Characterization of thermally protective Al2O3-TiO2 coating fabricated by atmospheric plasma spraying

In this study, Al₂O₃-based coatings with varying TiO₂ contents (0, 3, 13, and 40%) were fabricated using atmospheric plasma spraying technique. To compare the superiority of the samples, their mechanical (Vickers hardness and adhesion strength) and thermal properties (thermal conductivity and thermal shock resistance) were characterized. As observed, Al₂O₃-40%TiO₂ (A-40T) coating exhibited relatively inferior mechanical properties but superior thermal insulation and thermal shock resistance at 600°C. According to the microstructure and phase analysis, this finding can be attributed to the special phase, Al₂TiO₅, and the pre-existing microcracks inside the coating. Thus, A-40T manifested excellent characteristics for thermal insulation application compared with pure Al₂O₃ and low-TiO₂ content coatings.

Keywords: Atmospheric plasma spray (APS); Al₂O₃-TiO₂ coating; Mechanical property; Thermal property; Microstructure