Aluminium nitride by plasma spraying of an Al2O3–C–Sm2O3 system

Increasing demand for high performance ceramic dielectric substrate materials has led to the use of AlN due to its high thermal conductivity, low dielectric constant and co-efficient of thermal expansion (CTE) compatibility with that of silicon. This paper reports on a thermal plasma spraying process which enhanced the reactivity of an Al2O3–C–Sm2O3 system so that subsequent heating at 1400°C was sufficient to fully convert it to hexagonal AlN spherical particles with a particle size of about 2.45 μm. It was thought that the increase in reactivity was due both to the formation of the integrated composite powder by plasma spraying, which reduced the overall endothermic heat required for the nitridation reaction, and the liquid phase sintering effect of SmAlO3 during the process.