Bao Shangguan

The Tribological and Mechanical Properties of Pdcpd/Pew Composites Prepared by Reaction Injection Moulding

In order to improve mechanical performance and wear resistance of polydicyclopentadiene (PDCPD) by convenient methods and technologies, novel PDCPD/polyethylene wax (PEW) composites were prepared by in-situ polymerization in a simulated reaction injection moulding. Studies on the mechanical and tribological properties of the composites were carried out. The bending strength and hardness of PDCPD/PEW composites significantly improved compared with neat PDCPD. The incorporation of PEW in PDCPD greatly enhanced the wear resistance and reduced the friction coefficients. The wear mass loss and friction coefficients for PDCPD/ PEW composites decreased continuously in the range of our experiments. The SEM micrographs of the worn surface showed the friction and wear mechanism of PDCPD.

High-Speed Dry Tribological Behaviors of CrNiMo Steel in Nitrogen and Oxygen Atmospheres

Abstract: In this article, the high-speed dry sliding tribological behaviors of CrNiMo steel against brass in nitrogen and oxygen atmospheres are investigated using a pin-on-disc tribometer. The worn surface is characterized by scanning electron microscopy and electron dispersion spectrums analysis. The wear mechanisms of CrNiMo steel are also analyzed. The results indicate that the tribological properties of CrNiMo steel are coincidental with the law of dry sliding of metal, where the friction coefficients decreases with an increase in sliding speed and with normal load. However, the atmosphere has obvious effects on the tribological properties of CrNiMo steel. In the sliding process, friction heat plays an important role on the tribological properties of materials in high-speed dry friction. The high-speed wear mechanism of CrNiMo steel varies at different atmospheres. In a nitrogen atmosphere, the wear mechanism of CrNiMo steel is mainly characterized by adhesion at a lower speed and load. When the speed and load are increased, melting trace is found in the worn surface accompanied by an abrasive wear. In an oxygen atmosphere, the mechanism is characterized by adhesion at a lower speed and load; with an increase in speed and load, it gradually transformed into oxidation wear and abrasive wear. The difference of the wear mechanisms in the different atmospheres and test parameters is primarily due to the transfer films formed on the contact surfaces of the sliding pairs. In our experimental conditions, the surface film is mainly the metal film in nitrogen, whereas, it is the oxide film in oxygen.

A Novel Model of Steady-State Sliding Wear with Electrical Current

A novel model of steady-state sliding wear with electrical current was created, which gives an accurate relational expression of three factors (electrical current, sliding velocity and contact pressure) and wear rate of the pin material. The experiments were carried out on the couple of QCr0.5 against copper-based powder metallurgical materials. The results show that the model is accurate and it is able to clearly show the influence of electrical current, sliding velocity and contact pressure on wear rate of pin.

Influence of Contacting Pressure on Current Stability and Tribological Properties of CPMM Collector Materials against Cu/Cr Alloy under High Sliding Speed with Electric Current

Dry sliding tests with electric current were carried out on a pin-on-disc system tribometer in this study, where copper-base powder metallurgy material and copper alloy QCr0.5 were used as the pin and the disc respectively. The researches were aimed at exploring relation between tribological properties and current stability of the couple under different loads. The results indicate that the current stability and friction coefficient increases with current and load. Moreover, co-effect between the current stability and tribological behavior has been found, which behaves in the way that the higher the current stability, the higher dynamic current collection capability and tribological properties.