A new way to in-situ synthesize Rutile TiO2 coating

This study presents the manufacturing of a pure rutile TiO₂ coating by Very Low-Pressure Plasma Spraying (VLPPS) process. VLPPS was used in reactive mode injecting both titanium powder and oxygen gas to elaborate nano-size rutile TiO₂ coating on steel substrates. The optical emission spectroscopy was used to analyze the properties of the plasma jet. Microstructures, phases composition, and properties of such coatings were characterized with respect of the operating parameters. The results show that oxidation reaction of Ti vapor species takes place not only in the plasma jet but also on the substrate. The surface of the coating shows typical cauliflower microstructure as the cross-section of the coating presents a columnar microstructure. The rutile TiO₂ coating with (110) preferred direction was successfully manufactured by the complete vapor condensation during VLPPS process. The rutile TiO₂ coating presents higher microhardness than other titanium oxide coatings.