JPS5973480A - Manufacture of silicon carbide/glassy carbon composite poro-us body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a silicon carbide/glassy carbon composite porous body.

Silicon carbide has high strength at high temperatures and is excellent in corrosion resistance and oxidation resistance, and its sintered body is attracting attention as a high temperature corrosion resistant material and a structural material. Various methods such as gas phase reaction method, reaction sintering method, and hot press method have been studied as methods for manufacturing silicon carbide sintered bodies with properties similar to those of silicon carbide. At present, it is difficult to obtain it easily. Furthermore, since silicon carbide has high strength and is hard, post-processing of the sintered body is difficult, and this is also a major factor preventing the expansion of its uses.

Glassy carbon also has high strength and corrosion resistance, but the cutting method has the disadvantage of large weight loss and deformation during firing and poor productivity, so it is desirable to consider more efficient manufacturing methods. ing.

Further, as a material suitable for applications requiring excellent heat insulation properties and resistance to corrosive fluids, a porous body having an appropriate porosity with a small pore diameter is desired.

The present inventors have completed the present invention as a result of intensive research in view of the above-mentioned problems of existing methods. Silicon carbide/
The present invention provides a method for producing a glassy carbon composite porous body. Other objects and advantages of the present invention will become apparent from the following description.

Achieved by the method for producing a lath-like carbon composite porous body〇Silicon carbide fine powder used in the present invention includes α-810, β
-8iO may be used, and the particle size is α1 to 100μ.
It is possible to use something of about 0.5m, especially 0.5~
Preferably, the thermosetting resin has a diameter in the range of 50 μm.0 As the thermosetting resin used in the present invention, phenolic resin
．． Furan resin, melamine resin, area resin, epoxy 4
Examples include attrium fat and unsaturated polyester resin, and these may be used alone or in combination.

Among the thermosetting resins mentioned above, phenolic resins and furan resins are particularly preferred because they have a high carbonization yield through thermal decomposition in a non-oxidizing atmosphere, and phenolic resins are most suitable in terms of ease of handling during resin curing operations. Reed, then furan resin is suitable O Phenol resin expansion, resol resin and novolac tree m2f
Resole resins, which are divided into Ti compounds, are the initial products produced by reacting phenols with aldehydes in the presence of basic catalysts, and are usually self-containing molecules with a short length of up to about 600, which are rich in methylol groups. It is a thermally crosslinkable resin. Especially 1.5~ per mole of phenol! h, 5
The water-soluble resol obtained by reacting a mole of aldehydes in the presence of a slightly excess alkali catalyst and maintaining the initial condensate in a stable water-soluble state is easy to handle and can be used in the present invention. It is the most desirable thermosetting resin to be used.

Phenols used in the production of resol resins most commonly include phenol and cresol. However, other phenols can also be used, such as phenol, 0-cresol, m-cresol, p-cresol, 2.3-xylenol, 2.5-xylenol, 2,4- Xylenol, 2.6-xylenol, 4-xylenol 1. !
1.5-xylenol, 0-ethylphenol, m-ethylphenol, p-ethylphenol, p-phenylphenol, p-tert-furfural, I) -t
Examples include art-aminophenol, bisphenol A, resol 7nol, and mixtures of these phenols.Formaldehyde is the most common aldehyde used for polycondensation with these phenols. However, monoaldehydes and dialdehydes such as paraforno aldehyde, hexamethylenetetramine, furfural and glutarj'aldehyde, azibaldehyde and glyoxal may also be used.

Basic catalysts used in the resol resin synthesis reaction include caustic alkali, alkali carbonate, barium hydroxide, hydroxide, ammonia, quaternary ammonium compounds,
Known amines may be used, and caustic soda or ammonia is most commonly used.

The novolac resin is prepared by combining the same phenols used in the production of the resol resin and the same aldehydes used in the production of the resol resin with oxalic acid,
Manufactured by reaction with heating in the presence of an acidic catalyst such as organic acids such as formic acid, acetic acid, halogenated acid, and pantoluenesulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid, and cynic acid. Molecule iI#: 300-20
It is an uncured and meltable thermoplastic resin with a strength of about 0.00.

Furan W fat toshi is furfuryl alcohol resin, furfuryl alcohol phenol m Jll, Fu”fu 7-
For example, organic acids such as aniline hydrochloride and paratoluenesulfonic acid can be used as curing agents for these resins.

Area resin and melamine resin are initial condensates of urea-formaldehyde and melamine-formaldehyde, respectively, and are water-soluble and therefore easy to handle. Stiff,
As curing agents, inorganic acids such as hydrochloric acid and sulfuric acid, carbo/acid esters such as dimethyl oxalate, and amine hydrochlorides such as ethylamine hydrochloride and triethanolamine hydrochloride can be used. .

A liquid bisphenol type epoxy 4mM& obtained by reacting in the presence of can be used. The epoxy resin may be used by diluting it to an appropriate concentration with a solvent such as methanol, toluene, or xylene, and adding amines, organic acids, or the like as a curing agent.

