Laser cladding and erosive wear of Co-Mo-Cr-Si coatings

Defect free coatings, made of Tribaloy T-400 powder, deposited by laser cladding on iron and nickel based substrates are described. The proper selection of the cladding process parameters allowed us to get coatings with low dilution of the base material. Cross-sections of such coatings have been examined to reveal their microstructure using optical, scanning electron and transmission electron microscopy, chemical analysis (EDS microanalysis), phase composition (XRD), hardness and microhardness testing methods. Compared with other deposition techniques the microstructure of the laser coatings showed a high degree of refinement and chemical homogeneity. Grain coarsening was observed in the heat-affected zones and was explained as being due to the overlapping of subsequent tracks during the coatings deposition. The erosive wear resistance of the coatings has been investigated. In general, the laser deposited coatings turned out to be susceptible to extensive erosive wear. This effect was explained by lack of feasibility of the coated material to plastic deformation during erosion. (C) 2000 Elsevier Science S.A. All rights reserved.