Production of TiAl2O3 composite ultrafine particles by radio-frequency plasma and their characterization

TiAl2O3 composite ultrafine particles (UFPs) are successfully produced by putting a mixture of two kinds of raw powders into radio-frequency plasma. The deviation in the composition of the UFPs from that of the raw-powder mixture is about 1% on the average and no contamination occurs during the plasma processing. The UFPs consist mostly of α-phase Ti and α-, γ-, δ- and θ-phase Al2O3 with the probability of forming other phases such as TiAl intermetallic compounds and TiAlO complex oxides being very low. The results of static and dynamical calculations indicate that this is because the probability of contact between the evaporated Ti atoms and the Al2O3 molecules in the plasma flame is low. All the UFPs exhibit similar bimodal size distribution curves, where the peaks are located at about 70 and 700 nm independent of the composition.