激光预处理基体细化铬层晶粒的电镀机理研究

为了揭示激光淬火预处理钢基体细化镀铬层界面晶粒的电镀机理，采用理论和试验相结合的方法进行了理论分析和试验验证。用化学腐蚀法制备了铬层/激光离散预处理基体界面的两侧（铬层界面与基体界面），利用扫描电镜研究了铬层界面晶粒形貌，利用激光粗糙度仪测量了基体界面粗糙度；借助电镀理论构建了以过电位为中间变量的铬层界面晶粒尺寸和基体界面粗糙度关系分析模型；取得了粗糙度与晶粒尺寸呈正比的试验结果和粗糙度与晶粒尺寸呈正比的理论关系，得到了淬火预处理钢基体细化镀铬层界面晶粒的电镀机理。结果表明，激光淬火预处理钢基体得到的较小粗糙度可以提高过电位，过电位的提高减小了铬层界面晶粒尺寸。这一结果对进一步解释激光淬火预处理可以提高基体/铬层界面结合强度是有帮助的。

Study on the plating mechanism of grain refinement of Cr-plating coating by laser pretreatment substrate

In order to reveal the plating mechanism that the steel substrate pre-treated by laser quenching could refine the grain of the Cr-plating coating interface, theoretical analysis and experimental verification were carried out. Both sides of the interface between laser discrete pre-quenching substrate and Cr-coating were prepared by chemical etching method: Cr-plating coating interface and substrate interface. The grain morphology of Cr-plating coating interface was researched by scanning electron microscope and the roughness of substrate interface was measured by laser roughness instrument. Based on plating theory, the analytical model of the relationship between the grain size and the roughness was developed with the help of the over-potential. The test and theoretical results indicated that the roughness was proportional to the grain size. The results show that the plating mechanism of grain refinement of Cr-plating coating by laser pretreatment substrate is that the smaller roughness could increase the over potential, which is obtained by laser pre-quenching substrate. The increase of over-potential reduces the grain size. The result is helpful for further analysis of laser pre-processing substrate to improve the interfacial bonding strength.