摘要
For the first time,functionally electroless nickel plated ZrO2(NCZ)graded Ni-NCZ composite coating has been successfully co-electrodeposited from a bath with gradually increasing of stirring rate.Studies showed that co-electrodeposition in a bath with stirring rate of250r/min results in the maximum co-electrodeposited particle content and the best particle distribution.To produce NCZ graded Ni-NCZ composite coating,the stirring rate was continuously increased from0to250r/min.The electroplated coating had a continuous gradient increasing of co-electrodeposited NCZ content from substrate towards the surface.The results showed that with increasing the co-electrodeposited NCZ particles content in Ni matrix,microhardness increases from interface towards the surface of the coating.Little crystallite size of Ni matrix and higher co-electrodeposited hard particles content were recognized as the reasons of microhardness increasing.Bend test revealed that the functionally graded composite coating shows more excellent adhesion to the substrate compared with the ordinary distributed Ni-NCZ on the same substrate.This result is attributed to lower mechanical mismatch between coating and substrate in the functionally graded composite coating with respect to the uniformly distributed one.The results of wear resistance measurements reveal that wear resistance of functionally graded Ni-NCZ is higher than that of ordinary distributed composite coating.
通过逐步提高搅拌速率,成功从电镀槽中共同电沉积化学镀镍ZrO_2(NCZ)功能梯度Ni-NCZ复合涂层。研究表明,在搅拌速度为250 r/min的电镀槽中,共同电沉积导致最大颗粒含量和最佳颗粒分布。为制备NCZ梯度Ni-NCZ复合涂层,搅拌速度从0不断增加至250 r/min。从基体到表面共沉积的NCZ含量持续增加。结果表明,随着镍基体中共同电沉积的NCZ粒子含量的增加,从界面到涂层表面显微硬度增加。镍基体较小的晶粒尺寸和较高的共同电沉积颗粒含量是显微硬度提高的原因。弯曲试验表明,与普通Ni-NCZ涂层相比,功能梯度复合涂层与基体具有更好的附着力,这一结果归因为功能梯度复合涂层与基体之间具有更好的机械匹配。耐磨测试结果表明,功能梯度Ni-NCZ复合涂层的耐磨性优于普通复合涂层。
