Effect of surface nanostructuring of aluminum alloy on post plasma electrolytic oxidation

AAl230 aluminum alloy samples were coated by plasma electrolytic oxidation (PEO). The samples with and without surface mechanical attrition treatment (SMAT) were coated in phosphate- and silicate-based electrolytes and in the presence of Si3N4 nanoparticles. Besides, morphology and properties of the produced coatings were examined. To determine the corrosion resistance of the coatings, potentiodynamic polarization technique was used. All coated samples were subjected to wear test in order to compare coating wear properties of the SMATed and unSMATed samples. Then the effects of SMAT preprocessing and its duration on the properties of the coatings prepared by PEO were investigated. The results indicated that the mean coefficient of friction of the coated samples decreased by near 83% with respect to the uncoated (raw) samples. Furthermore, the SMATed samples showed thicker coatings as compared to unSMATed samples due to an increase in their matrix reactivity. (C) 2014 Elsevier B.V. All rights reserved.