【摘要】 以航空零件常用材料300M钢为基材,采用柔性挤压电镀(也称摩擦辅助电镀)工艺制备无裂纹的硬铬镀层。镀液组成和工艺条件为:铬酸酐250 g/L,硫酸根离子2.5 g/L,镀液流速3.2 L/min,极间距45mm,占空比80%或85%,阴极转速300r/min或325 r/min,电流密度30~60 A/dm~2,频率5~20 kHz,温度35~55℃,时间3 h。研究了电流密度、温度及脉冲频率对电流效率的影响,并与传统电镀硬铬工艺进行对比。结果表明,柔性挤压电镀铬的电流效率随电流密度升高而升高,随温度升高而降低,随脉冲频率的变化不大。采用本工艺制备的铬镀层表面光亮度接近镜面,致密、均匀,无裂纹。但柔性挤压电镀铬工艺的电流效率略低于传统电镀铬工艺。更多还原

【Abstract】 A crack-free hard chrome coating was prepared by flexible extrusion plating(also termed friction-assisted plating)using 300 M steel,a commonly used material for aeronautical parts,as the substrate.The bath formulation and process conditions are as follows:chromium anhydride 250 g/L,sulfate ions 2.5 g/L,flow rate of bath 3.2 L/min,distance between electrodes 45 mm,duty cycle 80%or 85%,rotation rate of cathode 300 or 325 r/min,current density 30-60 A/dm~2,frequency5-20 kHz,temperature 35-55℃ and time 3 h.The effects of current density,temperature and pulse frequency on the current efficiency were studied and compared with the traditional hard chrome plating.The results showed that the current efficiency of flexible extrusion chrome plating is increased with increasing current density,decreased with increasing temperature,and changed slight with increasing pulse frequency.The chrome coating prepared by the given process features a compact,uniform and crack-free surface with a brightness near to that of mirror.However,the current efficiency of the flexible extrusion chrome plating is slightly lower than that of the traditional chrome plating.更多还原