Composition and structure of ceramic coatings prepared on pure titanium by alternating-current microarc oxidation

摘要

A ceramic oxide coating of 30um was prepared on TA2 pure titanium by alternating-current microarc oxidation in aluminate solution. Its microstructure and phase component were characterized by scanning electron microscopy, X-ray diffractometry, Raman spectroscopy. The Al, Ti, O concentration profiles across the coating were determined by energy dispersive spectroscope. The coating contains two layers, an outer layer and an internal layer. The outer layer is composed of a large amount of TiAl_2O_5 and a little rutile type TiO_2 compounds. But the rutile content in the inner layer is much higher than in the outer layer while the TiAl_2O_5 content decreases obviously in the inner layer. All of these oxides derive from a rapid solidification of the local molten coating in microarc discharge zone.