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Applications of Normal-Pressure Sintered Silicon Carbide Ceramics
Release time:
2021-12-31
Atmospheric-pressure sintered silicon carbide It is one of the widely used materials in structural ceramics. Thanks to its relatively low thermal expansion, high specific strength, high thermal conductivity, hardness, wear resistance, and corrosion resistance—and importantly, its ability to maintain excellent performance even at high temperatures up to 1650°C—silicon carbide ceramics have found extensive applications across various fields.
The commonly used sintering methods for silicon carbide ceramics include: Atmospheric-pressure sintered silicon carbide There are three main types of sintering processes: reaction sintering, liquid-phase sintering, and solid-phase sintering. In reaction-sintered silicon carbide, α-SiC powder is prepared in advance, additives are pressed into the green body, and the green body is brought into contact with liquid silicon at 1500℃. The carbon in the green body reacts with the infiltrating silicon to form β-SiC, which bonds with the α-SiC. Free silicon then fills the pores, resulting in a high-density ceramic material. This material maintains structural stability within a temperature range of 1370℃ to 1410℃. Moreover, the green bodies can be manufactured using conventional ceramic processing techniques. On the other hand, since this process occurs at a relatively low temperature of 1500℃ and does not impose stringent requirements on powder particle size or purity, it enables the production of high-quality products at reasonable prices.
The thermal conductivity and thermal diffusivity of pressure-sintered silicon carbide are significantly higher than those of other structural ceramics. However, due to its high elastic modulus and large coefficient of thermal expansion, pressure-sintered silicon carbide ceramics exhibit poor resistance to thermal shock; their thermal-shock resistance is notably lower than that of silicon nitride (but slightly higher than that of zirconia ceramics). The thermal-shock performance of a material depends on its specific application. For instance, in applications involving rapid temperature changes, silicon nitride outperforms silicon carbide. On the other hand, silicon carbide’s high thermal conductivity can deliver superior performance when temperature changes are relatively small.
The fracture toughness of pressure-sintered silicon carbide ceramics is often lower than that of other structural ceramics, which has raised concerns about the application of silicon carbide ceramics in certain internal combustion engines. For example, turbine rotors could potentially fracture under external forces. Pressure-sintered silicon carbide is an excellent abrasive material. Wear tests have shown that silicon carbide exhibits good resistance to abrasion when exposed to particles or mixtures. Compared with single-phase sintered materials, reaction-sintered silicon carbide also demonstrates relatively poorer resistance to acids, bases, and high-temperature combustion products.
1. Atmospheric-pressure sintered silicon carbide Granulation powder
Features: Primarily used for the production of pressureless (atmospheric-pressure) silicon carbide ceramic products. Sintered pressureless silicon carbide ceramics exhibit excellent wear resistance, high-temperature resistance, resistance to strong acid and alkali corrosion, high strength, high hardness, and a low coefficient of friction.
Applications: Widely used in industries such as petroleum, chemical engineering, metallurgy, mining, aerospace, and military industry.
Technical specifications: The morphology of the granulated particles—thanks to centrifugal spray granulation—the granulated powder exhibits a perfectly spherical shape, with a narrow and uniform particle size distribution, thereby improving flowability.
2. Atmospheric-pressure sintered silicon carbide ceramic products
Features: This material is produced by vacuum sintering at 2150℃ using pressureless sintering of sub-micron silicon carbide powder. It boasts high strength, high hardness, excellent wear resistance, high thermal conductivity, a low coefficient of friction, high temperature resistance, and resistance to acids and alkalis.
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