Corrosion behaviour of infiltrated reaction sintered silicon carbide

Silicate carbide (70 wt%), graphite (30 wt%) and infiltrant (5 wt%) were used to prepare green bodies which were fired in silicon atmosphere at 1700 C to produce samples for corrosion studies. Reaction sintered silicon carbide infiltrated with B4C, VC or MoSi2 is resistant to molten lead and zinc and attack by molten aluminium is almost negligible. It is also resistant to molten sodium chloride but is attacked by molten sodium carbonate and molten sodium sulphate due to the formation of sodium silicate. Enhanced attack results from a higher content of free silicon in the sample which leads to more silica formation on the surface due to oxidation. Samples are severely attacked by molten cast iron but to a lesser extent than reaction sintered silicon carbide without infiltration. 7 refs.