Erosion Behavior of WC-10Co-4Cr HVOF Coatings

Abstract

Abstract Among the WC based cermets coating materials, those using the 10%Co-4%Cr matrix demonstrate excellent wear and corrosion properties. In this paper the erosion behaviors of WC-10%Co-4%Cr HVOF coatings was evaluated under different erosion conditions. The coatings were obtained from the JP-5000 gun using kerosene as fuel and the Diamond Jet gun using propylene and hydrogen. Two types of powder morphology were used: the first type was coarse and angular while the second was smaller, porous and spherical. The coatings were submitted to dry and slurry erosion. Erosion tests were performed at room temperature for both dry and slurry erosion. Dry erosion was evaluated by jet erosion while for slurry erosion, two different tests were performed: Coriolis and jet impingement erosion. Experimental results show that for the same powder, the erosion resistance measured by the Coriolis test exhibits 100% variation while for jet impingement it varies only by 20% depending on gun and spray conditions. The results also show that the powder selection is one of the key factors controlling the coating performance. The selection of powder can affect the Coriolis erosion resistance by more than 300% and the dry and slurry erosion resistance by 75%. The results are analyzed as a function of the processing and coating microstructure.