镁合金表面Ni-P-纳米SiC复合化学镀层的耐腐蚀性能

Corrosion Resistance of Electroless Ni-P/Nano-SiC Composite Coating on Magnesium Alloy

为了提高AZ91D镁合金的应用性能,将纳米SiC引入Ni-P镀液,采用化学镀的方法制备了Ni-P-纳米SiC复合镀层,研究了Ni-P-纳米SiC镀层的孔隙率、盐雾性能以及阳极极化曲线,并与Ni-P化学镀层的耐蚀性进行了对比。结果表明:Ni-P-纳米SiC镀层均匀、致密,纳米SiC在镀层表面呈弥散分布;当纳米SiC浓度为4g/L时,复合镀层的孔隙率最小,为1个/cm,耐蚀时间(90h)明显长于Ni-P镀层(60h),腐蚀电位为-0.58V,略高于Ni-P镀层(-0.59V)。

Ni-P/nano-SiC composite coatings were prepared on Mg alloy substrate(AZ91D) by electroless plating.The porosity and anodic polarization curves of the coatings were measured,and the corrosion resistance of the composite coatings was compared with that electroless Ni-P alloy coating by making use of salt-spray tests.Results indicate that the Ni-P/nano-SiC composite coatings are uniform and compact,and nano-SiC particles are dispersively distributed on the coating surface.The composite coating obtained from the plating bath containing 4 g/L SiC had the smallest porosity and anticorrosion life of 90 h,which was much longer than that of electroless Ni-P coating(60 h).Besides,the composite coating had a corrosion potential of -0.58 V,which was slightly higher than that of Ni-P coating(-0.59 V).