In the present study, the abrasive wear characteristics of the plasma electrolytic oxide (PEO) and the plasma electrolytic carburized (PEC) coatings on a 6xxx series aluminium alloy were compared. The PEO process involves oxidation of the metal surface by plasma and electrochemical reactions to form a hard ceramic oxide layer in an ambient and low concentration alkaline solution, in contrary, the PEC process involves diffusion of carbon onto the surface of a quenched metal piece in an organic-based electrolyte and hence hardening of substrates at much higher temperatures. The microstructural characteristics of the coatings were characterized by scanning electron microscopy, X-Ray diffraction and image analysis. Abrasion tests were conducted following the guidelines of ASTM G105, using abrasive slurry. The effects of rotating wheel velocity and coating properties (microstructure for PEO and nanostructure for PEC) on the abrasive wear mechanism and mass loss have been investigated. The PEO-treated aluminium alloy was found to have better abrasive wear resistance than the PEC-treated alloy and the uncoated materials.
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