The friction behaviour of steel coating deposited on aluminium using a plasma spray process was investigated in this study. Various parameters and spraying atmospheres were varied for forming different coating microstructures, phases and density values. Addition of oxide phase is known to enhance the friction behaviour and wear resistance. In order to see the friction behaviour of steel coating without oxide, deposition was performed with a shroud that maintained inert gas condition around the plasma. Deposition was also performed under oxygen in order to maximize the oxidation. It is found that coatings contain steel and oxides (FeO, Fe 3 O 4 ). Tribological tests were performed using a ball on disc configuration with a steel ball and WC/Co ball. The coating friction behaviours are completely different for different balls. The worn surface and the ball were characterized with optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The present study focuses on the relationship between the iron oxide formed or not during spaying, the injection parameters into the plasma jet and the microstructural characteristics and the tribological behaviour of the resulting coatings.

Plasma sprayed composite coatings were prepared with a mixed powder of AlCuFeB + aluminium. One focus of this study has been the effect of air plasma spraying processing parameters on the characteristics of quasicrystalline composite coating. In this study, Taguchi L9 design of experiments was employed to study the investigated process parameters. Significant effects on the microstructure were observed. For the composite coating (quasicrystal + aluminium) parameters were optimized, considering phase retention and porosity level. Tribological tests were performed with a ball on disk device at room temperature for this composite coating. Results show that quasicrystal phase can be kept in the coating after spraying.