Plasma sprayed oxides are an effective solution when wear and corrosion resistance are demanded. However,  low particle velocity in the plasma jet causes limited interlamellar cohesion. HVOF-sprayed ceramic coatings emerged as an improved alternative. The increased particle velocity results in denser coatings with good interlamellar adhesion.
In this paper, tribological performances of plasma and HVOF sprayed alumina and chromia coatings are compared. Both normal fraction and nanofraction HVOF coatings are studied.
The microstructure has been analysed by SEM, EDS and residual stresses measured by XRD. Mechanical properties (hardness, elastic modulus) have been investigated by instrumented indentation. Steel wheel and rubber wheel tests have been used to asses dry particle abrasion resistance. Pin-on-disk tests at different temperatures (up to 800°C), loads and sliding speed have been performed. Wear tracks have been observed by SEM. The time evolution of the corrosion mechanism in aqueous solutions has been investigated by electrochemical impedance spectroscopy.