The effect of SiO₃^2- on micro-arc oxidization ceramic layer of TiAl alloy

The micro-arc oxidization is an efficient and pollution-free technique of surface processing and can form in situ a ceramic layer on the surface of nonferrous metal. In this paper, the micro-arc oxidization ceramic layer was formed on the surface of TiAl alloy by using a self-designing pulse power supply equipment of micro-arc oxidization. The oxidation dynamics of the ceramic layer on the surface of TiAl alloy was studied in the cycle high temperature condition and the experimental results show that the oxidation dynamics curve of TiAl alloy micro-arc oxidization ceramic layer submitted a parabolic function, which indicates that the ceramic layer can protect the TiAl alloy. Moreover, the effect of SiO₃^2- on the characteristics of the ceramic layer was also studied, the results show that the working temperature with a micro-arc oxidization ceramic layer can be increased to 1273 K after adding SiO₃^2- in the solution of the micro-arc oxidization. Analyzing by SEM and XRD test, the TiAl alloy ceramic layer contained 80 percent Al₂TiO₅, 11 percent TiO₂ and 9 percent SiO₂, which indicates that the addition of SiO₂ can effectively restrain the decomposition of Al₂TiO₅ at high temperature and thus significantly increase the anti-oxidation of the TiAl alloy.