Improvement in the properties of plasma-sprayed chromium carbide coatings using nickel-clad powders

In this paper, electroless plating was used to prepare Ni-clad Cr3C2 powders with different nickel contents, and plasma spraying was carried out to deposit the corresponding coatings. The deposited coatings were then compared with coatings sprayed using mechanically blended Cr3C2-NiCr powders in terms of microstructure, phase composition, mechanical and tribological properties. The results obtained indicated that the elemental nickel in the coatings using the Ni-clad powders was better distributed than that using the mechanically blended Cr3C2-NiCr powders; and the free carbon content was also lower in the former coatings than in the latter coatings. Comparing properties of the different coatings with each other, it was found that the Ni-clad Cr3C2 powders obviously improved not only the elastic modulus, fracture toughness and wear resistance of chromium carbide coatings, but also the Weibull modulus of the microhardness and elastic modulus. The above results may be ascribed to an increase in the real contact and in the bonding strength between the lamellae of the coatings. (C) 2000 Elsevier Science S.A. All rights reserved.