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Electrostatic cumulative discharges from the surfaces of polyurethane elastomers are often the primary cause of accidents and disasters, such as equipment failures, fires, and explosions, in industries. In this study, in order to improve the electrostatic protection performance of PU as well as to enhance the wear resistance of the PU matrix, copper foam was embedded in polyurethane to form a copper foam-based polyurethane composite with a three-dimensional connected metal skeleton. The mechanical properties, wear resistance, and antistatic capability of the composite were experimentally investigated. The results indicated that the connected metal skeleton structure forms a good conductive network and reduces the static electricity on the polyurethane composite surface to less than 1/10 of that on polyurethane. Moreover, owing to the mechanical support offered by metal skeletons with pore densities greater than 50 pores per inch, the wear resistance of the polyurethane composite is also enhanced, and consequently, its degree of wear is reduced to ∼1/5 of that of polyurethane under the same conditions.

A novel foamed copper/epoxy (FCE) composite possessing improved wear resistance was developed as a rubbing pair material. The composites consist of an open-cell foamed copper skeleton and an epoxy resin and auxiliary additives, such as molybdenum disulfide (MoS2) and multi-walled carbon nanotubes (MWCNTs). A universal UMT-2 friction and wear tester was utilized to study the tribological properties of the FCE composites under dry lubrication conditions. We found that the amount of MoS2, the porosity of the copper foam, and the presence of the MWCNTs all have an effect on the friction and wear properties of the composite materials. The friction coefficient of the composite material gradually decreases as the amount of MoS2 increases; however, the wear rate initially decreases and then increases. When the MoS2 content is 30%, the wear rate reaches a minimum. The wear rate decreases as the porosity of copper foam decreases, but porosity has little effect on the friction coefficient. As the rotation speed of the grinding steel plate and the applied load on samples increase, the wear becomes more significant. The presence of MWCNTs also increases the strength and wear resistance of the epoxy resin matrix. Depth-of-field microscopy and scanning electron microscopy were employed to observe the worn-surface morphologies and wear mechanism. The worn surface of the FCE composite matrix is divided into three parts: the hollow metallic copper skeleton region, the polymer zone, and the transition zone copper skeleton that contains some polymer material. It is important to note that the wear mechanism of the various compositions is adhesive wear and slight abrasive wear, and the fatigue crack that runs perpendicular to the direction of movement begins to form at higher speeds, which results in a higher wear rate.

A novel foamed copper based (FCB) composite is developed as a rubbing pair material. The composites consist of the foamed copper and solid lubricants, such as polytetrafluoroethylene and graphite. Four kinds of FCB composites were fabricated by vacuum filtration, compression moulding, and sintering process in an orderly manner. The thermal and electrical conductivities and tribological properties of the new composites were investigated. Because the interconnected metal skeletons have been embedded in the polymers, the FCB composites possess excellent thermal and electrical conductivities, including nice self-lubricating property. The friction and wear properties were investigated on an M-2000 friction and wear tester. An electric field was imposed between the sample and ring to monitor the tribo-chemical reaction and formation of transfer film by means of ‘contact resistance’. The measurements of friction temperatures were carried out by means of three thermocouples embedded in the material. The friction tests show that the friction coefficients of the FCB composites decrease almost monotonically with the increase of graphite content under different conditions; and the wear rates decrease overall compared with that of the homologous polymers, more obvious especially under severe conditions. The optical microscope, SEM, and XPS were adopted to study the worn surface morphologies and the transfer films. The main wear mechanism of the new composite is a three-body abrasion, caused and promoted by the plastic deformation, abrasive wear, and fatigue spalling. The oxidation of copper is the dominant chemical processes which occurred during the sliding process.