Characterization of thermal sprayed stellite 6 coatings

This paper studies the microstructure and properties of stellite6 coatings produced by high velocity oxy-fuel (HVOF) presses on low carbon steel (St 37). The microstructure، porosity، coating thickness، phase formation and microhardness of the coating were investigated using the combined techniques of optical microscopy، X-ray diffraction (XRD) and scanning electron microscopy/ energy dispersive spectrometry (SEM/EDS). The coatings exhibited a layered microstructure due to deposition and re-solidification of molten powder particles. Porosity، unmelted and semi melted particles and inclusions were present in the microstructure of the coating. In addition، the coating showed porosity content of about 2% and a hardness of about 700 HV. The thickness of as-sprayed coatings was about 500 m. The adhesive strength of coating to substrate was more than 67 MPa. The result of XRD indicated that no phase transitions occur in feedstock powder after HVOF spraying and the coatings consist of a Co-rich matrix of face centered cubic (FCC).