Biodegradation and hydrophilisity of silicate grown films on AZ31 magnesium alloy by micro-arc oxidation

In this study taguchi design of experiments has been used for optimizing the parameters of the micro arc oxidation process on AZ31 magnesium alloys. As a consequence by evaluation the analyze of variance of the experimental data''s (ANOVA)، the effectiveness of different factors such as current density، Na2SiO3 and NaF concentration and time on two different responses namely resistance polarization and hydrophilisity (contact angle) of coating was investigated. The statistical results showed that for gaining the greatest polarization resistance and the lowest water contact angle، two factors of Na2SiO3 concentration and time had the most effect respectively. The effect of Na2SiO3 concentration on polarization resistance can be attributed to variation of Mg2SiO4 and MgSiO3 phases in the coating. Moreover factor of time can affect on hydrophilisity of specimens by altering the roughness and Mg2SiO4 containing of the coating، so that by increasing the time، contact angle will be decreased first and then it will be increased.