A study on wear and corrosion behaviour of-thermally sprayed alumina-titania composite coatings on aluminium alloys

摘要

In this study, Al_2O_3-13TiO_2 + 10 % polytetrafluoroethylene (PTFE) powders were sprayed using both flame and plasma spray processes after a NiAl bond layer was deposited on 2024-T6 aluminium alloy substrate. The characterization of the coatings was made by microscopic examinations, thickness, surface roughness, porosity and hardness measurements and X-ray diffraction (XRD) analysis. Corrosion and wear performances of the samples were analysed by using a potentiodynamic polarization scanning (PDS) technique and a reciprocating wear tester, respectively. It was found that the flame and plasma sprayed Al_2O_3-13TiO_2 + 10 % PTFE coatings possessed about two and four times higher wear resistance than AA2024-T6 substrate, respectively. When compared to the flame sprayed Al_2O_3-13TiO_2 + 10 % PTFE coating, the plasma sprayed Al_2O_3-13TiO_2 + 10 % PTFE coating with a lower porosity showed higher hardness and better wear and corrosion resistance.