Unique synergistic effects of ternary multi-dimensional CNT/g-C3N4/MoS2 hybrid as a paraffin oil additive for improved tribological properties

Graphitic carbon nitride (g-C3N4) nanomaterials have drawn much interest in the lubrication and friction fields owing to their excellent self-lubrication and mechanical performances. However, the easy agglomeration and poor dispersion stability of single g-C3N4(CN) have always been a headache. In the work, multi-dimensional ternary carbon nanotube, graphite carbon nitride, and molybdenum disulfide (CNT, CN, and MoS2) hybrids were fabricated by hydrothermal method. The microstructure and its reinforcement impact on the tribological properties of the corresponding paraffin oil were systematically studied. The results showed that the zero-dimensional spherical MoS2, one-dimensional tubular CNT, and two-dimensional lamellar CN are uniformly compounded. The tribological test results display that average friction coefficient and wear rate of the 0.2 wt% CNT/CN/MoS2 are decreased by 39.23% and 91.97% lower than those of pure paraffin oil, CNT and CN/MoS2 with the same concentration, respectively. The significantly improved tribological properties of lubricating oil is ascribed to even dispersion of CNT, CN, MoS2 in CNT/CN/MoS2 hybrids, self-lubricating effect of MoS2 and CN, and load-bearing ability of CNT and CN nanosheets, and also the generation of lubricating film between friction pairs during the wear process.