JPS609980B2 - Manufacturing method for carbon, silicon, and boron-based shaped sintered bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a high-density and high-strength shaped sintered body of the three elements carbon, silicon, and shelf elements.

Materials that can withstand extremely high temperatures are required to have properties such as not softening in that high temperature range, having line deformation that is similar to that of water, and being resistant to thermal shock. Graphite/carbonaceous materials, silicon carbide materials, carbide-based materials, silicon nitride materials, and the like are known as materials that can meet these requirements. However, in the case of high-temperature steels of 150,000 or higher, all of the other materials except graphite and carbonaceous materials have the disadvantage that they cannot maintain sufficient durability due to significant deterioration in mechanical strength. On the other hand, graphite/carbonaceous materials have the characteristic that their mechanical strength increases even at temperatures exceeding 200,000°C, but the absolute value of this strength is small, and due to their dexterity, detailed machining cannot be performed. The drawback was that it could not be used as a structural material under high temperatures. The inventors discovered that the carbon material has the highest melting point in a non-oxidizing atmosphere and has chemical resistance, and as mentioned above, the carbon material has the highest melting point and chemical resistance.
Focusing on the fact that carbon-based materials have the advantageous property of gradually increasing mechanical strength at high temperatures, we have improved the inherent shortcomings of graphite and carbon-based materials, such as lack of absolute mechanical strength and brittleness in high-temperature ranges. As a result of extensive research, we have found that finely ground carbon powder is mixed with metallic silicon powder, silicon carbide powder, or a mixture of both powders, and shelving chemicals such as &03, 3803, etc., and the mixture is heated under specific conditions. It has been found that a molded cord body that satisfies the above-mentioned objectives can be obtained by firing the molded cord body.

The present invention has been completed based on the above findings, and the gist thereof is to add 50 to 9 weight percent of carbon powder and 2% of silicon metal powder and/or silicon carbide powder in terms of silicon.
~ 4% by weight and a shelving compound as a sintering aid, 5 to 3% by weight converted to shelatomic oxides are added and mixed, and this mixed powder is heated at a temperature of 1600 qo or more under a pressure of 100 kg' or more. The present invention relates to a method for producing a shaped sintered body based on carbon, silicon, and shelving elements, which is characterized by heating to .

The conditions and blending ratio of the raw materials used in the present invention will be explained below. As the carbon powder, amorphous carbon such as coke or carbon black having a carbon content of 97% or more is preferably pulverized to an average grain size of 5 mm or less. This is because if the carbon powder is less than 5% by weight, it will not be possible to maintain the gradual increase in mechanical strength at high temperatures of graphite/carbon-based materials, and if it exceeds 9% by weight, high strength will not be exhibited.
Metallic silicon should have a purity of 95% or higher, and silicon carbide should have a purity of 9.
Use 2% or more.

Metallic silicon melts or vaporizes during heating, so it can be used if it is crushed to 74 grains or less, but silicon carbide can be used if it is crushed so that the average particle size is 5 grains or less, although this is not a limitation. Preferably, powder is used. It appears that most of metallic silicon reacts with carbon during heating to produce silicon carbide. The amount of silicon metal or silicon carbide, or a mixture thereof, should be in the range of 2 to 4% by weight, calculated as silicon. In other words, the converted amount of added silicon is 2
This is because if it is less than 40% by weight, no clear effect on improving mechanical strength is observed, and if it exceeds 40% by weight, the properties of graphite are reduced and workability is also reduced, which is not preferable. The purity of the raw materials used, carbon powder, metallic silicon, and silicon carbide, was determined individually because if the impurities contained in the raw materials used are carbon or silicon, it is possible to calculate and correct the amount of raw materials used. If silicon is contained, the oxygen element reacts with carbon and becomes gasified*, causing a reduction in product density.Also, if metal elements other than silicon are present, they may form carbides or melt and aggregate. This is because the material becomes hard and forms so-called hard spots, which impairs machinability.

Examples of shelving compounds that can be used include B203 and Hi-3803.

If the amount added is less than 5% by weight calculated as &03, the silicon carbide produced by the reaction between carbon and the blended silicon carbide or metal silicon and carbon will not easily sinter, and &03
If the amount exceeds 3% by weight, the amount of carbonized carbonized carbonized chloride produced by the reaction increases and the characteristics of graphite are lost. should be within the range of The blending conditions for the raw material powder of the present invention are as described above, and a particularly preferred blending range for a three-component system of carbon, silicon, and rigid oxide is the shaded range in the attached diagram. .

