Screening design of hard metal feedstock powders for supersonic air fuel processing

Replacement of electrolytic hard chromium (EHC) method by Thermal Spray Technology has shown a growing interest the past decades, mainly pioneered by depositing WC-based material by conventional HVOF processes. Lower thermal energy and higher kinetic energy of sprayed particles achieved by newly-developed supersonic air fuel system, so-called HVAF-M3, significantly reduce decarburization, and increase wear and corrosion resistance properties, making HVAF-sprayed coatings attractive both economically and environmentally. In the present work, a first order process map has been intended via a full factorial design of experiments (DoE) to establish relationships between powder feedstock characteristics, such as primary carbides grain size, binder grain size and powder strength, and coating microstructure and mechanical properties. A second order process map was then established to study possible correlations between the deposit microstructural properties and their respective abrasion/erosion wear and corrosion performances.