Comparison Of Wc-10Co-4Cr Coatings Properties Produced By Hvof And Hvolf Processes For Application In Petrochemical Industry

This research work presents the results of a comparative study conducted to compare the coatings properties of WC-10Co-4Cr coats produced by two different Oxy-fuel coating process; high velocity oxy-gas fuel (HVOF) and high velocity oxy-liquid fuel (HVOLF) thermal spraying techniques. The coats were deposited directly on low carbon steel substrate without bonding coats. Scanning electron microscopy (SEM) was performed to study microstructural analysis and to quantify the porosity and cross-sectional coat thickness. Furthermore, the mechanical properties of both coating processes were defined in terms of bond strength and micro hardness. The results show that the liquid fuel sprayed coatings (HVOLF) produced higher adhesion strength coats (~ 73 MPa) compared to (~ 68 MPa) for HVOF. Similar results observed for micro-hardness of 1255 VHN and 1032 VHN, respectively. The surface roughness and porosity were less for HVOLF 4.32μm/0.85% compared to HVOF results of 5.26μm/1.29% porosity. This superior result in coats properties of HVOLF compared to HVOF was attributed due to less decarburization in HVOLF and hence less production of hard secondary phases of W2C.