Internal Diameter Coating by Warm Spraying of Fine WC-12Co Powders (? 10 + 2 µm) with Very Short Spray Distances up to 10 mm

Abstract The internal diameter (ID) coating by means of thermal spraying is currently experiencing growing interest in science and industry. In contrast to the well-established plasma- arc-based spray techniques, there a lack knowledge concerning kinetic processes such as HVOF, HVAF warm (WS). A major challenge represents necessity short distances compact design novel ID guns with reduced combustion power. Conventional WC-Co powders (? 45 + 15 µm) are not able achieve sufficient heat momentum transfer. use fine < µm offers an approach overcome this drawback they feature larger surface-to-volume ratio lower mass. However, processing requires suitable equipment sensitive parameter adjustment. study, WC-12Co 10 2 gun (HVOF N ) “ID RED” (Thermico Engineering GmbH, Germany) was investigated. First, flame profile well in-flight behavior particles along jet (spray SD = 10-80 mm) analyzed at different nitrogen flows NF 15-115 L/min find intervals. Subsequently, planar steel samples were coated 10-50 mm constant 90 L/min. Analyses regarding microstructure, mechanical properties phase evolution coatings performed. aim study scrutinize shortest feasible distances. Finally, tubes (internal 81.6 wall thickness 10.0 20 investigate how far results can be transferred parts. Correlations between particle behavior, microstructure made.