Peilong Li

Tribological Behaviors of Polyurethane Composite Coatings Filled with Ionic Liquid Core/Silica Gel Shell Microcapsules

Silica gel shell microcapsules containing ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) have been successfully synthesized through an interfacial self-assembly process and solgel reaction. They are further developed as filler to improve the tribological property of polyurethane composite coatings. The tribological behaviors of the polyurethane composite coatings filled with microcapsules have been systematically investigated using ball-on-disk tribological test. The results showed that the polyurethane composite coating filled with microcapsules displayed much lower friction coefficient and wear, compared with that of unfilled one. It is demonstrated that the ionic liquid released from the broken microcapsules during the friction process lubricates the rubbing surfaces and prevents a direct contact between steel ball and coating, leading to a lower friction coefficient and a lower wear width and depth.

Fabrication of CdS∕Si nanocable heterostructures by one-step thermal evaporation

Coaxial CdS∕Si nanocable heterostructures with a length of hundreds of micrometers and an average diameter of 100nm were fabricated via one-step thermal evaporation of CdS powder under experimentally controlled conditions. The CdS cores have a hexagonal crystal structure. The Si sheaths are amorphous and can be directly grown on the CdS surfaces from the silicon substrate via a vapor-liquid-solid mechanism without an extra Si source. The photoluminescence of the nanocables presents two emission bands, around 510 and 590nm. This simple method may be applied to other Si-sheathed heterostructures, which can be used in nanodevices with various functions.

Graphene Oxide-Grafted Hybrid-Fabric Composites with Simultaneously Improved Mechanical and Tribological Properties

Poor fabric/matrix interfacial adhesion and inferior thermal properties of polymer matrix severely hinder the continued development of hybrid Nomex/PTFE fabric-reinforced polymer composites for advanced tribological applications. Graphene oxide (GO) grafted on fibers has been widely used to reinforce polymer composites and improves the fiber/matrix interface. This study focuses on the tribological and adhesion properties of GO-grafted hybrid-fabric composites. Hybrid Nomex/PTFE fabric-GO multiscale reinforcement was prepared by a novel technique where a hydrothermal carbonization functional primer coating was initially applied on hybrid-fabric followed by chemically attaching GO. The microstructure and chemical composition of modified hybrid-fabrics were comprehensively investigated by SEM, FTIR, and XPS. Results indicated an obvious increase in surface functional groups and wettability. Tensile and peeling testing results showed that the GO-grafted hybrid-fabric composites exhibited 27.3 and 73.6% enhancement in tensile and interfacial bonding strength, compared to that of pristine hybrid-fabric composites. Furthermore, GO modification forming a percolating network on hybrid-fabric within the polymer matrix effectively promoted the thermal stability and heat conductivity of hybrid-fabric composites. Wear tests also showed the anti-wear performance of the modified hybrid-fabric composites was enhanced obviously due to improved interfacial bonding and thermal properties.