As the pore-forming material used in the present invention, starch or other organic fine powder, or fine powder of a sublimable compound, etc. can be used. The type and size of the powder may be appropriately selected depending on the pore diameter of the intended porous body.

The silicon carbide/glassy carbon composite porous material of the present invention is mixed, if necessary, a curing agent is added to perform a curing reaction, and then washed,
It may be fired at 800° C. or higher in a non-oxidizing atmosphere.

Phenol resins such as resol resins or novolak resins, such as methanol and acetone, are preferably used as water-soluble resols because they are easy to handle. In the case of resol resin, a small amount of organic acid such as para-toluenesulfonic acid or phthalic acid may be added in advance to the above solution as an acid catalyst for curing, if necessary.6 In the case of novolak resin, methanol, acetone, etc. A crosslinking agent may be further dissolved in a solution of a predetermined concentration obtained by dissolving an appropriate amount in a solvent such as the above.

As the crosslinking agent, hexamethylenetetramine is most commonly used, but aldehydes such as nimoparaformaldehyde, glutaraldehyde, azibaldehyde and glyoxal, and acids or alkalis may also be used in combination.

In the case of a 7-run resin, the furan resin is dissolved in a solvent such as acetone or benzene, and a solution containing a curing agent such as aniline hydrochloride or paratoluenesulfonic acid in an amount of about 0.2 to 1% of the solid content of the resin is prepared. All you have to do is get involved.

In the case of area resin or melamine resin, a solution prepared by mixing several percent of an acid catalyst or the like as a curing agent into an aqueous solution of the resin may be used.

Furthermore, it is desirable to use epoxy resin, unsaturated polyester resin, etc. in combination with phenol resin, furan resin, etc., considering the carbonization yield during firing.

As mentioned above, silicon carbide fine powder and pore-forming material are added to thermosetting hatsumode of a predetermined concentration dissolved in a solvent, stirred and mixed, transferred to a mold of a desired shape and heated to complete the curing reaction, Remove the molded product from the mold and wash it with water.

The shape of the molded product can be a plate, a cylinder, or any other shape that can be freely selected depending on the purpose, use, and required performance.

The silicon carbide/thermosetting resin porous body of the present invention is fired at a temperature of at least 800°C in a non-oxidizing atmosphere, that is, under reduced pressure, or in an inert gas such as arbon gas or helium gas, hydrogen gas, nitrogen gas, etc. Preferably, heating is performed at 1000°C or higher.

The silicon carbide content in the silicon carbide/glassy carbon composite porous body obtained as described above is usually 60 to 90% by weight, preferably 65 to 853i-ji5A.

Most preferably 70 to 80 ◇ Also, the porosity of the silicon carbide/vitreous carbon composite porous material is usually 40 to 80% by weight.
, preferably 4.5 to 70% by weight.

In producing the silicon carbide/glassy carbon porous body,
If the silicon carbide content is too low, weight loss and deformation during firing will be large, and production efficiency and raw product yield υ will decrease. If it is too high, the strength of the composite porous body due to the weak bond between the silicon carbide fine powder and the glassy carbon is undesirably lowered.

The porosity of the silicon carbide/glass-like carbon composite porous material varies depending on the ratio of silicon carbide and thermosetting resin solid content to the solvent and the amount of pore-forming material. The porosity decreases as the amount increases, and the porosity increases as the amount of solvent and the amount of pore-forming material increase. If the porosity of the silicon carbide/glassy carbon composite porous material is too high, the strength will decrease significantly;
And the insulation property decreases No. 匨匍1≦;IF) [=.

In addition, if the porosity is too low, the inner cone is used to uniformly mix the raw materials, which may be difficult to work with during production.1.
A good silicon carbide/vitreous element extraction porous body cannot be obtained.

The pore diameter of the silicon carbide/glassy carbon porous material obtained by the present invention is generally distributed in the range of 0.1 to 50 μm, particularly 0.5 μm.
Most of the pores have a diameter of about 10 μm'. The silicon carbide/vitreous carbon composite porous body has extremely good corrosion resistance and heat insulation properties, and is suitable as a high-temperature heat insulating material, a shield for corrosive fluids, and a jig for an electric furnace.

In addition to the above-mentioned uses, the silicon carbide/glass-like carbon porous material has
It can also be used as a lightweight structural material, abrasive material, heating element, and heat treatment jig.

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

Example 1 A water-soluble resol resin solution with a solid content concentration of 65% (Sumitomo Dehyoroshizu ■ product, Sumilite Resin PR961A) e Heated a predetermined amount and when the temperature reached 60°C, it was heated to 70°C in advance.
Add 200 y of wheat starch gelatinized at ℃ and stir at 70 to 80 ℃ for 15 minutes while stirring. After cooling this solution to 40 ℃, add a predetermined amount of β-silicon carbide fine powder with an average particle size of 2 μm and mix thoroughly. The mixture was stirred and mixed, and further, 20% by weight of para-toluene sulfonic acid was added as a curing agent based on the water-soluble resol resin, and the mixture was stirred.

