水环境下的激光熔覆技术是保证海洋工程装备水下关键部件服役可靠性及安全性不可或缺的技术手段，也是提高我国海洋工程装备整体水平的重要途径。然而，目前水环境下金属基激光熔覆涂层的成形机理及摩擦学性能的研究一直停滞不前，国内外可供参考的研究成果非常少。因此，本项目拟针对海洋工程装备水下易损部件在线维修的迫切需求，开展水环境下金属材料激光熔覆成形及熔覆层摩擦学的机理研究。重点分析激光/水/材料之间相互作用下的熔覆层传质过程，明确氢、氧、氯、硫等有害杂质在熔覆层中的扩散机制，分析水下激光熔覆过程中残余应力产生及演变机制，阐明水环境中多物理场耦合下的组织演变规律和气孔、裂纹等缺陷形成机理，揭示水环境中多因素耦合作用下的熔覆层磨损失效机理及摩擦学性能关键控性因素，构建较为完善的水下金属材料激光熔覆成形机理及熔覆层摩擦学行为理论体系，为海洋工程关键装备的水下在线维修提供理论指导。

The laser cladding technology in water environment is the indispensable method to secure the reliability and safety of key components of ocean engineering equipment and it is also a important way to improve integral level of national ocean engineering equipment.However, present study of the forming mechanism and tribological properties of metal laser cladding coating is at a standstill and there are limited foreign literatures that could be used as guidance. Therefore, this project focus on the urgent demand of online maintenance of vulnerable underwater components of ocean engineering equipment and carries out the study of laser cladding formation and tribological mechanism under water environment. This study is to reveal the cladding coating’s mass transfer mechanism between laser, water and materials, confirming the diffusion mechanism of H, O, Cl, S etc. detrimental impurities in cladding coating. Moreover, it also reveals the formation and evolution mechanism of residual stress in laser cladding process, illustrating the evolution regular of organization and forming mechanism of pores and crack etc. defects under multi-physics coupling underwater circumstance, revealing key controlling factors of wear failure mechanism and trobological properties under underwater multifactor coupling environment. Establishing theory system of forming mechanism and tribological behaviors of underwater metal laser cladding, supply the theoretical guidance of on-line maintenance of ocean engineering equipment.