JPH0142915B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a molded sintered body made of non-oxide ceramics such as carbides, nitrides, silicon compounds, borides, metals, or composites of metals and non-oxides, and which has improved heat resistance and oxidation resistance. Regarding the manufacturing method. [Prior Art] The present inventors previously published Japanese Patent Application No. 55-89988 (Japanese Unexamined Patent Publication No.
57-16029), the main chain skeleton is as follows (A),
Mainly composed of structural units (B), (C), (D), (E) and (F), The structural units form chain, branched, and cyclic structures, and furthermore, there are

[Problem that the invention seeks to solve]

The present invention is characterized by the fact that this organosilicon polymer is soluble in organic solvents such as n-hexane, xylene, tetrahydrofuran, benzene, etc., like conventional polycarbosilants, and has heat softening properties that melt when heated at 60 to 300°C. substance, and also in a non-oxidizing atmosphere,
For example, nitrogen, argon, helium, ammonia,
We focused on producing silicon carbide containing graphite by heating it to 800℃ or higher in hydrogen or hydrocarbon gas, and developed it as an excellent impregnating agent and coating material for heat-resistant, oxidation-resistant refractories. It was completed by discovering that it imparts certain characteristics. 1 to 6 show charts of an infrared absorption spectrum, a far-infrared spectrum, and an ultraviolet absorption spectrum as characteristics of the organosilicon polymer used in the present invention. Figures 1 and 4 are charts showing infrared absorption spectra, at around 830 cm ^-1 and at 1250 cm ^-1 .
Absorption based on Si−CH ₃ and 1410, 2900, 2950
Absorption based on C-H at cm ^-1 and further at 2100 cm ^-1
Si-H shows absorption based on Si-CH ₂ -Si at 1030 and 1355 cm ^-1 . In the far-infrared absorption spectra shown in FIGS. 2 and 5, absorption in the far-infrared region of 450 to 300 cm ^-1 is based on Si-Si bonds, and 400 cm ^-1 ,
The absorption at 383 cm ^-1 and 362 cm ^-1 is unique to cyclic polysilane. Furthermore, in the ultraviolet absorption spectra shown in Figures 3 and 6, an absorption end occurs between 340 and 370 mm, and in the organosilicon skeleton, It can be seen that it contains a chain or cyclic polysilane moiety. When the number average molecular weight of the organosilicon polymer is 400 or less, when heat-treated at a predetermined temperature in a non-oxidizing atmosphere, there will be almost no residue, resulting in improved oxidation resistance and other properties. It is ineffective in terms of In addition, if the molecular weight exceeds 5000, it will contain undissolved components or be extremely poorly soluble in organic solvents such as xylene and THF, and will also contain giant polymers, making it difficult to impregnate into the pores of the shaped sintered body. Impregnation efficiency is poor and impractical. Therefore, the number average molecular weight of the organosilicon polymer used in the present invention is 400.
Must be ~5000. When the organosilicon polymer was heated at 1400°C for 1 hour in an argon stream, graphite was identified in addition to carbides by X-ray diffraction. Si), vanadium (V), boron (B), titanium (Ti), aluminum (Al), zirconium (Zr), hafnium (Hf), thorium (Th), niobium (Nb), molybdenum (Mo), Tungsten (W),
Metals containing these metal atoms and non-oxidized It has strong adhesion to physical ceramic sintered bodies. It also exhibits strong adhesion to clean SiC and carbon surfaces through chemical bonding.
It also shows chemical bonds with carbides other than silicides and SiC. Furthermore, although urides and borides do not show chemical bonds by commonly used sintering methods, silicon carbide containing graphite produced by thermally decomposing the organosilicon polymer is not damaged. , it can create a physical entanglement bond with nitrides and borides. The heat treatment temperature after coating is 800℃ in a non-oxidizing atmosphere.
It is necessary to carry out the test within the range of 2000℃. At temperatures below 800°C, organosilicon polymers are unstable and easily oxidized; at temperatures above 2000°C, their strength decreases due to crystal growth; and when combined with non-oxide ceramics, they may decompose or evaporate. This is undesirable, and when used in combination with a metal body, the metal body may melt. By repeating the coating, impregnation, and post-coating heat treatment as necessary,
A denser coating layer can be obtained. As described above, chemical bonding between the organosilicon polymer used in the present invention and the metal, carbide, silicide, or carbon, and nitrides and borides, can be achieved by heating the organosilicon polymer. Utilizing the bond created by physical entanglement with silicon carbide containing graphite, it is possible to form ceramics or ordinary Fe, Mo, Fe through methods such as impregnation and coating.
-It can be applied to metal sintered bodies such as Cu, and is extremely effective in improving the oxidation resistance and corrosion resistance of these shaped sintered bodies. Furthermore, in the present invention, not only the organosilicon polymer but also non-oxidized ceramics, metals or non-oxidized materials such as carbides, nitrides, silicon compounds, and borides are used from the viewpoint of chemical bonding, expansibility approximation, and integration. Ceramics and metal composite powder materials can be mixed and applied to enhance performance. Examples of the present invention will be described below. [Example] Example 1 2.5 g of anhydrous xylene and 400 g of sodium were placed in the three-necked flask of Example 1, and 1 dimethyldichlorosilane was added dropwise over 45 minutes while stirring. Prognosis at the end of instillation,
The mixture was heated under reflux for 10 hours to form a precipitate. This precipitate was filtered, first washed with methanol, then water, dried, and further washed with acetone and benzene to form a white powder.

