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In this study, epoxy resin (EP) composites were prepared by using molybdenum disulfide (MoS2) and helical carbon nanotubes (H-CNTs) as the antifriction and reinforcing phases, respectively. The effects of MoS2 and H-CNTs on the friction coefficient, wear amount, hardness, and elastic modulus of the composites were investigated. The tribological properties of the composites were tested using the UMT-3MT friction testing machine, non-contact three-dimensional surface profilometers, and nanoindenters. The analytical results showed that the friction coefficient of the composites initially decreased and then increased with the increase in the MoS2 content. The friction coefficient was the smallest when the MoS2 content in the EP was 6%, and the wear amount increased gradually. With the increasing content of H-CNTs, the friction coefficient of the composite material did not change significantly, although the wear amount decreased gradually. When the MoS2 and H-CNTs contents were 6% and 4%, respectively, the composite exhibited the minimum friction coefficient and a small amount of wear. Moreover, the addition of H-CNTs significantly enhanced the hardness and elastic modulus of the composites, which could be applied as materials in high-temperature and high-pressure environments where lubricants and greases do not work. [ABSTRACT FROM AUTHOR]

The main focus of current research in polymeric matrix brake composites is on searching out a replacement for copper, which has been recently proved to be a hazard to human health and the environment. In this paper, rare earth lanthanum oxide was explored for the replacement of copper in composites. The mechanism of the role of lanthanum oxide in brake composites to replace copper was analyzed. Four series of polymeric matrix brake composites with various amounts of copper (15, 10, 5 and 0 wt %) and rare earth lanthanum oxide (0, 5, 10 and 15 wt %) were developed, in which the copper was gradually replaced by lanthanum oxide in the formula. These series were characterized in terms of physical, thermo-physical and mechanical properties. The results show that lanthanum oxide can be successfully used as a replacement for copper in brake composites. Brake composites with 15 wt % lanthanum oxide that are copper-free are considered optimal, where tribo-properties are considered best. Compared with the addition of copper in brake composites, lanthanum oxide is more conducive to the formation of compacted friction films and transfer films, which is beneficial to the tribological properties of the brake composites. The addition of La2O3 to the brake composites can cause the reaction between La2O3 and Al2O3 to form LaAlO3, and the reaction between Al2O3 and BaSO4 can produce Ba18Al12O36 and Al2SO4 during the friction and wear processes, which can effectively improve the tribological properties of the brake composites at elevated temperature. This research was contributive to the copper-free, metal-free and eco-friendly brake composites. [ABSTRACT FROM AUTHOR]