Abstract
The surface of any metallic material, is degradating over time from the repeated impact with the microjets and shock waves generated by the bubbles implosion formed during cavitation. Beside the classical methods of heat or thermochemical treatments, several research institutes and hydromechanical equipments users are oriented to the development of metal-ceramic composite coatings deposited by thermal spraying, to provide good protection from corrosive and erosive action of the liquid medium. The researches from this paper analyse the behavior and resistance to erosion cavitation of a Duplex stainless steel whose surface is coated with WC-9Co-5Cr-1Ni powder, deposited by high velocity oxygen fuel (HVOF) spraying method and followed by laser remelting. These investigations, performed in the Cavitation Laboratory of University Politehnica Timisoara, on the vibratory apparatus with standard piezoceramic crystals, outline the need for remelting the sprayed coating in order to improve its adhesion to the substrate and moreover for growing the mechanical impact resistance with the microjets and shock waves developed during cavitation.
Keywords: cavitation; composite; HVOF spraying; laser