Optimization of WC-based HVAF-sprayed Coatings for Alternative to Hard Chromium: Role of Carbides Grain Size and Mean Free Path on Coating Wear and Corrosion Properties

摘要

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 process. Lower thermal energy and higher kinetic energy of sprayed particles achieved by newly developed HVAF systems, significantly reduces decarburization, and increases wear and corrosion resistance properties, making HVAF coatings attractive both economically and environmentally. Two different agglomerated and sintered powder chemistries, respectively WC-Co and WC-Co-Cr, have been deposited by the HVAF-M3 process, and evaluated on the basis of material decarburization, coating porosity and microhardness. The role of carbides grain size, carbides contiguity and binder mean free path on coating microstructure, wear and corrosion resistance properties are emphasized and discussed as potential optimization of coating for high wear and corrosion performances.