Development and characterization of composite Ni-Cr + WC laser cladding

摘要

To increase the life of mechanical parts submitted to severe oxidizing and abrasive environments, specific coatings are frequently used. Since two decades, with the rapid development of lasers, power lasers have been used to produce high quality coatings. Metal matrix composite (MMC) coatings composed of nickel and tungsten carbides (Ni-WC) are frequently used to solve problems of reduced life under severe abrasive conditions. Comparative abrasive tests between laser cladding and conventional hardfacing have been performed following the ASTM G-65 standard test method and noticeable increased life (up to six times) has been obtained for the laser cladding. This better resistance to abrasion results from the low dilution and the rapid solidification rate obtained with the laser cladding. As a consequence, for MMC coatings reinforced with WC particles, laser cladding exhibits higher WC volume content and finer microstructure. For applications where oxidation and abrasion resistances are needed, special metal matrix composite such as nickel-chromium alloy + WC particles have been developed. Nickel chrome matrixes with various WC volume content claddings have been produced on standard steel. The effects of the process parameters on the cladding quality are discussed and microstructure observations are presented.