Structures and High Temperature Friction and Wear Performances of Ti/Ni-Doped Carbonaceous Mesophases

Abstract

Metallic elements Ti and Ni were doped into the coal tar pitch-derived carbonaceous mesophase (CM) through mechanical alloying in a high-energy ball milling apparatus. The structures for the raw and Ti/Ni-doped carbonaceous mesophases were characterized by X-ray diffractometer. The friction and wear behavior of the Ti/Ni-doped CMs as lubricating additives at different applied loads and temperatures were investigated using a MMU-5G high temperature friction and wear tester. Worn morphologies of the lower 45# carbon steel specimens were observed by scanning electron microscope (SEM). The carbonaceous substances on the worn surfaces were examined by Raman spectroscopic technique. The results have shown that the Ti/Ni-doped CM through mechanical alloying shows an increase in the crystallinity in comparison to that for the raw CM, implying a transition to the more ordered structures caused by the catalytic graphitization at lower temperatures due to the doped Ti/Ni. The Ti/Ni-doped CMs through mechanical alloying, when used as lubricating additives, displayed an obvious high temperature anti-friction and wear resistant effect, and the lager the applied load, the lower the friction coefficient and the wear severity. In addition, as the applied load increases, the carbonaceous substances on the worn surfaces show a rise in the ordered degree, and the corresponding microcrystalline planar size (La) for the carbonaceous substances becomes larger.