Boron carbide base composite ceramic and preparation method thereof

Abstract

The invention discloses a boron carbide based composite ceramic and a preparation method thereof. The boron carbide based composite ceramic comprises the following compositions by weight percentage: 45 to 50 percent of boron carbide powder, 5 to 8 percent of phenolic resin, and 42 to 50 percent of metallic silicon. After the compositions are weighed, the phenolic resin is dissolved by alcohol first, and the boron carbide powder is added for mechanical ball milling to be mixed evenly; a granulator is used for granulation, and a green body with a shape of the needed product is obtained through compression molding; the compressed green body is placed into a baking oven for drying solidification; the weighed metallic silicon is added into a graphite crucible, the solidified green body is placed on the metallic silicon and is placed into a high-temperature vacuum sintering furnace for sintering along with the crucible, the sintering temperature is between 1,550 and 1,700 DEG C, and the green body is cooled with the furnace after the thermal insulation for 1 to 3 hours to obtain the boron carbide based composite ceramic. The phenolic resin plays a role in an adhesive and a carbon sourceduring the preparation of the composite ceramic, and can also play a role in providing the green body with excessive air holes during the sintering, so that the infiltrability of silicon is improved.

Description

technical field [0001] The invention relates to a composite ceramic and a preparation method thereof, in particular to a boron carbide-based composite ceramic and a preparation method thereof. Background technique [0002] Boron carbide has a high covalent bond content and a small specific surface area. Its room temperature hardness is only lower than that of diamond and cubic boron nitride, and its near-stable high-temperature hardness is unmatched by other materials. Since boron carbide itself diffuses very slowly at the grain boundary, the temperature of pressureless conventional sintering is very high, and its relative density generally does not exceed 90%. In order to reduce the sintering temperature of boron carbide, researchers have added metal or other ceramics such as aluminum, boron nitride, aluminum oxide, tungsten carbide and titanium carbide to boron carbide materials, and have made some progress, but the sintering temperature is too high issue remains unresolv...

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Problems solved by technology

[0008] The above four preparation methods can obtain boron carbide materials with higher density and better mechanical properties. As the main methods used in the production of boron carbide ceramics at present, hot isostatic pressing and hot pressing sintering methods, the former cannot be obtained due to the high cost of products. Large-scale production, the cost of the hot pressing method is relatively low, but the performance stability of the product is poor, the impurity content is high, and the mechanical performance is unstable, and both methods have the problem of large line shrinkage before and after sintering, which makes it difficult to prepare products with shape changes

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