Finely-structured titania (TiO2) coatings by solution precursor plasma spraying from various TiO2 liquid feedstocks

The coatings developed via solution precursor plasma spraying (SPPS) are dependent on the properties of the plasma jet and spray parameters. The thermal transport properties such as dynamic viscosity and thermal conductivity of Ar+H2 plasma working gases was numerically investigated in the presence of various titania (TiO2) precursor solutions. Alcoholic solutions of titanium isopropoxide (TIP) and titanium butoxide (TB) were used. The transport properties were greatly influenced by these solutions expecting a high ability of heating factor of the plasma jet, enough to obtain fine-structured TiO2 coatings. Experimentally, TiO2 coatings were developed via SPPS using these solutions and their microstructural characteristics were studied. The thermal behaviour was studied via simultaneous thermal analysis using DTA-TG equipment. The phase composition, functional groups and optical absorption characteristics of the coatings were determined using XRD, FTIR and UV-Vis spectroscopic techniques, respectively. The formation of polycrystalline TiO2 coatings was confirmed by phase analysis for both precursors. Porous coatings were obtained when using short spray distances while dense coatings were obtained using higher spray distance owing to the longer residence time of particles inside the plasma jet. Results suggest that the micro-structural features of TiO2 coatings can be tailored by varying the operational plasma spray parameters.