Mechanical Properties and Cavitation Erosion Behavior of CeO2-Modified Dual-scale WC-10Co-4Cr Coating Prepared by HVOF

Cavitation erosion is a major failure mode of hydraulic turbine components. Coatings could be an effective solution to this problem. In this study, a CeO2-modified (1 wt%) dual-scale WC-10Co-4Cr powder (WC composed of 70 wt% micrometer WC (2.5 mu m) and 30 wt% nanometer WC (100 similar to 200 nm)) was fabricated by agglomeration and sintering. CeO2-modified dual-scale WC-10Co-4Cr coatings (C-coating), dual-scale WC-10Co-4Cr coatings (D-coating), and micrometer WC-10Co-4Cr coatings (M-coating) were then deposited using a high-velocity oxygen fuel (HVOF). The mechanical properties and cavitation erosion behavior of these coatings were studied. The results showed that the CeO2-modified WC-10Co-4Cr coatings could effectively reduce decarburization in the powder preparation and HVOF process, the coatings having the highest WC retention rate. The C-coatings possessed a higher fracture strength (6.3 MPa m(1/2)) and hardness (1348.2 HV0.3) than the D-coatings by more than 8.6 and 3.0%, respectively. The cavitation erosion resistance of the WC-10Co-4Cr coatings was affected by their microstructure and mechanical properties. The CeO2-modified coatings exhibited improved fracture toughness and hardness, reduced porosity, and, as a result, the C-coatings had the best cavitation erosion resistance.