Exploring Synergistic and Antagonistic Interactions of MoS2 and Multi-Wall Carbon Nanotube additives in a Composite Top-of-Rail Friction Modificator

The effects of MoS2 and Multi-Wall Carbon Nanotube (MWCNT) additives onto thermal, mechanical and tribological properties of the vinyl ester polymer-matrix composites were systematically studied. Monocomponent and mixed additive compositions with concentrations ranged between 0 and 3 wt. % showed complex behaviours. Under oxidative environment, MoS2 suppressed high-temperature matrix decomposition process at 513 ºC, while MWCNTs suppressed the matrix decomposition process at 524 ºC. The samples with low MWCNT/MoS2 ratios showed two distinct glass transitions, while the samples with high MWCNT/MoS2 ratios presented a single transition around 100-120 °C. Tribological behaviour of steel-steel roiling-sliding simulating wheel-rail contact in presence of the composites significantly varied depending on the additives’ composition. The mixed-component composites yielded coefficient of traction close to the desired range 0.25-0.35. Wear of the “wheel” disk was mainly controlled by the composite capacity to form secondary transfer film by aggregation and compaction of wear debris. Wear of the “rail” disk likely depended on the capacity of the transfer layer on the “wheel” disk to release MoS2 and transfer it onto the “rail” disk.