In the figure, point A is (C; 55%, Sj: 40% "B0
3:5%), point B is (C: 50%, Si: 40%, B2
03:10%), point C is (C:50%, S word 20%,
B203: 30%), point D is (C: 68%, Si; 2%
, B203: 30%), point E is (C; 93%, Si; 2
%, &03:5%). Examples of formulations are shown below.

Table 1 Mixture Name of raw materials for the invention product 1 2 3 4 5 6 7 8% by weight) Coal pitch coke 84.5 81 67
62.5 56 61.6 64
．． 3 carbon black
81 Metal Silicon 66 6
26 24.5 - 6 13
19.6 Silicon carbide
37.3 18.
6 94 Anhydrous Shelf Element 90 13
70 13.0 6.7 13 6
7 67 The purity and particle size of the raw materials used are shown in the table below.

Purity Particle size Coal pitch coke 99.6% Average particle size 5 m or less Carbon black 99.8 Metallic silicon 96
Poly 74〃m or less Silicon carbide 96.5%
Average particle size: 5〃m or less Anhydrous element 96.6% After thoroughly mixing the raw material powders blended according to the above recipe, it was filled into an artificial graphite mold with an inner diameter of 25 ribs, and the mixture was heated to 2200 mm under pressure using a 200K9'C tiger. The temperature was raised to ~225,000 in 40 minutes, and the temperature was maintained for 30 minutes for shaping and sintering.

A high frequency induction heating method was used for heating. After cooling, the diameter is about 2
5 willows The physical properties etc. of the shaped burning bodies of approximately 25 willows in height were measured. The results are shown in Table 3. For comparison, conventional graphite
Measured values for carbonaceous materials and silicon carbide materials are also listed. Table 3 (Sho 1, 2) Electrical resistance and compressive strength were measured in the pressing direction during molding.

(Part 3) The graphite/carbonaceous material is made by adding lupitch as a binder to high-grade natural graphite and high-grade petroleum coke. Knead under heat. Molded and baked at 1300℃ with no air allowed, chemical composition: ○: 97%, Si02:
i-kyo. A-20s: 0.2 shot (Rin 4) Silicon carbide material is made by adding a small amount of clay as a binder to 72 silicon carbide to adjust the particle size. Molded and fired, chemical composition is Si
o: 90%. Si02: 6.6%. Aso202:1.3
% The molded body of the invention product 3 was processed to have a diameter of 15 willow and height of 2. It was placed in a graphite mold with an inner diameter of 25 willow and heated to 1000 k.
As a result of high-frequency induction heating under pressure of g' ground, 160
At 0oo there was no change at all, at 1800oo there was a 1% shrinkage, and at 1900qo there was only a 3% shrinkage in the height direction and a 1.5% bulge in the radial direction. As described above, the shaped burnt striped body according to the present invention contains shelf elements partially forming a solid solution with carbonized shelf elements and partially with graphite,
Most of the shelf elements are contained in the form of silicon carbide, so conventional graphite/carbonaceous materials whose main component is graphite have a compressive strength of 54.
0kg/c heat resistance, all the products of this invention are 1000k9
It can be said that it is a graphite/carbon-based molded product that is larger than a 'c tiger and has excellent mechanical strength.

Furthermore, since it can be machined using a lathe, etc., it can be used in applications such as sealing materials and bearings for high-speed rotating equipment, which require wear resistance, and oxidation resistance due to the fact that they contain shelf elements and silicon. It can be used for heat exchange parts that are exposed to relatively high temperatures in an oxidizing atmosphere, and high strength mechanical parts that are exposed to extremely high temperatures in a non-oxidizing atmosphere, and high strength for thermal or electrical conduction. The shaped sintered body according to the present invention can be used for members and the like.

[Brief explanation of the drawing]

The attached figure shows the preferred blending range of the compounding materials used in the method of the present invention in terms of a three-component system of carbon, silicon, and shelium oxide.

Claims (1)

[Claims] 1 50 to 93% by weight of carbon powder, 2 to 40% by weight of metallic silicon powder and/or silicon carbide powder in terms of silicon, and 5 to 30% of boron compound in terms of boron oxide as a sintering aid. % by weight and mix this mixed powder to 100k
A method for producing a carbon-, silicon-, or boron-based shaped sintered body, which comprises heating to a temperature of 1600° C. or higher under a pressure of g/cm^2 or higher.