The wear behavior of aged Cu-Cr-Zr alloys dry sliding against a brass counterface were investigated on a pin-on-disk wear tester under electric current conditions. The worn surfaces of the aged Cu-Cr-Zr alloys were analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectrum (EDS). The results indicated that the aging treatments had an effect on the microstructure, hardness and wear resistance of Cu-Cr-Zr alloy. At the constant current density, the wear rate of Cu-Cr-Zr alloy decreased with aging temperature, and reached the minimum at 500℃, then increased with further increasing aging temperature. An appropriate aging treatment may improve the wear resistance of the materials due to the formation of fine, dispersive and coherent precipitates within the matrix. An increase in electrical current resulted in an increase in wear rate of both the Cu-Cr-Zr alloy pin, and the brass disk. Adhesive wear, abrasive wear and arc erosion were the dominant mechanisms during the electrical sliding processes. Compared with commercially used Cu-Ag alloy wire (CTHA110) under the same test conditions, the Cu-Cr-Zr alloy treated at 500℃ for 2 h exhibited much better wear resistance.

Tribological properties of carbon-nanotube-reinforced copper composites were investigated using a pin-on-disk test rig under dry conditions. The composites containing 4-16 vol% carbon nanotubes (CNTs) were fabricated by a powder-metallurgy technique. The tests were carried out at normal loads between 10 and 50 N, and the effect of volume fraction of CNTs on tribological behavior of the composites was examined. The composites revealed a low coefficient of friction compared with the copper matrix alloy. Due to the effects of the reinforcement and reduced friction, the wear rate of the composites decreased with increasing volume fraction of CNTs at low and intermediate loads. The composites with a high volume fraction of CNTs exhibited high porosity and their wear resistance decreased under high-load conditions.

Adhesion strength and high temperature wear behaviour of ion plating TiN composite coating with electric brush plating Ni-W interlayer deposited on a hot work die steel were investigated using a plate-on-ring test rig. The microstructure and wear characteristics of the coating were analyzed using XRD, TEM, SEM and EDS. The adhesion of the coating to the substrate was determined by scratch test. The results indicated that crystallization and precipitation-hardening in the electric brush plating Ni-W interlayer and formation of interface diffusion layer and duplex composite layer at the interface occurred due to thermal effects during TiN deposition. The Ni-W interlayer could provide an effective support for the TiN coating, thus the adhesion strength and hardness of the TiN composite coating increased significantly. In the temperature range 500-7008C, the TiN composite coating with Ni-W interlayer revealed high wear resistance as compared with the single TiN coating. The coefficient of friction and wear rate of the single TiN coating increased as the temperature increased, while the TiN composite coating exhibited the lowest coefficient of friction and wear rate at 6008C. Abrasive and adhesive wear were the predominant wear mechanisms of the coatings at elevated temperatures.

Ni-P-Carbon nanotube (CNT) composite coatings as well as Ni-P-SiC and Ni-P-graphite coatings were prepared by electroless plating. The tribological properties of these composite coatings were investigated using a ring-on-block test rig under lubricated condition. The Ni-P-CNT composite coatings exhibited not only high wear resistance but also low friction coefficient compared with the Ni-P-SiC and Ni-P-graphite composite coatings. The favorable effects of CNTs on the tribological properties of the electroless coatings are attributed to improved mechanical properties and unique topological structure of the hollow nanotubes. In addition to preventing the rough contact between the two mating metal surfaces, the shorter CNTs can easily slide or roll within the surfaces of friction pairs. Therefore, the wear rate and friction coefficient of Ni-P-CNT composite coatings can be substantially reduced.

The aligned film of amorphous carbon (a-C) nanorods was prepared by catalytic chemical vapor deposition (CCVD) on an anodic aluminum oxide (AAO) template at 650 8C. The morphology and microstructure of aligned film of amorphous carbon nanorods were examined by scanning electron microscopy (SEM) and Raman scattering spectroscopy. The friction and wear properties of aligned film of amorphous carbon nanorods on the AAO template in vacuum (1.12