Oxidation and burner rig corrosion of liquid phase sintered SiC

Liquid phase sintering permits lower temperatures to be used to produce SiC with a consequent saving in terms of cost, while maintaining mechanical properties. For application at elevated temperatures, corrosion resistance must also bemaintained.Oxidation in air at 1000 and 1300C of a SiCsinteredwith additions of Al2O3+Y2O3 resulted in protective oxidation kinetics with rates approximately an order of magnitude greater than generally available low-additive SiC. The contaminants present in combustion atmospheres, particularly S and Na, have a marked influence on the rate of material degradation depending on the partial pressure of SO3 and thus the sulphur content of the fuel.Burner rig tests at 1000C resulted in high rates of attack due to the formation of a lowviscosity Na-silicate surface layer in a lowsulphur fuel combustion gas (Jet A1 kerosene).With a low-sulphur fuel (1%Smarine diesel) the high SO3 partial pressure resulted in a low Na2O activity and limited acid (SiO2) base (Na2O) reaction. At 1300C, similar rates of material degradation were observed. Details of the oxidation kinetics and oxidation product morphologies are given.