Solid Particle Erosion Characteristics of HVOF Cermet Coating and Multiple-carbide Hardface Overlay

HVOF thermal spray coatings and hardfacings find extensive applications in thermal electric power generation plants for the protection of vital boiler parts. Hardfacing electrodes containing multiple-carbides offer excellent wear properties. The research work presents the solid particle erosion behaviour of WC-10Co-4Cr alloy powder when deposited with HVOF thermal spray coating technique and that deposited along with the multiple carbides containing hardfacing electrode. Coating and hardfacing were formulated on SS 310, a material commonly used for the fabrication of pulverized coal burner nozzle (PCBN). Erosion testing was carried out in air-jet erosion tester simulating the conditions prevailing in the PCBN.  The coating couldn’t sustain in 1 hour erosion testing, leaving the substrate exposed to the erodent attacks. To know the probable mode of metal loss, surface morphologies of the eroded specimens were studied through BSEI. Hardfacings and coatings were characterized with optical microscopy, SEM-EDS analysis, XRD analysis and micro-hardness testing.