镍基纳米陶瓷颗粒脉冲电刷镀复合层的形貌及磨损性能

Morphology and Tribological Behavior of Ni/n SiO_2 Composite Coating Prepared by Pulse Current Brush Plating

为了探讨不同电源电刷镀层的形貌及耐磨性,用直流电源和不同电参数脉冲电源制备了镍基纳米陶瓷颗粒(Ni/n SiO2 )复合镀层,用Quanta200型扫描电镜、T 11球盘摩擦磨损试验机对其表面形貌、磨损性能进行了分析比较。结果表明:脉冲电刷镀Ni/n SiO2复合镀层比直流Ni/n SiO2复合镀层表面更平整,镀层晶粒团更加细小、孔隙率更低、耐磨性更高。纳米颗粒的复合提高了复合镀层的强度,从而避免了快镍镀层磨损中柱状晶脆性断裂磨损方式,提高了复合镀层的耐磨性;脉冲电源通过改善镀层的致密程度,减小了粘着磨损中微凸体的接触应力,使脉冲刷镀层的耐磨性优于直流刷镀层。

Nanostructured Ni/n SiO_2 composite coating was prepared by brush plating with direct and pulse current. The morphology of the Ni/n SiO_2 composite coating was observed using a Quanta 200 scanning electron microscope. The wear resistance of the Ni/n SiO_2 composite coating was evaluated using a T 11 ball on disk friction and wear tester. It was found that the incorporation of the SiO_2 nanoparticles contributed to preventing the fracture of the columnar crystal in rapid nickel plating and hence increasing the strength and wear resistance of the Ni/n SiO_2 composite coating. The composite coating prepared by the pulse current plating was smoother and had smaller columnar crystalline size, lower porosity, and higher wear resistance than the one prepared by the direct current plating. This was because the pulse current helped to increase the density and strength of the composite coating, which in turn contributed to preventing the composite coating from brittle fracture and decreasing the contact stress on the asperities during the sliding process.