热处理工艺对Ni-Cu-P化学镀层耐蚀性的影响

Effect of Heat Treatment Process on Corrosion Resistance of Electroless Ni-Cu-P Coating

为进一步提高Ni-Cu-P化学镀层的耐蚀性,设计了3种不同温度及保温时间的热处理工艺对镀层进行热处理。通过XRD分析了镀态及热处理态镀层结构的变化,通过2273电化学工作站测试了它们在3.5%Na Cl溶液中的极化曲线和交流阻抗。结果表明:热处理后由于Ni-Cu固溶体及Ni3P相的析出,使得热处理态镀层在腐蚀介质中具有更低的腐蚀电流密度和更高的电荷转移电阻,且300℃保温30 min的热处理工艺处理的镀层耐蚀性最佳。

In order to improve the corrosion resistance of electroless Ni-Cu-P coating, coated samples were isothermally heat treated at three kinds of different conditions. Changes of phase transformation and composition behavior of coating as-deposited and heat-treated were analyzed by XRD. The dynamic potential polarization curves and electrochemical impedance spectroscopy of those coatings in 3.5% NaCl solution were tested by means of 2273 electrochemical testing.Results show that heat treatments significantly improve the corrosion resistance of these coatings, which is attributed to Ni-Cu solid solution and Ni3P phase precipitates form coatings; Heat treated coatings have smaller corrosion current density and higher charge-transfer resistance than as-deposited coating in corrosive medium, The best corrosion resistance property is obtained after heat treatment temperature at 300 ℃ for 30 min.