Abstract
This work proposes a methodology to monitor the wear of tribological coatings by introducing a sensing layer between the coatings and substrate. The sensing mechanism is based on luminescence from the sensing layer when the coatings are worn out. In this work, the wear sensing layer consisting of as-purchased luminescence ZnS:Cu powder with particle size of 10-20 micrometers and epoxy resin (EP/ZnS:Cu) is initially fabricated. The as-prepared EP/ZnS:Cu coatings are subsequently coated with amorphous carbon (a-C) films by two deposition methods, i.e. sublimation of fullerene (C60) in electron beam excited plasma (EBEP) and pulsed vacuum arc deposition (VAD) methods. As-prepared EP/ZnS:Cu coatings show a green luminescence spectrum at the peak centre of 525 nm under irradiating with a UV light at 365 nm. After being coated with a-C films and irradiated with a UV light, the luminescence is undetected through a-C films. The performance of the coatings is investigated by a ball-on-disk friction test. It is found that after the a-C film is removed or worn out, the luminescence from the sensing layer is redetected. These results suggest the feasibility of wear monitoring of a-C film through the luminescent layer.
