The role of Aluminium in the synthesis of Mesoporous 4H Silicon Carbide

Aluminium was found to play a key role in the process of forming a mechanically stable and highly porous, granular structure of 4H silicon carbide. The material was prepared by a high temperature reaction of the elemental constituents. The reactions were carried out under different background atmospheres, including nitrogen. Ternary carbides containing Al, Si and N were formed in the process, and these are believed to be responsible for the final outcome of the process at the highest reaction temperatures, in the form of pure well-connected grains of 4H-SiC, forming a strong and rigid microstructure with high porosity. The Al containing compounds function as structural promoters for the 4H polytype recrystallization. This is expected − and was partly shown − to take place through substitution with 4H-SiC and the evaporation of all other constituents during the high temperature sintering step. When extruded into a honeycomb structure, this sintered pure mesoporous SiC final product turns out to be ideal for a combined diesel particulate filter with support for catalysts in the pores.