STUDY OF LASER CLADDING OF COMPOSITE COATINGS

Laser cladding is often used for manufacturing of protective coatings due to limited heat input. The thermal conditions are decisive for the microstructure and thus the properties. In this study Ni-based powder with addition of WC particles was used laser cladding with the TruDisk 3302 laser. Tests were conducted at different energy input (heat transfer efficiency not considered). Powder was fed directly into the melt pool by a single coaxial nozzle set in front of the melt pool. The influence of basic laser cladding parameters on the geometry, microstructure and hardness was determined. The heat input of laser cladding has significant effect on chemical and phase composition, as well as microstructure. The obtained coatings have typical composite structure with NiCr metallic matrix and WC carbides. The lower energy input of laser cladding is beneficial providing limited penetration depth, dilution, and preferable distribution and high share of tungsten carbides. However, too low energy input at the chosen technological conditions will lead to the lack of fusion. The share of carbides on cross section of the coatings produced at minimum heat input is over 50%, while for the maximum heat input the share is below 20%.