Analyzing the impact of High-Velocity Oxy-Fuel (HVOF) Spray Parameters on the Corrosion Performance of WC-12Co Coatings Using a Taguchi Design

چکیده مقاله

The High Velocity Oxy-Fuel (HVOF) process is a leading method for depositing dense, adherent cermet coatings, of which WC-Co is the most common. Since the corrosion performance of HVOF-sprayed cermets is governed by microstructure—including porosity, cracking, and interfacial properties—this research aims to systematically investigate the impact of key HVOF spraying parameters on the corrosion resistance of WC-12Co coatings. An L9 orthogonal array based on the Taguchi method was employed to investigate the effects of four process parameters: spray distance, oxygen-to-fuel ratio, gun speed, and powder feed rate. The powder morphology and coating microstructure were characterized using scanning electron microscopy (SEM), while phase composition and the extent of tungsten carbide decomposition in the coating were analyzed via X-ray diffraction (XRD). The results revealed that the spraying interval was the most critical parameter, directly influencing both porosity and the formation of amorphous-nanocrystalline phases from WC decomposition. Between these two competing factors—porosity (detrimental to corrosion resistance) and amorphous-nanocrystalline phases (beneficial)—the latter was dominant. The combined application of the Taguchi method and grey relational analysis identified the optimal parameter set for concurrently improving peak intensity, porosity, and corrosion current as a spray distance of 200 mm, an oxygen/fuel ratio of 3.5, a powder feed rate of 58 g/min, and a gun speed of 1 mm/s.