Interaction of some pollutant oxides on durability of silicon carbide as a material for diesel vehicle filters

The short-term interaction of SiC and some single pollutant oxides (Na2O, PbO and V2O5) was investigated as a function of temperature by X-ray diffraction (XRD) and Fourier transform infrared (F. T-i.r.) analysis. Sodium oxide dissolves the protective silica layer forming glassy sodium silicates at a temperature of 550 degrees C. V2O5 accelerates SiC oxidation, leading to the formation of large amounts of silica at temperatures above 750 degrees C. PbO begins to react with silica film at 600 degrees C forming Pb2SiO4. Degradation becomes highly destructive at higher temperatures. Given the presence of Na2O, PbO and V2O5 in diesel particulates and the temperatures that filters must tolerate, SiC appears to have insufficient thermal and chemical resistance for this application.