Microstructure and Properties of Cr3C2-Rich Binary Cr3C2-WC-Ni(Co) Hardmetal Coatings

Hardmetal coating compositions containing both WC and Cr3C2 are less intensively studied than WC-Co(Cr) and Cr3C2-NiCr. In particular, compositions with Cr3C2 as the main phase are relatively new in the market. In this contribution, two commercial agglomerated and sintered feedstock powders with similar compositions (42Cr3C2-42WC-16Ni and 45Cr3C2- 37WC-18NiCoCr) were studied. Both powders differ in their porosity and the melting behavior, as was found by DSC experiments. Coatings were deposited with a liquid-fueled HVOF process (JP 5220). Optimization of the spray conditions was evaluated with five different spray parameter sets. Coating microstructures and phase compositions, as well as microhardness HV0.3 and abrasion wear resistance were less influenced by the spray parameter sets. At the same time, significant differences in deposition efficiency between the two compositions were observed, which might be related to the differences in the melting behavior of the compositions and the powder porosity. However, coating microhardness and abrasion wear resistance were similar for each of the spray parameter sets. Coating microstructure and phase composition were studied with a focus on the interaction between Cr3C2 and WC and will be discussed in detail.