Sintered Silicon Carbide Properties and Applications

Application of silicon carbide ceramics

Silicon carbide ceramics have been widely used due to their high hardness, high corrosion resistance and high temperature strength. There are mainly the following aspects:
Sealing ring: Silicon carbide ceramics have good chemical corrosion resistance, high strength, high hardness, good wear resistance, low friction coefficient, and high temperature resistance, so it is an ideal material for making sealing rings. When it is combined with graphite materials, its friction coefficient is smaller than that of alumina ceramics and cemented carbide, so it can be used for high PV values, especially in the working conditions of conveying strong acids and strong alkalis.
Grinding medium: Silicon carbide ceramics are widely used in wear-resistant mechanical parts due to their high hardness, especially the grinding medium (grinding medium) in ball mills. The grinding medium used in ball mills has an important influence on grinding efficiency. Its basic requirements are high hardness and good toughness to ensure high grinding efficiency and less doping.
High temperature corrosion-resistant parts: One of the most important characteristics of silicon carbide ceramics is its high temperature strength, that is, the strength is basically not reduced at 1600C, and the oxidation resistance is very good, so it can be used in high temperature structural parts. Such as the top plate and bracket of high-temperature furnaces, and fixtures for high-temperature experiments.
Summary: SiC ceramics have shown excellent performance in many industrial fields, and have attracted widespread attention. SiC ceramics are a large family in the field of inorganic non-metallic materials, and their tentacles extend to almost all industrial fields. However, due to the difficulty of sintering SiC ceramics, its manufacturing process and production are relatively expensive. Reducing the firing temperature of SiC ceramics and finding new and cheap production processes are still the research focus of material workers. SiC ceramics have broad development and application prospects.

Characteristics of sintered silicon carbide

SiC ceramics sintered by pressureless sintering, hot pressing sintering, hot isostatic pressing sintering and reaction sintering have different performance characteristics. In terms of sintering density and flexural strength, hot pressing sintering and hot isostatic pressing sintering SiC ceramics are relatively high, while reaction sintering SiC is relatively low. On the other hand, the mechanical properties of SiC ceramics also vary with the sintering additives. Pressureless sintering, hot pressing sintering and reaction sintering SiC ceramics have good resistance to strong acids and strong alkalis, but reaction sintering SiC ceramics have poor corrosion resistance to super strong acids such as HF. In terms of high temperature resistance, when the temperature is lower than 900℃, the strength of almost all SiC ceramics is improved; when the temperature exceeds 1400℃, the flexural strength of reaction sintered SiC ceramics drops sharply. (This is because the sintered body contains a certain amount of free Si, and the flexural strength drops sharply when the temperature exceeds a certain temperature) For pressureless sintering and hot isostatic pressing sintering SiC ceramics, their high temperature resistance is mainly affected by the type of additives.

Silicon carbide pressureless sintering furnace