380g of polysilane having the formula (n≧10) was obtained. To 100 g of this polysilane, 16.0 g of anhydrous aluminum halide AlCl ₃ was added and mixed, and the mixture was reacted for 8 hours under a nitrogen stream in a quartz tube equipped with a reflux tube. When the reaction was over, it was filtered as a xylene solution to remove impurities. After removal, it is distilled to 320℃ in a nitrogen atmosphere,
Xylene and low-boiling components were removed and concentrated to obtain an organosilicon polymer. The yield was 50.5 g, and the number average molecular weight was 4100. 70 parts by weight of the organosilicon polymer prepared above, solvent n-
A silicon nitride sintered body (200 x 100 x 20 mm) (1) obtained by reaction sintering was impregnated in a solution of 30 parts by weight of hexane and treated in a pressurized impregnation container at 10 atmospheres for 3 hours. was taken out and heated in air at 100°C for 5 hours to completely remove residual hexane and at the same time cross-link and infusible the organosilicon polymer, and then heated at 1450°C in a nitrogen stream.
It was heated and fired. Comparing the characteristics of the product that has undergone this operation once (2), the product that has been performed twice (3), and the product that has undergone this operation three times (4), (2) has stronger strength compared to (1). The oxidation resistance, decomposition resistance to molten iron, and erosion resistance to converter slag are increased, and those that have been treated many times also have increased properties. The results are summarized in Table 1.

[Table] Example 2 3.0 g of anhydrous gallium chloride GaCl ₃ was added and mixed to 100 g of the above-synthesized opolysilane and reacted for 16.5 hours in the same manner as in Example 1 to obtain 58.5 g of an organosilicon polymer with a number average molecular weight of 2050. Ta. A porous silicon carbide sintered body (φ25 x 100 mm) (5) used in commercially available heating elements, etc. is
The sample was immersed in a solution containing 30 parts by weight of xylene as a solvent, put into a rubber mold, impregnated under pressure for 3 minutes at a pressure of 500 kg/cm ² using an isostatic press, and then taken out and placed in the air. ,
Xylene was completely removed by leaving at room temperature and heating at 100°C for 5 hours, and then irradiated with an ultraviolet lamp with a relative intensity of 90% at 253.7 nm for 30 hours to crosslink and infusible the organosilicon polymer. in the air current
The mixture was heated and calcined at 1300°C to obtain (6). When (6) is heat-treated at 800°C or lower, the heated organosilicon polymer is in an unstable state and is easily oxidized. When (6) is heated above 2000℃, a decrease in strength due to crystal growth is observed. An organosilicon polymer containing a portion of siloxane bonds produced by reacting polysilane with phenyl group-containing polyborosoxane, which has already been disclosed in Japanese Patent Application No. 52-127630 (Japanese Unexamined Patent Publication No. 54-61299), is similarly impregnated into the same sample. Compared to (7), which was heat-treated in an oxidizing atmosphere, (6) showed even better oxidation resistance (1400°C) and corrosion resistance against molten pig iron at 1300°C. The test results are summarized in Table 2.

[Table] Example 3 The organosilicon polymer with a number average molecular weight of 4100 used in Example 1 was prepared using the method described in Example 2 to form a graphite electrode rod.
(8), impregnated into a graphite electrolytic plate (9), and then heated with Ar air flow.
After heat treatment at 1200℃ and then melt coating the same polymer on the surface of the treated object, it was heated to 1450℃ in an Ar gas flow.
heated to ℃. As a result of comparing the oxidation resistance of the treated product (8), (10) and (9) by heating in the air, the oxidation loss rate was 800℃ for 2 hours compared to the untreated product. Both showed 1/10 to 1/18, in the air
The oxidation loss rate at 1000°C was also 1/5 to 1/10. The above results are summarized in Table 3.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an excellent ceramic body with improved oxidation resistance, strength, and corrosion resistance, and is excellent for high-temperature parts such as engines, blades, nose cones, heat exchangers, sealing materials, packing materials, and bearings. It can manufacture wear-resistant parts such as materials, brake materials, parts that require corrosion resistance such as tanks, ducts, pipes, and valves, as well as other electrical materials, electronic materials, piezoelectric materials, and materials for nuclear power.

[Brief explanation of drawings]

The attached figure shows the properties of the organosilicon polymer used in the invention. 1, 2, and 3 show charts of infrared absorption spectrum, far-infrared spectrum, and infrared absorption spectrum of the organosilicon polymer produced in Example 1. FIG. 4, FIG. 5, and FIG. 6 show charts of infrared absorption spectrum, far-infrared absorption spectrum, and plasma radiation absorption spectrum of the organosilicon polymer produced in Example 2.

Claims (1)

[Scope of Claims] 1. On a shaped sintered body base made of non-oxide ceramics, metals, or composites of metals and non-oxide ceramics, the main chain skeletons are as follows (A), (B), ( Mainly composed of structural units C), (D), (E) and (F), The structural units form chain, branched, and cyclic structures, and furthermore, there are It has a polysilane skeleton of (2≦n≦10), has absorption in the far-infrared region of 450 to 300 cm ^-1 in the far-infrared absorption spectrum, and has an absorption end in the ultraviolet absorption spectrum of 340 to 370 nm. The average molecular weight is
400 to 5000, either alone or as a mixture of one or more of non-oxide ceramic powder, metal powder, or composite powder of metal and non-oxide semiconductor, to form a non-oxidation 1. A method for producing heat-resistant and oxidation-resistant ceramics, characterized by heat treatment in a temperature range of 800 to 2000°C in a neutral atmosphere.