镁合金表面Ni-P/Ni镀层的制备与性能研究

Study on the Preparation and Properties of Ni-P/Ni Duplex Coating on the Surface Magnesium Alloys

在镁合金表面先化学镀Ni-P层,再电镀Ni,获得高耐蚀性Ni-P/Ni镀层,并用静态腐蚀浸泡法研究了化学镀时间和电镀时间对所得镀层在5%NaCl溶液中的耐蚀性能的影响。结果表明,先化学镀40 min,再电镀15 min所得的Ni-P/Ni镀层具备高耐蚀性能,电化学测试结果表明,此种镀层在酸性和碱性溶液中都具有较好的耐蚀性能。在200℃热处理24 h后,Ni-P/Ni镀层的耐蚀性提高,同时外层Ni层的显微硬度从HV460增大到HV550。镀层侧面的SEM照片显示,镀层均匀致密,与基体结合良好,化学镀层与电镀层之间没有明显的界限。

The high corrosion resistance Ni-P/Ni duplex coating was deposited on the surface of magnesium alloys by electroless depositing Ni-P and following electrodepositing Ni. The effect of electroless deposition and electrodeposition time on the corrosion resistance of the duplex coating was investigated by static corrosion immersion in the 5 % NaCl aqueous solution. the results indicate that only the electroless deposition time no less then 40 min, the duplex coating get high corrosion resistance. The observations of linear sweep polarization curve experiments indicate that both in the acidic solution and alkalic solution the duplex coating has good corrosion resistance. After heat treatment at 200 ℃ for 24 hours the corrosion resistance of the Ni- P/Ni duplex coating increases and the microhardness of the eletrodeposition exterior Ni layer increases from HV460 to HV550. The SEM observation of the cross section of the duplex coating indicates that the coating is connected well to the magnesium substrate and there isn＇t obviously interface between the Ni-P layer and Ni layer.