Coatings are normally employed to meet some functional requirements. There is a kind\nof self-generated coating during use, such as the transfer layer during sliding, which may greatly\naffect the tribological behavior. Although the transfer layer has aroused much attention recently,\nthe formation of the transfer layer closely depends on the service conditions, which need to be\nfurther studied. In this paper, the effects of sliding speed, normal load, and duration of wear test\non the transfer layer thickness during friction of Ni/PTFE (Polytetrafluoroethylene) composites\nwere experimentally investigated. The formation mechanism of transfer layer and the relationships\nbetween tribological properties and transfer layer thickness were analyzed in detail. It was found\nthat the transfer layer thickness increased with increases of sliding speed and normal load; and after\na period of wear test, the transfer layer thickness remained stable. The transfer layer thickness\ncorrelates linearly with the friction coefficient and wear volume of the PTFE composites. With the\nincrease of the transfer layer thickness, the friction coefficient decreased, while the wear volume\nincreased, which means that a uniform, thin, and stable transfer layer is beneficial for the reduction\nof friction and wear of the polymeric composites.
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