PHASE DISTRIBUTION AND FORMATION MECHANISM OF CERAMIC COATINGS FORMED BY MICROARC OXIDATION(MAO)ON AI ALLOY
XUE Wenbin; DENG Zhiwei; LAI Yongchun; CHEN Ruyi (Beijing Normal University)
The phase distribution of ceramic coatings formed by microarc oxidation on LY12 Al alloy was investigated by XRD method, the formation mechanism was also discussed. The results show that the ceramic coatings mainly contain a--A12O3, γ-Al2O3 phases, the α-Al2O3 content gradually increases from external layer to internal layer of coatings. The external layer of coating is mainly composed of γ-Al2O3 phase, and its content is merely independent on the oxidation time. The difference of α-Al2O3 and γ-Al2O3 contents between external layer and internal layer of coating is mainly caused by the change of cooling rate of molten alumina in microarc zone.