JPS61247661A - Oxidation-resistant high strength carbon material - 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] <Field of application in industry> The present invention has excellent oxidation resistance and high strength, and is suitable for use in various mechanical parts materials, ceramic materials, chemical industry materials, electrical and electronic components. This invention relates to carbon-based materials that have a wide range of uses as materials.

<Prior art> Carbon-based materials have many properties such as high temperature strength, thermal shock resistance, high thermal conductivity, good electrical conductivity, and low thermal expansion. It has the disadvantage of being easily corrupted. For example, when a carbon-based material is heated in the atmosphere, it reaches 300°C.
Oxidation is occurring from nearby! J, when fi becomes 1 below 00℃, its oxidation 1,1 Bodhisattva 17 < progress -4 Otsu's -C 3. For that reason, use carbon-based materials with +l'N description -4, J1
Must be in an intoxicating atmosphere and 17, use 1''-C has major restrictions-) j, 7.

In order to improve the shortcoming of this carbon-based material, which is that it is highly oxidized and easily oxidized, various uninvented works have been published in Japanese Patent Application Laid-Open No. 591315.
Publication No. 7fi and Japanese Unexamined Patent Publication No. 592131't74'1!7
A carbon-ceramic composite key as shown in the publication was developed and t:5. The material shown in both publications is a sintered body of a powder mixture made by mixing boron carbide powder and silicon carbide powder with boron carbide powder and silicon carbide powder. It was confirmed that high-temperature oxidation of carbon-based materials can be significantly suppressed by adding L to the material.

<Problems to be solved by the invention> In the present invention, boron carbide and silicon carbide are blended into the raw coke disclosed in Japanese Patent Laid-Open No. 131576 (L-131576). Unexamined Japanese Patent Publication No. 59/1989, in which the sintered body and the blending ratio of boron carbide and nitrogen carbide were adjusted to a specific value.
-213Fi7H:) ll' of the sintered body shown in the publication
The aim is to further improve oxidation resistance at high frequencies.

<Means for Solving the Problems> In the present invention, a poride ceramic other than boron carbide is added as a fourth component to the raw coke-boron carbide-silicon carbide developed by the inventors as described above. The gist is that the total amount of boron carbide powder and silicon carbide powder is 5 to 50% by volume, and the balance is raw coke powder. This is an oxidation-resistant high-strength carbon material consisting of a sintered body of a powder mixture in which 1 to 20 weight percent of the amount is replaced with boride ceramics.

Note that the raw coke used in the present invention may be petroleum-based, coal-based, or resin-based, but it is preferably produced at a relatively low temperature of 600°C or less and has residual volatile content, so that a product with particularly high strength can be obtained. The residual volatile content is preferably 4% by weight or less. The raw coke powder to be used has a diameter of 25 μm or less, preferably 5 μm or less, and its volume ratio is preferably 50 to 95%.

Next, what is boron carbide powder and silicon carbide powder?
A fine powder of 7 zm or less, preferably 5 um or less is desirable, and in order to have sufficient solubilization resistance in high drought conditions near 1400°C, a cleavage arrangement in which silicon carbide has a larger appearance than boron carbide and 17 The weight ratio of boron carbide to silicon carbide is preferably 4951 to 298. That is, if the amount of silicon carbide is less than this range, the oxidation resistance at around 1400° C. will be poor, and if it is too much than the range B, the oxidation resistance will be poor. As a substitute for these boron carbide and silicon carbide, it is also possible to use substances that become boron carbide or silicon carbide during sintering, such as boron oxide or silicon oxide.

Next, as a poride as the fourth component, for example, human 18
2. TiB2. There are ZrB2, etc., and the boride ceramic powder (B) is a fine powder with a particle size of 25 μm or less, preferably 5 μm or less, and the blending amount is 1 to 20% by weight of the total amount of boron carbide and silicon carbide. Let it be the replaced amount. The reason for this is that when the amount of the boride ceramic is less than the range specified in 1, no particular effect can be seen in the improvement of oxidation resistance in the high temperature range, which is the effect of adding it, and the opposite is true. This is because if the temperature exceeds the range specified in 2 above, the high-temperature creep strength of the material itself decreases.

