Effect of rare earth oxide additive in coating deposited by laser cladding: A review

In this paper, the effect of rare earth oxide additive on coating material deposited by laser cladding process on various engineering materials has been discussed. The purpose of rare earth oxide additive in the coating composition is to improve the various properties like mechanical, tribological, and chemical properties. The main rare earth oxides are La2O3, CeO2 and Y2O3, which are generally used in laser cladded coatings. The limited amount of addition of these rare earth oxide compound may leads to improvement in hardness, wear and corrosion resistance of coating. The attractive properties of rare earth oxide is grain refinement, conversion of coarse structure to fine dendritic structure, creating grain boundary movement hindrance of dislocation in the material which leads to its application as nutrients in the coating material. The main purpose of coating is to enhance the surface properties of material like hardness, corrosion resistance and wear resistance. When rare earth oxide are added to the coating then it creates extra enhancement in the above properties. The laser cladding is widely used in modern manufacturing technology due to its very attractive properties like good metallurgical bonding with substrate, less dilution, minimum distortion, less heat affected zone and fast solidification and high cooling rate. In this review article the coating developed by laser cladding on various conventional engineering materials like ferrous materials, magnesium alloys, titanium alloys, aluminium alloys and nickel based super alloys with rare earth oxide addition are described.