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

Abstract

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(NO 3 ) 3 9H 2 O) and titanium tetrachloride (TiCl 4 ) 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 (~10 6 K/s) supplied by thermal spray processing.

Experimental and Theoretical Studies of the Thermal Behavior of Titanium Dioxide−SnO2 Based Composites

“…This reaction is followed by TG. As observed (Figure ), the data represented by TS0 show mass loss without the observation of any plateau and similar behavior has been also observed elsewhere − for the same compound. The calculated kinetic order for this particular system (TS0) is 1 (Figure a), while its activation energy changes from 80 kJ at 250 °C to 130 kJ at 500 °C (Figure c).…”

“…The samples TS15 and TS30 have TiO 2 and butyl radicals in their compositions. The analyses of TG curves (Figure ) are done considering different temperature ranges: below 350 °C (first step) and between this temperature and 500 °C (second step) when the degradation reaction is over. − Both systems lose H 2 O which is possibly trapped in the crystal as moisture. The next event starts beyond 350 °C consisting in the degradation of the butyl group.…”