Abstract:
Ni and n-SiO2/Ni coatings were prepared by brush plating with direct current, pulse current and pulse reverse current. SEM, AFM, TEM and XRD methods were applied to investigate the morphology, microstructure and grain size of the coatings. The results showed that the surface morphology of the brush coatings is a cellular-like structure and the grain size is all in nano scale. It indicated that brush plating is an old but still unknown technique for the nano-technology. In composite brush plating process, the existence of nano particles and pulse reverse current increase the nucleation rate and restrain the grain growth, which results in the refinement of nanocrystalline. The hardness of the coatings shows a good relation with its grain size.[著者文摘]
Key words:
Brush plating; nanocrystalline; strengthening mechanism
采用直流、脉冲和脉冲换向电流制备了Ni和n—SiO2／Ni电刷镀镀层，利用SEM、AFM、TEM和XRD等技术对镀层的表面形貌、显微组织和晶粒尺寸等进行了分析测量。结果表明，电刷镀层表面呈胞状组织，镀层的晶粒尺寸均在纳米量级，说明电刷镀技术是一个古老而未被认识的纳米技术；复合电刷镀过程中纳米颗粒的作用及脉冲换向电流，能进一步提高镀层的形核率及抑制晶粒的生长，从而减小纳米晶的尺寸。镀层的硬度与纳米晶的尺寸有很好的对应关系