Tungsten Carbide Deposition Processes for Hard Chrome Alternative: Preliminary Study of HVAF vs. HVOF Thermal Spray Processes
C. Lyphout, University West, Production Technology West; J. Kitamura, K. Sato, J. Yamada, Fujimi Incorporated; S. Dizdar, Höganäs Sweden AB
The Electrolytic Hard Chrome (EHC) method, which is still widely utilized in the printing, automotive, and off-shore industries, is coming to be subjected to strong restrictions in the next decade in the use of hexavalent Chromium, with the increasing strengthening of European normative. Alternative methods to EHC, such as High Kinetic Thermal Spray Technology, have shown a growing interest the past decades.
Compared to conventional HVOF processes which pioneered the development of WC-based coated materials, newly developed HVAF systems are processing at higher kinetic energy and more particularly at lower temperature, which significantly reduces feedstock oxidation and decarburization, then increasing respective wear and corrosion resistance properties. A preliminary investigation of HVOF- and HVAF-sprayed coatings is here proposed on the evaluation basis of material decarburization, coating porosity and microhardness. Role of carbides size and morphology on coating adhesion strength, wear and corrosion resistance properties are preliminary discussed.
