Tribology and wettability of Na-ion implanted glassy carbon

A study has been made of friction, wear and wettability of ion implanted glass like carbon. Substrates used were glassy carbon (GC). Na-ions of 150 keV were implanted in GC with doses ranging from 1×10¹⁵ to 1×10¹⁷ ions/cm² at room temperature. Tribological tests were carried out using a ball (SUJ-2 or alumina) on disk (GC) equipment. Contact angles of water were measured by means of a sessile drop method. It is found that friction coefficients during wear tests were around 0.2 and unstable for the non-implanted specimen, and stable for implanted specimens. The lowest friction coefficient was 0.05, observed for the system of an alumina ball on the higher dose specimen. Wear resistance was improved with the dose over 1×10¹⁶ ions/cm². The contact angle of water was about 87 degrees at the dose up to 5×10¹⁶ ions/cm², and it decreased to 43 degrees at the dose of 1×10¹⁷ ions/cm². It is considered that the improvement of wear resistance is caused by the generation of diamond like carbon structure by radiation effect and the reduction of the contact angle is influenced by implanted Na. It is concluded that Na-ion implantation in GC results in high wear resistance and different wettability