To manufacture Reaction Bonded Silicon Carbide (RBSC), Silicon is infiltrated into a pre-formed silicon carbide/carbon powder green body which is then fired. This gives rise to around 10% free silicon, which fills the pores. The resulting microstructure has low porosity and a very fine grain. Shaping is normally carried out before firing, but the fired compact can be diamond ground to around 0.01mm tolerance. However, it is difficult to machine after firing. The material has high strength up to 1350C which results in its use as high temperature gas turbine components. The high hardness (harder than tungsten carbide) means that it is used extensively for bearings and seals. The high thermal conductivity combined with low thermal expansion leads to good thermal shock resistance. RBSC can tolerate a wider range of acids and alkalis than either tungsten carbide or alumina. Its oxidation resistance helps to give long service life in furnace applications.