Dense SiC Shapes

This product group is based on oxide- or nitride-bonded SiC grains and exhibits an apparent porosity of up to 20% by volume. A fracture surface of a silicon nitride bonded SiC is shown in Fig. 12a. 

The amount of free silicon in infiltrated silicon carbide is usually between 10% and 15%. It is difficult to bring this below 5%. Infiltration is relatively easy, because of the good wettability of the material, although there are problems if the bodies are large or thick, because of the exothermic reaction and the expansion of silicon on freezing, which make perfect impregnation difficult. 

Reaction sintering can, however, usually be controlled so that the change in volume is negligible, resulting in dimensionally accurate components. This is 

Pellet-like parts in pressing directions not higher than three times the diameter hole distances not less than 0.2 diameter hole diameter 0.1 height of part 

Extrusions which can be cut to size, diameters 1.5-40 mm wall thickness 1 mm, lengths up to 1000 mm 

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