EROSION BEHAVIOUR OF STELLITE COATED STEEL COMPONENTS

Abstract

Stellite coatings on stainless steel have been provided using high velocity oxy-fuel (HVOF) thermal spray process with assistance from Bharat Heavy Electric Limited (BHEL), Haridwar and Central Scientific Organization Chandigarh. The satellite coatings significantly enhance the erosion resistance of the base material. The erosion behaviour of the coatings, base metal and at the base/coating interface has been investigated by using erosion testing rig containing sand and water mixture. The erosion tests have been conducted to determine the erosion rate of coated and base material specimen. It is seen that although initial weight loss is not much different from that in the base material, the weight loss decreases in stellite coated specimens with increase in erosion time. Extensive study has been conducted using optical microscopy and scanning electron microscope (SEM). The photographs of microstructure of coated and base have been taken to study change in microstructural properties of the coated specimen. The SEM photographs were taken to study the eroded surface topography of the coated and base material. The erosion mechanism involves dislodging of material particles as well cutting and ploughing of target surfaces by hard silt particles.