Microstructural Characteristics of Arc Sprayed CoCr-based Coatings

Due to their superior wear resistance and oxidation behaviour, Stellite™ coatings are widely used in industrial applications, where the material is exposed to high temperature. Common processes for applying Stellite™ coatings include the high velocity oxy-fuel spraying, laser cladding, and plasma transferred arc welding. Although Stellite™ welding consumables or similar welding consumables in the form of cored wires (on CoCr basis; without industrial property rights) are commercially available, there are hardly any studies on arc sprayed Stellite™ coatings available in the literature.

In this study, the microstructural characteristics of an arc sprayed deposit were investigated, which was produced using a CoCr based cored wire which additionally contains 4.5 wt.% of tungsten. The produced deposit was examined in its as-sprayed state as well as after different heat treatment procedures. For various states, the microstructure formation was scrutinized by means of electron microscopy and energy dispersive X-ray (EDX) spectroscopy. Phase transformation processes were determined by means of X-ray diffraction (XRD) analyses using synchrotron radiation. Hardness tests including hot-hardness measurements were conducted and correlated to phase transformation processes. Thus, strengthening effects such as solid solution hardening and precipitation hardening were identified and discussed to findings of conventional route of manufacturing.