Tungsten Carbide-Based HVAF Coatings for Protection of Petrochemical, Oil Drilling and Hydro-Power Equipment Against Wear and Cavitation

Petrochemical, oil drilling and hydro-power equipment operates in conditions of sever wear, corrosion and cavitation. The HVOF sprayed WC-10Co-4Cr coatings are often a choice for protection of the equipment components in these environments due to resistance of the coatings to abrasive wear and erosion. Herewith, the HVOF sprayed WC- coatings exhibit poor resistance to cavitation, caused by their brittleness. Recent developments in HVAF spraying allow the deposition of very WC-10Co-4Cr coatings, 1500 HV300 or higher, using commercial agglomerated-sintered powders. These HVAF coatings do not reveal decomposition of carbides or oxidation, resulting in improved coating ductility and fracture toughness regardless of the high hardness. Compared to the HVOF sprayed counterparts, the HVAF sprayed WC-10Co-4Cr coatings exhibit 30-50% better resistance to abrasive wear and erosion, while cavitation resistance is improved 10-fold. Commercial applications of HVAF sprayed WC-10Co-4Cr coatings are rapidly expanding. The examples are described in this paper.