中国科学院材料磨损与防护重点实验室/先进润滑与防护材料研究发展中心知识库

Fluorine-containing amorphous carbon films [fluoring-containing diamond-like carbon (F-DLC)] were fabricated on Si wafer by direct current plasma enhanced chemical vapor deposition (dc-PECVD) technique using CF₄ and Ar as gas sources, confirmed by XPS and Raman analyses. The friction tests were carried out on a rotating ball-on-disk apparatus in high vacuum atmosphere (≤5.0 × 10⁻⁴ Pa) at the load of 0.5 N selecting glass (mainly containing silicon–oxygen tetrahedron structure) and Al₂O₃ with the same hardness and surface roughness as the counterpart balls. The results indicate that glass/F-DLC results in lower friction coefficient of 0.14 than that of the Al₂O₃/F-DLC (0.20). At the same time, no wear was occurred, and the transfer layer was not formed on the counterpart ball for glass/F-DLC, while the wear of Al₂O₃/F-DLC is slightly larger than that of glass/F-DLC. However, just like the glass ball, there is no formation of transfer layer on the Al₂O₃ ball surface. Furthermore, the chemical state of fluorine in the film after friction, which mainly existed in the form of the C–CF and C–F bonds, did not change compared with the F-DLC film, while the fluorine content has changed significantly. As a result, it is assumed that interface electrostatic interaction based on acid–base theory plays an extremely important role in the process of friction.