Fine Ceramic Silicon Carbide Products

Only highly dense ceramics with high thermal shock resistance can be utilized for such strongly mechanically and thermally stressed components. These demands are met by hot-pressed silicon carbide produced at pressures of 350 bar and sintering temperatures of 1900 to 2000°C. The necessary, but very expensive, mechanical finishing is disadvantageous for industrial manufacture of hot-pressed silicon carbide. 

Development of fine ceramic SiC-products open up new application possibilities  

Pressureless sintering of SiC is only possible with extremely fine powders 

Reaction sintering by reacting liquid silicon sucked into pores with graphite 

It is technically easier to manufacture a molded component from SiC-powder by slip casting or dry pressing, working it mechanically and then sintering pressureless at 1950 to 2000°C. Due to the low sintering activity of silicon carbides, such processes have only been recently successfully carried out with the advent of fine particulate SiC-powders (specific surface area 5 m /g) with low oxygen-contents ( 0.2%). Boron or aluminum and free carbon or boron carbide are added as sintering aids. 

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Krstic, V., Production of Fine High-Purity Beta Silicon Carbide Powder, J. Am. Ceram. Soc., 75(1) 170-174 (1992)... 

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