脉冲电沉积纳米镍-碳化硅复合镀层的性能

Properties of nickel-silicon carbide nanocomposite coating prepared by pulse electrodeposition

分别采用直流(DC)和换向脉冲电流(PRC)电沉积法制得纳米Ni-SiC复合镀层。采用X射线衍射仪、扫描电镜、能谱仪对比研究了纯Ni镀层和Ni-SiC复合镀层的微观结构、宏观残余应力、表面形貌及成分。用浸泡法研究了不同镀层在3.5%(质量分数)NaCl和10%(体积分数)H2SO4溶液中的腐蚀行为。结果表明,脉冲电沉积能改变镀层的微观结构,有效提高镀层硬度,降低宏观残余应力。脉冲电沉积所得到的纯Ni镀层和纳米Ni-SiC复合镀层在3.5%NaCl及10%H2SO4溶液中的耐蚀性均优于直流镀层。脉冲镀层在3.5%NaCl溶液中受腐蚀很轻,主要腐蚀形态为点蚀,而在10%H2SO4溶液中,SiC粒子作为增强相使镀层的耐腐蚀性进一步提高。

Nano Ni-SiC composite coatings were prepared by direct current （DC） and pulse reverse current （PRC） electrodeposition respectively. The microstructure, macro- residual stress, surface morphology, and chemical composition of pure Ni coatings and Ni-SiC composite coatings were comparatively studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The corrosion behavior of different coatings was studied by immersion method. The results showed that PRC technique can change the microstructure of coatings, improve the hardness, and lower the macro-residual stress of coatings. Both PRC pure Ni coating and PRC Ni-SiC composite coating have better corrosion resistance in 3.5% （mass fraction） NaCl and 10% （volume fraction） H2SO4 solutions than DC coatings. PRC coating suffers pitting corrosion slightly in 3.5% NaCl solution. In 10% H2SO4 solution, SiC particles as reinforcement further improve the corrosion resistance of PRC coatings.