Laser Surface Treatment of Nickel‐Alumina Coating for Enhancement of Erosion and Corrosion Resistance of High Speed Steel Vanes

ABSTRACT

The sliding wear between hydraulic vane tip and the inner surface of the cam ring can cause fatigue cracks and affect the durability of the vane surfaces. This paper examines the effect of laser surface treatment on plasma sprayed nickel −10% alumina coating on erosion and corrosion resistance of high speed steel (HSS) vanes. The hydraulic vanes were subjected to surface treatment using 20 W nanosecond laser at varying laser power of 6 W, 13 W, and 18 W. Erosion test was performed using custom built slurry erosion test rig running with ISO‐32 grade hydraulic oil mixed with 5% quartz. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were performed to evaluate the corrosion behaviour. The results showed that laser surface treatment had improved the surface texture and micro hardness of the coated vanes. The highest corrosion inhibition efficiency of 81.3% was observed for the coated vane treated at the highest laser power. This trend was consistent in the EIS investigation, with inhibition efficiency reaching 78.5% for the coated vane treated at the highest laser power and 65% for the untreated coated vane. Scanning electron microscope depicted uniform dense coating with some pores, splats and unmixed powders.