The dry sliding wear rate of a Fe-based amorphous coating prepared on mild steel by HVOF thermal spraying

Abstract

Wear-resistant amorphous coatings Fe49.7Cr18Mn1.9 Mo7.4W1.6B15.2C3.8Si2.4 of about 300 μm thickness were deposited on mild steel substrate using a high-velocity oxygen fuel (HVOF) thermal spray method. The median Vickers hardness of the as-sprayed coating is 751.9 HV300 g, which further increases by 127% and by 112% when the coating is vacuum heat treated at 650 °C and 800 °C, respectively. The longer the amorphous phase is, the higher the Vickers hardness is. The relatively low porosity indicates excellent wear resistance of these amorphous coating, which were measured using a pin-on-disc method. The wear mechanism of the current Fe-based amorphous coating varies from oxidative wear to delamination wear when the sliding speed changes from low (0.4 cm/s) to high (4.0 cm/s). It is believed that the upsurge in hardness and the wear resistance of the applied coating is due to the optimized selection of the heat treatment process (i.e., at 650 °C), which has a significant impact on the microstructure, as well as the low porosity, with better coating adherence and fewer cracks. Under dry sliding wear circumstances, the coating demonstrated good wear resistance, with wear rates of (2.81–16.30) x 10−6 mm3/N m. Due to the properties, low porosity, and high hardness especially in case vacuum heat treatment 650 °C, these coatings produced by (HVOF) exhibit a high ability to resist better friction and wear performance that indicates to ability application it in facilities steel.

Keywords

• Amorphous
• HVOF
• Ball milling
• Vacuum heat treatment
• Bond coat