The method for manufacturing the oxidation-resistant high-strength carbon material of the present invention involves blending predetermined amounts of raw coke powder, boron carbide powder, silicon carbide powder, and boride ceramic powder, and thoroughly grinding the powder to form a caking process. After increasing the properties and sinterability,
A method of molding and sintering at a temperature of 1000° C. or higher in a non-oxidizing atmosphere is adopted. As shown in Part B, the present invention does not use additives such as binders that cause pores, but utilizes the mechanochemical effect produced by grinding to impart sinterability, resulting in a dense and high-strength product. Becomes the property of

<Examples and effects> The present invention will be explained in detail below based on examples thereof.

11 Takashi ↓ Raw petroleum coke produced at about 500℃ (volatile content about 10% by weight) is crushed in a vibrating ball mill for 1 hour, resulting in an apparent raw coke powder with a specific gravity of 1.35g/CT1t and an average particle size. SiC, B4C, Aj' B2. T
In; 7°Z r 82, the mixed powder was made into a blending ratio as shown in Table 1 below, and was ground in a mill for 5 hours, then molded at a pressure of 2 t/cur, and inert gas A sintered body was obtained by sintering in an atmosphere at 2000° C. for 1 hour. This sintered body was cut into a size of 7 x 7 x 5 mm, placed in an electric furnace pre-maintained at 1300°C, and air was blown at 217°C.
Figure 1 shows the oxidation loss measured by the method of introducing at a rate of 1.

For comparison, Figure 1 shows B4C7,2%-3i by weight.
The oxidation loss of the C-B4C-3iC-based material of C28, 4% by weight of residual coke is also shown.

Table 1 (weight%) The same raw coke powder as in Example 1 above, and SiC.

Using each powder of 84C and Human I R2, the weight ratio is 5iC.
B4C: A l 82 = 80.328.8110.
Results of measuring the interlayer spacing λ as an index of bending strength and degree of graphitization for sintered bodies obtained in the same manner as in Example 1 from mixtures of mixed powder 89 with various amounts of raw coke powder are shown in FIGS. 2 and 3.

For comparison, these figures 2 and 3 also show 84C7,
2% by weight - 5iC28, 4% by weight - C of residual coke
Data regarding B4C-3iC-based materials are also listed.

As is clear from the results of the above examples, C-B of the present invention
4C-5iC and AJ B2. TiB2. Zr8
As shown in Fig. 1, even if the material containing No. 2 boride is kept in the atmosphere at 1,300°C, it is only slightly oxidized, and the oxidation occurs within the first hour. It can be seen that the amount of oxidation does not increase even after the passage of time. This is a person IB2゜TiR2
This is thought to be due to the fact that the glassy film formed on the surface of the material in an oxidizing atmosphere has an extremely weak oxidation inhibiting effect at high temperatures.

Also, from FIGS. 2 and 3, it is clear that the material of the present invention has a conventional product
It can be seen that, compared to -84C-SiC, the degree of graphitization is greater and the bending strength is also significantly improved.

The Young's modulus and compactness of the material of the present invention were measured17.
As a result, it was confirmed that all of them were larger than the conventional product CB+C-5iC.

<Effects of the Invention> As described above, according to the present invention, the oxidation resistance at high temperatures is greater than that of the C-84C-5iC-based material previously developed by the present inventors, and the strength is also increased. It also has the effect of being high.

Therefore, the material of the present invention can fully exhibit various characteristics as a carbon-based material even in a high temperature range, so it can be used in many applications such as materials for various mechanical parts, materials for the ceramic industry, corrosion-resistant materials for the chemical industry, and materials for electrical and electronic parts. It can be used for.

[Brief explanation of drawings]

FIG. 1 is a graph showing the oxidation loss of the material of the present invention and the conventional material, FIG. 2 is a graph showing the bending strength of the material, and FIG. 3 is the interlaminar spacing pressure, which is an index of the degree of graphitization. Graph showing o2. Patent applicant: Director of the Agency of Industrial Science and Technology (1 other person) Sub-agent: Ariyoshi Kyoto rtsuho (y) zoop Liu Jingfu Kungun's bitter procedures rzanjF-2 book 11) May 1985 1711

Claims (1)

[Claims] 1. The total amount of boron carbide powder and silicon carbide powder is 5~
1 of the total amount of boron carbide powder and silicon carbide powder in the basic component consisting of 50% by volume and the balance consisting of raw coke powder
An oxidation-resistant, high-strength carbon material consisting of a sintered body of a powder mixture in which ~20% by weight is substituted with boride ceramics.