n-ZrO_2/Ni复合电刷镀层的微动磨损行为

Fretting Wear Behavior of n-ZrO_2/Ni Composite Coating Prepared by Electro-brush Plating

利用电刷镀技术制备n-Z rO2/N i复合镀层,研究复合镀层与GC r15配副从室温到500℃的微动磨损行为,探讨了复合镀层的微动磨损机理.结果表明:随着试验温度升高,由于磨损表面发生摩擦氧化反应,形成具有固体润滑作用的氧化物保护层,使得其摩擦系数逐渐降低,当试验温度为500℃时,氧化物保护层大面积脱落导致摩擦系数上升;复合电刷镀层的显微硬度随温度升高而显著下降,导致其抗磨损性能降低;复合电刷镀层在室温下的微动磨损失效机理主要以剥层磨损为主,在200℃以上主要为剥层磨损,并伴有一定程度的粘着磨损.

n-ZrO2/Ni composite coatings were prepared on 30CrMnSi steel substrate by electro-brush plating, and the content of n-ZrO2 particles （about 50 nm） in a nickel brush plating electrolyte was 20 g/L. Morphology and microhardness of the coating were examined using scanning electron microscope （SEM） and FIMT-3 sclerometer. Fretting wear behavior of the coatings against GCr15 under dry sliding up to 500 ℃ was investigated on PLINT test rig. Fretting wear mechanism of the coatings was discussed, based on morphological observation of the worn surface with SEM and elemental composition measurement with energy dispersive spectrometry （EDS）. It was found that friction coefficients of the coatings decreased with increase in testing temperature, which was attributed to solid lubrication of an oxide protective coating formed on the worn surface by way of tribochemical reactions, and when testing temperature was 500 ℃ friction coefficient increased due to delamination of protective oxide coating. Fretting wear resistance of the coatings decreased significantly with increase in testing temperature, resulting in obvious decrease of coating microhardness. SEM observation shows that predominant fretting wear mechanism of the coating at room temperature and above 200 ℃were delamination and combination of delaminating with adhesion respectively.