The effects of graphite additive on the surface propertiesand investigation of the wear behavior of AA-2024 aluminum alloy in micro arc oxidation process

In this study, coating process was carried out on the surface of AA-2024 aluminum alloy by micro arc oxidation method. Two different electrolytes were prepared basic alkaline electrolyte and by adding graphite particles into this electrolyte. The effect of graphite on the surface properties and tribological behavior of the oxide layer formed on the sample surface was investigated. The surface roughness, coating thickness, phase composition and wear behavior of the coated samples were examined. The results show that the breakdown voltage was decreased with the addition of graphite particles. It has been observed that surface roughness increases significantly after coating with micro arc oxidation method. However, The surface roughness improves with the addition of graphite particles. It was observed that there was not much change in the coating thickness values of the coated samples with graphite additive and non-graphite additive. The results show that the dominant phases were α-Al2O3 and γ-Al2O3 phase in both coated samples with graphite additive and non-graphite additive. In addition to this, the number of pores formed on the coating surface were decreased with the addition of graphite particles. Besides, the hardness of the sample from the substrat material to the dense intermediate layer increased and from dense intermediate layer to the outer layer decreased. As a result of the investigation, the wear resistance of AA-2024 alloy were increased significantly after coating. Key Words: Micro arc oxidation, Graphite, AA-2024, Wear resistance