电解液pH对钛合金微弧氧化陶瓷膜的影响

Effects of pH of Electrolyte on Ceramic Micro-arc Oxidation Coating on Titanium Alloy

采用微弧氧化法在不同pH的电解液中于钛合金表面制备了二氧化钛陶瓷膜,借助SEM、XRD分析了膜层的形貌和物相组成,研究了电解液pH与微弧氧化过程中电流密度、膜层形貌和膜层中钙磷含量的关系,以及电解液pH对钙磷元素进入膜层方式的影响。结果表明:陶瓷膜呈粗糙多孔的表面结构,主要由锐钛矿和金红石相组成;电流密度随氧化时间的延长先增大后减小,同一时刻电流密度随电解液pH的增大而增大;随着电解液pH的增大,膜层中钙的原子分数逐渐增加,磷的原子分数先减小后增加,钙元素主要依靠微弧氧化过程中的高温烧结进入膜层,磷元素依靠静电引力和高温烧结的共同作用进入膜层。

A titanium dioxide ceramic film was prepared on titanium alloy surface by micro-arc oxidation （MAO） in electrolyte of different pH. The surface morphology and film composition were studied by scanning electron microscopy and X ray diffractometer, and the relation among of electrolyte pH and current density, surface morphology of film and atom fraction of Ca and P were studied. The way of Ca, P elements getting into film being changed by electrolyte pH was also studied. The results show that a porous ceramic film containing calcium and phosphate was acquired. The current density first increased and then decreased with the increase of the oxidation time, and it increased with the increase of the electrolyte pH at the same time. The atom fraction of calcium in the film increased as the electrolyte pH increasing, however the atom fraction of phosphate decreased first and then increased. Calcium was mainly through high temperature sintering during micro-arc oxidation process into the film, but the phosphate element was through the static electricity and high temperature sintering working together.