound consisting of one or more of the following: Addition of catalyst for polycondensation from organosilicon compounds, irradiation, heating failure or at least 1
Organosilicon polymer compounds whose main skeleton components are silicon and carbon, which are produced by polycondensation reactions, are mixed with small amounts of organometallic compounds, metal complexes, and organic polymers other than the above two types of compounds. A step of molding a mixture mixed with SiC powder using one or two of the mixtures obtained by adding and mixing at least one selected from the following as a binder;
In vacuum, in at least one non-oxidizing atmosphere selected from inert gas, CO gas, and hydrogen gas 10
1. A method for producing a silicon carbide sintered body mainly made of SiC, the method comprising the step of heating at 00°C to 2200°C. 2. In the specified invention, the resulting silicon carbide sintered body mainly made of SiC is impregnated with a solution of the same kind as the binder, and then heated in a vacuum with an inert gas, CO gas, hydrogen gas, or hydrocarbon gas. heating at 1000° C. to 1700° C. in at least one non-oxidizing atmosphere;
A method for producing a sintered silicon carbide shaped body mainly made of SiC, characterized in that the step of heat treatment at a temperature of 1700° C. to 1700° C. is repeated at least once or more than once.