The mixed solution was poured into a cylindrical mold, heated at 80°C for 24 hours to perform a curing reaction, and then removed from the mold and heated in the shower for 8 hours.
After washing for several hours to wash away the acid catalyst, etc., dry the
A silicon carbide/phenol resin composite porous body measuring 50 m"×60 was obtained.

The composite porous body obtained as described above was placed in an electric furnace, the temperature was raised at 20°C/hr in a nitrogen atmosphere, and the temperature was maintained at 1000°C for 1 hour to sinter the silicon carbide/glassy carbon composite porous body. I got it.

Table 1 shows the charged composition of the silicon carbide/vitreous carbon composite porous body, changes in weight and volume due to firing, and properties of the obtained silicon carbide/vitreous carbon composite porous body.

In Table 1, S in the silicon carbide/glassy carbon composite porous material
The iO content is 48
It was determined by measuring the weight of silicon carbide after burning the glassy carbon for a certain period of time.

In addition, the corrosion resistance of the silicon carbide/vitreous carbon composite porous material is
In o2/H2o mixed atmosphere (002 flow rate 517mln)
, retention rate at 950°C, retention rate at 950°C, and retention rate at 950°C. As can be seen from the table a, the silicon carbide content of the silicon carbide/glassy carbon composite porous material is 60~
At 90% by weight, a porous body with good workability and good sample condition during production and excellent corrosion resistance was obtained.

Table 1 Example 2 Furan resin solution with solid content concentration of 50% by weight (Hitachi Chemical ■ product, Hitafuran 302) IC average particle size 0.5μ
Add a predetermined amount of α-silicon carbide fine powder of m and stir thoroughly.
Furthermore, a predetermined amount of potato starch was added and mixed while being careful not to cause agglomeration.

A curing agent for hitafuran corresponding to 0.2% of the furan resin was added to this mixed solution, and the 1r-0 nucleus crystal mixture diluted with acetone was further poured into a rectangular mold, so that the total liquid volume was 52%. The curing reaction was carried out by holding at 70°C for 48 hours, and after removing the mold, it was washed with a shower for 8 hours and dried to form a silicon ash of 500' x 2001 x 201.
A furan resin composite porous body was obtained. The composite porous body was heated at 10°C to 800°C in an argon atmosphere.
/hr After that, the temperature was raised at 50℃/h, r to 1500℃.
C. for 1 hour and fired to obtain a silicon carbide/glassy carbon composite porous body.

The preparation composition and characteristics of the above glassy carbon composite porous material were determined in the second step.
Shown in the table.

As shown in Table 2, a good silicon carbide/glassy carbon composite porous body was obtained with a porosity in the range of 40 to 80z.

Table 2 Example 6 In the same manner as in Example 1, 400 p of a water-soluble resol resin solution (Sumitomo Delez ■ product, Sumilite Resin PR961A) with a solid content concentration of 65% by weight was prepared.

Water-bathable melamine resin solution with a solid content concentration of 60% (Sumitomo Chemical ■ product, Sumitex Resin M3, curing catalyst, Sumitex AcX) 200 J/, β with an average particle size of 10 μm
-8iC fine powder 8009 and wheat starch 30g were mixed,
Furthermore, water was added to adjust the total position of the mixed liquid to 1Q.

The mixed liquid was cast into a flat formwork to create a + o o
"〆'bX 200" x 4 mt (7') & shape 9
Synthesis hole f, 20°C/hr in hemium atmosphere
The temperature was raised to 700° C., 900° C., and 1500° C. at a temperature increasing rate of 100° C., and held at each temperature for 1 hour to create a silicon carbide/glass-like carbon composite porous body. The silicon carbide/vitreous carbon composite porous body was immersed in a mixed solution of concentrated nitric acid/concentrated hydrochloric acid=/1 (volume ratio) at 90° C. for 7 days. The results are shown in Table 5. From Table 3, it can be seen that when the firing temperature is 800° C. or higher, the obtained silicon carbide/glassy carbon composite porous body has excellent chemical resistance.

Table 3

Claims (1)

[Scope of Claims] (1) A silicon carbide/glass-like product characterized by mixing fine silicon carbide powder and a thermosetting resin solution together with a pore-forming material, and firing the mixture in a non-oxidizing atmosphere after a curing reaction treatment. Manufacturing method of carbon composite porous body (2) Silicon carbide 'Jg/glass according to claim (1), wherein the silicon carbide content in the silicon carbide/glassy carbon composite porous body is 60 to 90% by weight. A method for manufacturing a carbon composite porous material. (6) The method for producing a silicon carbide/vitreous carbon composite porous body according to claim (1), wherein the silicon carbide/vitreous carbon composite porous body has a porosity of 40 to 80%. (4) The method for producing a silicon carbide/glass-like carbon composite porous body according to claim (1), wherein the M curable resin is a phenol resin or a furan resin. (5) A method for producing a silicon carbide composite porous body according to claim (1), which comprises firing at a temperature of 800° C. or higher in a non-oxidizing atmosphere.