Processing-structure-property correlation and decarburization phenomenon in detonation sprayed WC-12Co coatings

Abstract

In this paper, we demonstrate how the microstructure evolution in terms of nature/extent of decomposition of WC as well as properties of WC-12wt.% Co coatings is critically dependent on variation of oxygen-fuel (OF) ratio. The coating deposition was carried out over a wide range of OF ratios using a detonation spray technique, and particle velocity was measured using a high-speed particle diagnostics system. The presence of free W and increased W₂C phase is observed under deposition at higher OF ratios of 1.5 or 2.0, and this has been confirmed using XRD, EBSD and SEM-EDS elemental mapping. In order to obtain representative hardness and modulus of the as-deposited coatings, careful measurements and analysis of indentation response (cross-section and surface) were carried out using nanoindentation and Vickers hardness testers. Based on our experimental results, a major emphasis has been put forward to establish a processing-structure-property correlation for detonation sprayed WC-12Co coatings.