Optimized mechanical and tribological properties of thermally sprayed ceramic coatings by constructing crystalline–amorphous heterojunctions

Abstract

Self-lubricating ceramic coatings are limited in their practical applications by weak interfacial bonding between lubricants and ceramics, as well as degradation of mechanical properties caused by tribological design. Herein, we fabricated a robust self-lubricating ceramic coating by combining in-situ synthesis of carbon and thermal spray technology process. Results show that carbon grows in situ in the pores, microcracks, and grain boundaries of thermally sprayed YSZ coatings. Benefiting from the YSZ/carbon heterojunctions and increasing densification, the composite coating exhibits superior mechanical properties. Furthermore, owing to the formation of a well-covered robust lubricating film at the frictional interface, the coefficient of friction can be reduced by 77.1 % to 0.22, and the specific wear rate drops from 6.33 × 10-4 mm3 N−1·m−1 to 2.25 × 10-7 mm3 N−1·m−1. The proposed strategy eliminates the biggest pain points of mechanical properties degradation of traditional ceramic self-lubricating coatings caused by tribological design and is believed to have great potential applications in wide engineering sectors.