Physico-chemical characterisation and tribological behaviour of ground micro-arc oxidation coating on aluminium alloy – Comparison with hard anodised oxidation

This study aims to compare the tribological properties of classical hard anodisation (HA) and a ground micro-arc oxidation (MAO) coating. Analysis on MAO showed that its hardness and elastic modulus are around three times greater than HA. Wear tests were evaluated using a linearly reciprocating ball-on-flat using alumina balls. The HA coating did not withstand the test. The substrate was severely degraded. MAO coating wear rate is 3.1 × 10−5 mm3 N−1 m−1. It is 22 times lower than that on HA coating. Energy dissipated calculation showed that 26 kJ is needed to remove 1 mm3 of materials from MAO tribocouple. Conversely, only 0.7 kJ is needed to remove 1 mm3 from HA tribocouple.