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

Defect free coatings, made of Tribaloy T-400 powder, deposited by laser cla dding on iron and nickel based substrates are described. The proper selecti on of the cladding process parameters allowed us to get coatings with low d ilution of the base material. Cross-sections of such coatings have been exa mined to reveal their microstructure using optical, scanning electron and t ransmission electron microscopy, chemical analysis (EDS microanalysis), pha se composition (XRD), hardness and microhardness testing methods. Compared with other deposition techniques the microstructure of the laser coatings s howed a high degree of refinement and chemical homogeneity. Grain coarsenin g was observed in the heat-affected zones and was explained as being due to the overlapping of subsequent tracks during the coatings deposition. The e rosive wear resistance of the coatings has been investigated. In general, t he laser deposited coatings turned out to be susceptible to extensive erosi ve wear. This effect was explained by lack of feasibility of the coated mat erial to plastic deformation during erosion. (C) 2000 Elsevier Science S.A. All rights reserved.