Solid Particle Erosion Behavior of WC Coating Obtained by Electrospark Technique and Detonation Spraying

摘要

Solid particle erosion is an important material degradation process. One way of improving the erosion resistance of a material is to suitably modify the surface. Electrospark deposition (ESD) is a well-known surface modification process. Operational simplicity, low capital cost, and low operational cost of the ESD process have made it attractive for high-technology areas in engineering industries. Tungsten carbide (WC) is considered a potential hard material for erosion-resistant application. This material can be deposited by ESD. The present investigation has been undertaken to evaluate the room-temperature erosion response of WC coating deposited by ESD and to compare the erosion behavior of this coating with that of detonation-sprayed WC-Co coating. WC coatings were deposited on mild steel (MS) and aluminum substrate by ESD. Similarly, WC-12% Co coatings were deposited on MS and Al by detonation spraying. The microstructural features and mechanical properties of these coatings were characterized using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction, andmicrohardness testing. The solid particle erosion rate was determined using an erosion test rig. The morphology of the eroded surfaces and the areas beneath the eroded surfaces were examined by means of SEM. The results showed that the WC coating by ESD improves erosion resistance. Although most coatings exhibit a ductile erosion response, WC coating by ESD on Al substrate exhibits a brittle erosion response. Material loss from ESD coating on Al occurs due to the joining of preexisting cracks and the removal of chunk of material.