Effect of micro--arc oxidation current density on the structure of the coatings by a compound oxidation preparation
电流密度对复合氧化法制备涂层结构的影响

Influence of the current density on the structure and properties of porous titania coatings prepared by the compound process (pre-oxidation and micro-arc anodic oxidation) was studied by means of SEM, EDS, X-ray diffraction and micro-hard meter. The morphologies, phase structures, element compositions and micro-hardness were tested. The results show that there are obvious effects of the current density on the structure and properties of titania coatings. The coatings are mainly composed of anatase when the current density is kept in a low level (20 mA/cm2). When the current density increases, anatase decreases and rutile increases. The pores diameter, surface roughness and hardness of the coatings increase, and the molar ratios of Ca/P are changed at the same time. When the current density are 20, 40, 60, 80 and 100 mA/cm2, the molar ratios of Ca/P are 1.22, 1.60, 1.89, 2.01, 2.12, respectively. The porous titania coating containing Ca and P with preferable microstructure and property can be prepared when the current density is at 40 mA/cm2.