Influences of Current Density on Tribological Characteristics of Ceramic Coatings on 6061 Al Alloy by Plasma Electrolytic Oxidation

Plasma electrolytic oxidation (PEO) of an 6061 Al alloy was accomplished in an electrolyte with sodium hexametaphosphate (10 g/L) and sodium silicate (10 g/L) Coatings were produced at four different current densities (4, 6, 8 and 10 A/dm(2)). Phase composition, morphology and tribological characteristics of the coatings were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and ball-on-disk friction testing. The results show that among the four ceramic coatings which were produced under four current densities, the coating produced under the current density of 8 A/dm(2) got the lowest wear rate with the value of 4.5 x 10(-5) g/m.