Particles deposited with a thermal spray process have a large cooling rate during coating formation. In this study, the effect of different cooling rates on plasma sprayed alumina was investigated. The cooling rate of particles has an important effect on alumina phase formation and crystallite size. Basically the corundum phase was observed when cooling rate is low, but with an increase in the cooling rate, nanocystallites of gamma alumina and amorphous alumina are formed.

Keywords: corundum; gamma alumina; amorphous alumina; thermal spray; cooling rate