Rare Earth-Enhanced Laser Cladding Metal-Based Coatings: A Review.

Laser cladding technology is a widely applied surface modification technique; but its inherent process characteristics render it susceptible to cracking. The addition of rare earth oxides has proven to be an effective approach for curbing crack formation and enhancing the comprehensive performance of the coating. This review summarizes the mechanisms by which rare earth additives improve the coating microstructure, molten bath behavior, and interfacial bonding strength, including adjusting surface tension, purifying the molten bath, and forming interatomic chemical bonding. The addition of rare earth oxides significantly improves the forming quality of materials, which contributes to a finer and more uniform microstructure and directly enhances material hardness and resistance to plastic deformation, thereby altering wear behavior and improving wear resistance. The increased hardness provides better support for the surface oxide film, while the improved microstructure mitigates galvanic corrosion and intergranular corrosion susceptibility, leading to enhanced corrosion resistance. In addition, the article incorporates relevant quantitative analysis to provide a reference basis for the type selection, content optimization, and particle size selection of rare earth additives. This article provides a coherent framework for understanding how the addition of rare earths transfers its effects from the process to the performance. However, the industrial application of rare earth oxide laser cladding faces key bottlenecks such as additive deactivation under extreme conditions, threshold effects, nano-agglomeration, and cost constraints.