Microstructure and wear resistance of WC-Co by three consolidation processing techniques

Tungsten carbide-cobalt (WC-Co) has been extensively employed as an abrasion/wear protective material. However, carbon loss (decarburization) of WC-Co powders during processing reduces the efficiency of the material against abrasive wear. This paper examines the efficiency of three consolidation processing techniques to obtain coatings and bulk samples from WC-Co powder. In this work, high velocity oxy-fuel (HVOF) spray forming and laser engineered net shaping (LENS®) were applied to make WC-Co coatings; spark plasma sintering (SPS) was used to produce bulk WC-Co samples for comparison. The microstructures of two types of coatings and one bulk sample were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) to recognize material modification. In addition, porosity and tribological properties of the WC-Co samples were tested. The ultra-microindentation technique was applied to measure the universal hardness and the elasto-plastic properties of the samples. Experiments using a tribometer (ball on disc configuration) under dry conditions have been performed in order to evaluate the friction and wear properties of the different systems.