The effect of trace amounts of copper on the microstructure, stability and oxidation of macroporous silicon carbide

Trace amounts of copper have advantageous effects when creating macroporous silicon carbide monoliths to be used for combined diesel particle filter and catalyst support systems. These structures were produced from a slurry of silicon, graphite, aluminium and copper. Mixed with water, extruded and dried, the resulting bodies were pyrolyzed, sintered, and then partially oxidized, to yield a mechanically stable porous 4H-SiC microstructure with an average pore diameter of 20 μm and average accessible porosity of 57%. The Cu alloys with the Si and Al to create the sintered body via a liquid phase, and prevents the build-up of undesirable Al-containing ternary carbide crystals in the microstructure. The Cu promotes oxidation of SiC to form a 80 nm SiO2 layer that serves as a good catalyst support. The accelerated oxidation can be intercepted by dissolving the Cu component from the monoliths with an acid solution.