Research status of laser cladding metal-based coatings with rare earth addition

Fabrication of surface strengthening coating using laser cladding is one of the important ways to improve the materials service performance.According to the requirement of service environment,the performance can be improved and service life can be elongated of the work pieces by regulating the compositions and microstructures of cladding coatings through adjusting the laser cladding parameters.Recent years,doping rare earth has been one of the research hotspots in laser cladding field.Rare earth elements have special electronic structure,which can purify the alloy solution and refine the grains.The appropriate addition of rare earth can effectively reduce the dilution rate,refine the grain size,decrease the porosity and release the residual thermal stress,thus reducing the crack sensitivity of the cladding layer.Therefore,the coatings with rare earth have better strength,toughness,corrosion resistance and wear resistance.Designing metal-based coatings with different types of rare earth addition and combining with appropriate laser cladding parameters are expected to be an ideal method for surface strengthening in extreme environment.In this paper,the effects of three common rare earth oxides(lanthanum oxide,cerium oxide and yttrium oxide)are summarized,and the latest research results of rare earth reinforced metal-based laser cladding coatings are introduced detail,and the crucial problems to be solved in the field of surface engineering and the future development direction are prospected.