Characterization and wear behaviour of PEO coatings on 6082-T6 aluminium alloy with incorporated α-Al2O3 particles

Plasma electrolytic oxidation (PEO) coatings with incorporated α-Al2O3 particles were formed on 6082-T6 alloy. Effects of particle concentration on phase composition and wear behaviour were investigated. Tribological performance was compared with that of electrolytic hard chrome. Results suggested that α-Al2O3 particles are incorporated into the outer layer of the coatings either by deposition, electrophoresis or mechanical entrapment by the material ejected from the discharge channels. As a result, the outer layer shows lower porosity and increased hardness. Friction coefficients of untreated 6082-T6 alloy and hard chrome coating remained relatively unaffected as the normal load increased from 2 to 10 N. Friction coefficients of PEO coatings slightly increased with the applied load and were similar or slightly higher than those of hard chrome. PEO coatings with incorporated α-Al2O3 particles showed the lowest wear volumes among all tested materials, suggesting that they could be a promising alternative to hard chrome coatings.