Binary WC- and Cr3C2-containing hardmetal compositions for thermally sprayed coatings

Compositions of thermally sprayed hardmetal coatings for wear protection are based on the hard materials WC and Cr3C2 with Co and Ni as the most important binders, which are often alloyed with Cr. There are a few commercial compositions containing WC and Cr3C2 together, which have a high potential for the improvement of coating properties, in particular for service in corrosive environments and high temperature applications. However, the combined application of WC and Cr3C2 in the coating compositions leads to very complex reactions between these components both during feedstock powder preparation and the spray process. This contribution summarizes the knowledge about the interactions of WC and Cr3C2 for the most important commercially available compositions: WC-10Co-4Cr, WC-20'CrC'-7Ni, 45Cr3C2- 37WC-18NiCo. These three compositions show remarkable differences of the interaction between WC and Cr3C2 and the coating properties.