The study on modulation mechanism for anti-corrosion and low-friction of R0-MoS2 by Ti-/Pb-doped model

Abstract

Based on the first principles, the mechanism of the corrosion and friction failure of 2S-MoS2 (MoS2 stands for R0-MoS2 structure), of the anti-corrosion and friction modulation of Ti-/Pb-doped MoS2 are revealed in the atmosphere environment. For 2S-MoS2, O-doped and H2O-adsorbed 2S-MoS2 interface are formed with interlayer electron reconfiguration, which form the local MoO3 particles and increases their sliding barrier. Although the anti-corrosion role can be shown by trapping interlayer O2/H2O in 2Ti(23)-MoS2 +O2/H2O or by forming a clean Pb-doped interlayer in 2Pb(14)-MoS2 +O2/H2O, the tribological modulation effect occurs only 2Pb(14)-MoS2 +O2/H2O. Compared with 2S-MoS2 +O2/H2O, the tribological performance of 2Pb(14)-MoS2 +O2/H2O is improved by 31.4%/35.2%. These are attributed to 2Pb(14)-MoS2 +O2/H2O with O-passivated structure (S-O/O-S)/H2O-intercalated structure (S/H2O/S) that presents lower shear strength. However, 2Ti(23)-MoS2 +O2/H2O with the cross-linked structure (Ti-O-O-Ti/Ti-OH-Ti) shows higher shear strength. In addition, the ultra-low friction (improved by 26.3%/32.8%, compared with 2S-MoS2 in vacuum) and load-carrying capacity of 2Pb(14)-MoS2 +O2/H2O are also presented and 2Pb(14)-MoS2 +H2O is more excellent (improved by 8.8%, compared with 2Pb(14)-MoS2 +O2). In summary, the tribological modulation of Ti/Pb-doped MoS2 in the atmosphere environment is relative to the structure of their anti-corrosion interface.