Erosion wear performance of HVOF and cold spray coatings deposited on T-91 boiler steel

Abstract

Erosion wear in boiler tubes in coal based boilers is one of the serious problem and often results in downtime. After studying the literature, it was observed that thermal spray coatings are one of the effective solutions in reducing the erosion wear of boiler tubes. In this research work, the comparative erosion wear study of uncoated, HVOF coated and Cold spray coated samples of T-91 steel in simulated coal fired boiler conditions were performed. The Ni powder coatings were deposited on the substrate and impacted at 30°, 60° and 90° impingement angles with alumina erodent employing an air jet erosion tester. The erosive wear with respect to weight loss was maximum at 30° impingement angle, that was reduced at an impingement angle 60° and minimum at an impingement angle of 90°. This is erosive wear behavior of ductile materials. The erodent discharge rate was fixed at 2 g/min and air temperature at 800 °C. The cold spray coatings can reduce the weight loss from 40 to 60%.