Silicon Carbide – SiC-3

Silicon Carbide – SiC-3

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Recrystallized Silicon Carbide (RSiC) Unlike the types of SiC mentioned before, the aim here is not to achieve a high final density. The porosity of sintered RSiC is usually about 10 to 20%. For manufacture, a compact green having a bimodal grain size distribution is used in which SiC particles of about 100µm size with fine particles having a diameter of some micrometers are present in a homogeneous mixture. During sintering at a temperature of between 2200°C (3992°F) and 2500°C (4532°F), coarse grains grow at the expense of fine particles, resulting in material densification. Sintering contraction will not occur in this process so that big and complex geometries can be produced from RSiC. Strengths, however, are considerably lower than those of dense variants. However, its extraordinary thermal spalling resistance forms an advantage.

Liquid-Phase Sintered Silicon Carbide (LPSiC) LPSiC is made from a mixture of SiC and one or more oxidic powders. In pressure sintering, a liquid mixed phase is formed which wets particles and ensures densification. LPSiC is generally non-porous and shows considerable fracture toughness besides high strength. However, its production is costly due to the manufacturing process required.

Besides that, there are further variants where bonding in ceramics will not occur through SiC either, but through an additional phase, such as SiC bonded to nitride or silicate.

Typical applications of SiC ceramics comprise especially components subjected to tribological heavy loads, such as friction bearings, pumps, collars or gears, and components under high thermal loads, such as kiln furniture and burner components and those used in semiconductor technology, just to mention some of the most important fields of application.

Date: 2023-04-10     hits: 548    Return