High-temperature tribological performance of the Si-gradually doped diamond-like carbon film

Silicon containing diamond-like carbon films is of value for engineering applications operating at the temperature above 200 degrees C. This work presents a Si-gradually doped diamond-like carbon film with increasing the Si content from outer layer to inner layer deposited by plasma-assisted reactive magnetron sputtering process. The microstructure, chemical bonding state and temperature-dependence tribological properties upto 500 degrees C of the film are investigated by using focused ion beam/transmission electron microscope (FIB/TEM), X-ray photoelectron spectroscopy (XPS) techniques and ball-on-disk tribometer, respectively. The results show that the asdeposited Si-gradually doped DLC film exhibit amorphous structure. The wear track tested at 500 degrees C are composed of carbon, SiO2 and silicon oxide. High-temperature tribological tests show that the friction coefficient values are 0.05 +/- 0.01, 0.02 +/- 0.004 and 0.09 +/- 0.04, while the wear rates are 1.17 x 10-7 mm3/N center dot m, 1.65 x 10- 7 mm3/N center dot m and 1.4 x 10-6 mm3/N center dot m at 300 degrees C, 400 degrees C and 500 degrees C, respectively. It is proposed that the improved high-temperature tribological properties of the Si-gradually doped DLC film benefit from its special composition structure that the inner layer with high Si content provides the required mechanical properties and the outer layer with low Si content reduces the friction coefficient as well as the wear rate.

Automated summary

The study synthesized a silicon-gradually-doped diamond-like carbon film and analyzed its properties using various techniques. It was found that the film exhibited good high-temperature tribological properties, with the high silicon content in the inner layer providing mechanical properties and the low silicon content in the outer layer reducing friction coefficient and wear rate.