A Feasibility Study on Hybrid Use of Thermal Spray Coating and Ultrasonic Nanocrystalline Surface Modification

Abstract

An ultrasonic nanocrystal surface modification (UNSM) technique was applied to the thermally sprayed yttria-stabilized zirconia (YSZ) ceramic thermal barrier coating (TBC) deposited onto a hot tool steel substrate to improve the mechanical and tribological properties. The surface microstructure of the as-sprayed and UNSM-treated coatings was examined using a scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy, while the hardness of the coatings was measured by Vicker`s hardness tester. The friction and wear behavior of the coatings was assessed using a ball-on-disk tribometer against bearing steel (SAE52100) ball at temperatures of 25 °C and 200 °C under dry reciprocating conditions. Results showed that the UNSM-treated coating had smoother surface, lower friction and higher resistance to wear compared to that of the as-sprayed coating. It was found that hybrid use of thermal spray coating (TSC) and UNSM technique is meaningful to bring together synergy effect of two emerging surface technologies.