The SiCAlN system: Influence of elaboration routes on the solid solution formation and its mechanical properties

Abstract

Highly densified SiCAlN samples were prepared from commercial powder mixtures by hot-pressing in the range 2050–2150°C. Due to the respective high values of thermal conductivity of both SiC and AlN and the electrical resistivity of AlN, it should be interesting to study the mixture, or the solid solution, for potential substrate applications. Using XRD analysis and calculation of lattice parameters, the solid solution under the 2H structure was pointed out. However, high temperature polytypes were also determined in samples with high SiC contents even at a sintering temperature of 2150°C. In order to improve the mechanical properties, slurry elaboration routes and sintering cycles adapted to SiC contents were investigated—microhardness, fracture toughness and flexural strength were measured. According to the chosen sintering cycle, flexural strength values were different; and values in the range of 1000 MPa were obtained for high SiC contents. Thermal conductivity was measured, but the solid solution formation induced a decrease of it.