Tribological properties of the two-step thermally deposited chromium films

Chromium thin films were prepared on glass substrate via a two-step thermal deposition and their structural, chemical and tribological properties were determined. The X-ray diffraction pattern of the two-step thermally deposited chromium film showed the presence of well-defined body-centered cubic Cr metal structure with a prominent (1 1 0) plane. X-ray photoelectron spectroscopy depth profile showed a presence of ∼2% of oxygen in the film within the first five etching cycles showing oxygen incorporation. Dry sliding wear experiments at temperatures ranging from 20 to 200 °C were conducted. The thin films were worn with either 100Cr6 or 440C bearing balls using a ball-on-disk sliding configuration at a contact load of 1 N. Friction coefficient and coating wear rates were measured and wear tracks were analyzed using optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thin films exhibited low wear rates at room temperature and an unexpected wear behavior at the elevated temperatures. Only the first half of the metallic chromium film was worn out after ∼18 m of dry sliding at room temperature, whereas increase in temperature resulted in a decrease in wear resistance of the film.