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The tribological behaviour of unfilled thermoplastic polyurethane (TPU) and a polymer sphere filled (TPUG) thermoplastic polyurethane have been studied under oscillating sliding condition against cast iron as a counterpart. In the case of unfilled TPU, the wear mechanisms are dominated by particle detachment and roll formation. In principle, TPUG also showed a similar wear mechanism as that of unfilled TPU; in addition, particle pull-out and delamination are also observed. Wear volume of TPUG was significantly higher than that for the unfilled TPU and this is attributed to the different material removal processes taking place in the material during sliding. The polymer spheres as a filler material deteriorated the wear resistance of TPU because of improper adhesion and bonding of filler in the TPU matrix and therefore it contributed to more wear. In case of TPU the friction behaviour was strongly dependant on the temperature and surface roughness of the counter body. The results showed that below the glass transition temperature higher friction values are observed with higher counter body surface roughness. However, above the glass transition temperature, higher friction values are observed with a smoother surface roughness of the counter body. In case of TPUG, the friction behaviour was not significantly dependent on surface roughness of the counter body.
The influence of temperature and counterbody material on the tribological properties of a-C:H
coatings deposited on Cronidur 30 steel has been investigated in a lubricated ball on disk
contact situation with alpha-alumina and silicon nitride as counterbodies. The results show, that the wear volumes of the systems increase exponentially with increasing temperature, for alpha-alumina more than for silicon nitride. Two different wear mechanisms seem to have a
major influence: First, the abrasive action due to materials hardness and second, the tribo-oxidation when silicon nitride is counter material.
The friction and wear properties of polyetherimide composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120 °C) was investigated. The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. In case of carbon fiber composite abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated.
The influence of temperature and counterbody material on the tribological properties of a-C:H coatings deposited on Cronidur 30 steel has been investigated in a lubricated ball on disk contact situation. The results show, that the wear volumes of the system increase exponentially with increasing temperature. Two different wear mechanisms seem to have a major influence: First, the abrasive action due to materials hardness and second, the tribooxidation when silicon nitride is counter material.