Researchers from Kermetico Inc., Benicia, Calif., and H.C. Starck, Germany, discussed the latest developments in HVAF Flash Carbide as Economical Alternative to Electroplated Hard Chrome at the ITSC 2018 conference in May.
Applications of thermal spray coatings for replacement of electroplated hard chrome are limited due to the high cost of today’s thermal spray coatings. This cost is associated with the need to spray relatively thick layers followed by grinding to specified dimensions. A substantial part of the applied coating is removed during grinding.
However, the developed technology for the HVAF “Flash Carbide” process deposits very fine powders of WC-10Co-4Cr, creating dense layers at a thickness as low as 25 to 40 microns, and with surface roughness Ra 1.5 to 1.6 microns. Such thickness is comparable with the common tolerances on rods and shafts, while the as-sprayed coating roughness is similar to that of a typical ground surface. As a result, the dimensional grinding is not needed.
Subsequent polishing removes only 5 to 9 microns, to reach Ra 0.1 to 0.2 microns – sufficient for the majority of industrial applications using electroplated hard chrome. Superior properties and low cost of the HVAF “Flash Carbide” makes it an attractive economical alternative to EHC.
Dr. Andrew A. Verstak , Kermetico Inc., Benicia, California
Dr. Benno Gries , H.C. Starck STC GmbH, Goslar, Germany
