搅拌摩擦加工修复激光钴基涂层/铜基体弱结合界面及结合强度提升基础研究

结晶器铜板表面激光熔覆钴基耐磨涂层与铜基体界面存在弱结合缺陷，成为长期困扰激光表面改性的重要难题。针对激光涂层弱结合界面修复问题，本项目打破传统思路，提出采用搅拌摩擦加工方法，利用其大塑性流动场的热力耦合效应，将激光钴基涂层/铜基体弱结合界面调整为“穿插互锁（机械结合）”与“原子扩散（冶金结合）”两种尺度结合，同时使界面两侧组织纳米化，从而提升界面结合性能。本项目在前期已初步获得搅拌摩擦制备穿插互锁涂层经验基础上，凝练出以下科学问题：一，搅拌摩擦塑性流动场诱导界面穿插互锁形成机理及影响规律；二，搅拌摩擦塑性流动场增强界面原子扩散动力学；三，界面穿插互锁、界面扩散、纳米晶形成对界面剪切强度影响模型。以塑性力学、扩散动力学等理论为指导解决以上科学问题，获得“塑性流动场-界面穿插互锁与原子扩散-界面剪切强度”定量关系，从而实现界面多尺度结合与强化精确调控，为铜结晶器激光表面改性提供科学支撑。

The weak bonding interface that usually existed between laser cladding Co-base coating and crystallizer copper plate, is a significant problem that plagued surface modification field for a long time. Aimed at the repairing the weak interface, this project breaks traditional thought and proposes the friction stir processing (FSP) method to repair the interface by its thermal mechanical coupling effect of severe plastic flow field, so as to transform the weak interface to the strengthened interface with interlocking bonding and atom diffusion bonding. The former is mechanical bonding and the latter is metallurgical bonding. Simultaneously, the microstructures of both coating and substrate are refined to nanograins. Thus, the coating bonding strength could be enhanced. Based on the earlier-stage work of producing interlocking coating, this project proposes the following scientific problems: first, the mechanism and influencing principle of FSP plastic flow inducing interlocking interface; second, kinetics of FSP plastic flow enhancing the atom diffusion of interface; third, influencing model between interlocking interface, atom diffused interface, nano-crystallization and interface shear strength. This project will use the theories of plastic mechanics and diffusion kinetics to solve the scientific problems, so as to obtain the relation model of “plastic flow field-interface interlocking and diffusion-interface shear strength”, by which the precise technical control of interface multi-scales bonding and strengthening can be realized. This project could provide scientific basis for surface modification of copper crystallizer.