电沉积铜–镍–锡–聚四氟乙烯复合镀层及其性能

Electrodeposition of copper–nickel–tin–polytetrafluoroethylene composite coating and its properties

针对Cu–Ni–Sn合金自润滑性能差的问题,向Cu–Ni–Sn合金镀液中加入聚四氟乙烯(PTFE)乳液,采用电沉积法在45钢表面制备了Cu–Ni–Sn–PTFE复合镀层。镀液组成和工艺条件为:氰化亚铜35 g/L,游离氰化钠10 g/L,锡酸钠10 g/L,氯化镍15 g/L,蛋氨酸20 g/L,甲基磺酸18 g/L,60%PTFE乳液5~15 m L/L,电流密度1 A/dm^2,温度50~60°C,pH 10,时间2 h。考察了镀液PTFE含量对镀层的耐磨性、显微硬度、结合力、PTFE含量以及外观的影响,表征了Cu–Ni–Sn–PTFE复合镀层的形貌、结构和成分。随着镀液PTFE含量的升高,镀层的耐磨性改善,但显微硬度和结合力下降,厚度和PTFE含量则先升后降。镀液中PTFE的最佳添加量为10 m L/L,此添加量下所得Cu–Ni–Sn–PTFE复合镀层的综合性能最佳。

In order to solve the problem of poor self-lubrication of Cu–Ni–Sn alloy, Cu–Ni–Sn–PTFE composite coating was prepared on the surface of 45 stainless steel from a Cu–Ni–Sn plating bath containing polytetrafluoroethylene（PTFE, added in the form of emulsion） by electrodeposition. The bath composition and process conditions are as follows： cuprous cyanide 35 g/L, free sodium cyanide 10 g/L, sodium stannate 10 g/L, nickel chloride 15 g/L, methionine 20 g/L, methanesulfonic acid 18 g/L, 60% PTFE emulsion 5-15 m L/L, current density 1 A/dm^2, temperature 50-60 °C, pH 10, and time 2 h. The effects of PTFE content in bath on the wear resistance, microhardness, adhesion strength, PTFE content, and appearance of the Cu–Ni–Sn–PTFE composite coating were studied. The morphology, microstructure, and elemental composition of the Cu–Ni–Sn–PTFE composite coating were characterized. With increasing PTFE content in bath, the wear resistance of coating improves, microhardness and adhesion of coating decrease, thickness and PTFE content of coating increase firstly and then decrease. The Cu–Ni–Sn–PTFE composite coating obtained at an optimal dosage（i.e. 10 m L/L） of PTFE features the best comprehensive performance.