Investigation of wear behaviour of aluminum alloy coated with micro arc oxidation method

Micro arc oxidation method is the process of coating with hard, abrasion and corrosion resistant surface by immersing the substrate in an electrolytic liquid by effect of electrochemical reaction through the plazma discharge. In this study, two-step coating is applied on aluminum(Al7075) by micro arc oxidation method. In the first step, the samples are coated aluminum oxide in the solution of potassium hidroxide, sodium aluminate and sodium phosphate. In the second step, coating is performed by adding 0,8 gr/lt Ti particules in the same solution. For both solutions, the frequence, voltage and processing time varied as 100-350 Hz, 450-550V, 10-30 min, respectively. After the coating process, measurements are carried out for analyzing the impact of experimental parameters(voltage,frequence and processing time) and Ti addition. Afterwards wear tests are applied on coated samples on block-on-disc abrassion test unit. As a result of this review, it has been seen that, surface roughness increases with increasing voltage, frequence and processing time and the maximum increasing occures in voltage parameters. Coating thicknesses are affected by the addition of Ti particules. Ti added coatings are thicker and rougher than non additive samples. When considering the effects of coating wear parameters, the amount of wear decreases with the increasing of voltage, frequence and processing time and the wear is found to be less in the Ti-addited coatings.