Novel liquid fuel HVOF torches fueled with ethanol: relationships between in-flight particle characteristics and properties of WC-10Co-4Cr coatings

Commercial WC-10Co-4Cr powder was sprayed by a novel HVOF process with ethanol used as fuel. Ethanol benefits from environmentally friendly features and less consumption of oxygen compared to conventional fossil liquid fuels (i.e. kerosene). Investigations were carried out to determine the influence of different oxygen/fuel ratios on the evolution of the velocity and temperature of in-flight particles in correlation with the properties of the resulting WC-CoCr coatings. The phase compositions, microstructures, porosity data, microhardness and fracture toughness were tested for comparation. The velocity and temperature of particles strongly depend on the total flow rate of oxygen and fuel. The variation of the ethanol flow rate has a more obvious influence on the velocity and temperature of the particles than that of oxygen. Detailed correlation of particle parameters and the coating properties are elaborated in order to deduce particle parameter ranges providing the coatings exhibiting optimum properties.