Industrial Optimization and Efficiency forProcessing of HVOF

Optimising the efficiency of the thermal spray process is critical in industrial environments where high production rates that are linked to excellent quality control must be exploited. In this study, in-flight spray diagnostics have been employed to monitor the spray deposition of WC-10Co-4Cr and Cr3C2-25NiCr feedstocks (Oerlikon Metco AG, Switzerland) using a kerosene fuelled system (GTV HVOF K2, GTV Verschleißschutz GmbH, Germany). Two HVOF barrels, either of straight or conical internal bore, were employed with the goal of controlling the spray footprint geometry as well as maintaining consistent temperature and velocity conditions. The spray plume mapping (DPV2000, Tecnar Automation Ltd., Quebec, Canada) highlights that the conical expansion nozzle allows formation of a spray stream with more favourable deposition dynamics. Additionally the optimum thermal spray stand off distance could be objectively determined, as well as breakup of the composite feedstock monitored.