材料期刊网

采用恒流和梯度电流两种方式对TC4钛合金进行微弧氧化，微弧氧化液组成和工艺参数为：Na2SiO316 g/L，(NaPO3)68 g/L，NaF 2 g/L，频率500 Hz，占空比10%。研究了不同电流模式下电压随微弧氧化时间的变化。对比研究了两种电流模式下所得微弧氧化膜的表面形貌、厚度、粗糙度、显微硬度等性能。结果表明，恒流模式下，随电流密度升高，氧化膜层的终止电压、厚度、粗糙度和表面微孔直径增大，显微硬度先增大后减小；与恒流模式膜层相比，梯度电流模式下所得氧化膜层较厚，粗糙度较低，硬度高，表面微孔直径较小。较适宜的恒流电流密度和梯度电流密度分别为10 A/dm2和15-5 A/dm2，而后者所得膜层的综合性能优于前者所得膜层。

The micro-arc oxidation of TC4 alloy was conducted in a bath containing Na2SiO3 16 g/L, (NaPO3)6 8 g/L, and NaF 2 g/L at frequency 500 Hz and duty cycle 10% under constant current and gradient current modes, respectively. The variation of voltage with micro-arc oxidation time under different current modes was examined. The surface morphology, thickness, roughness, and microhardness of the micro-arc oxidation films obtained under different current modes were comparatively studied. The results showed that with the increase of current density at constant current, the cut-off voltage, thickness, roughness, and micropore diameter on the surface of micro-arc oxidation film are increased, while its microhardness is increased initially and then decreased. The oxidation film obtained at gradient current has higher thickness, lower roughness, higher microhardness, and smaller micropore diameter than that obtained at constant current. The suitable current density is 10 A/dm2 for constant current mode and from 15 to 5 A/dm2 for gradient current mode. The comprehensive performance of the film obtained at 15-5 A/dm2 is better than that obtained at 10 A/dm2.