Tialite formation from its quasi-amorphous stoichiometric co-precipitated powder by thermal spray process

In this work, the formation of tialite from powders obtained by the co-precipitation method with inorganic salts was investigated. For the co-precipitation process, a solution of aluminum nitrate (Al(NO3)3   9H2O) and titanium tetrachloride (TiCl4) in ethyl alcohol was co-precipitated with an increase in ammonium hydroxide base. Phase transformations of the quasi-amorphous dried gel with stoichiometric composition of tialite treated in a muffle furnace and in an atmospheric plasma thermal spray deposition were explored. The effect of calcination thermal treating on the tialite formation was evaluated for different temperatures (400, 600, 800, 900, 1000, 1200, 1300, and 1400 °C). The powder was thermally treated by calcination at 600 °C for 6 h prior to the thermal spray process. Dried gel pieces were also calcined at 600 °C for 6 h and ground, the produced powders were thermally sprayed onto a stainless steel substrate and the formed coating was mechanically detached from the substrate and then characterized. It was confirmed that the thermal spray process transformed the quasi-amorphous powders to single tialite phase. The absence of the corundum and rutile phases was attributed to the high heating and cooling rates (~ 106 K/s) supplied by thermal spray processing.