Over the past years, great achievements have been made in the domain of existing many surface
coating technologies for surface improvement of aluminum alloys. Despite these achievements,
the domination in the market is strongly affected by ability of surface coating technology, by
means of technical and economic considerations, to meet the increased demands for heavy
tribological applications of aluminum alloys. The MPO technology has recently been studied as a
novel and effective means to provide improved properties such as thick and hard ceramic coating
with excellent load-bearing and wear resistance properties on aluminum alloys. The aim of the
present research is to study the properties of MPO coatings deposited on aluminum alloys under
modified conditions so as to improve the hardness of MPO coatings by reducing the porosity
which is the most complex phenomenon can affect the distribution and measurements of hardness,
and wear rates of the coatings. The results proved that the coatings produced by the modified
conditions show significant improvement in porosity and hardness properties for thicker coatings.
Key words: Micro plasma oxidation MPO; aluminum alloys; hardness; porosity.