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This study aims to compare the friction and wear behaviors of Fe_68.3C_6.9Si_2.5 B_6.7P_8.8Cr_2.2Al_2.1Mo_2.5 bulk metallic glass (BMG) under sliding using dry, deionized water-lubricated and oil-lubricated conditions. The comparison was performed using a unidirectional ball-on-flat tribometer under different applied loads, and the results were compared to the properties of a conventional material, SUJ2. Fe-based BMG materials have recently been attracting a great deal of attention for prospective engineering applications.

As a part of the development of Fe-based BMGs that can be cost-effectively produced in large quantities, an Fe-based BMG Fe_68.8C_7.0Si_3.5B_5.0P_9.6 Cr_2.1Mo_2.0Al_2.0 with high glass forming ability was fabricated. In the present study, the friction and wear properties of Fe-based BMG has been comparatively evaluated under dry sliding, deionized water- and oil-lubricated conditions using a unidirectional ball-on-flat tribometer under different applied loads, and the results were compared to the properties of conventional material SUJ2.

The results show that the Fe-based BMG had better friction performance than the conventional material. Both the friction coefficient and wear mass loss increased with increasing load. The sliding wear mechanism of the BMG changed with the sliding conditions. Under dry sliding conditions, the wear scar of the Fe-based BMG was characterized by abrasive wear, plastic deformation, micro-cracks and peeling-off wear. Under water- and oil-lubricated conditions, the wear scar was mainly characterized by abrasive wear and micro-cutting.

In this investigation, the authors developed a new BMG alloy Fe_68.8C_7.0Si_3.5B_5.0P_9.6Cr_2.1Mo_2.0Al_2.0 to improve the friction and wear performance under dry sliding, deionized water- and oil- lubricated conditions.

Aerostatic porous bearings are important for guide rails and spindles. It is well-known that flow restrictors made of porous materials offer major advantages over conventional restrictors in such bearings, including design and manufacturing, load-carrying capacity, stiffness, damping and dynamic stability. Thus, this work numerically investigates the effect of the arc on a new combined annular-thrust aerostatic porous bearing.

The static characteristics of an annular-thrust aerostatic porous bearing were studied using a fast finite element scheme. The pressure distribution, radial load and thrust load were analyzed as functions of the arc, permeability and eccentricity.

The results reveal that the radial load achieves maximal values at an optimal arc value between 200 and 300, and the thrust load increases monotonically with increasing arc.

This work developed a new combined annular-thrust aerostatic porous bearing to investigate the effect of arc on the annular-thrust aerostatic porous bearings to increase the load-carrying capacity.

The purpose of this paper is to investigate and discuss the effect of multi-shape laser surface texturing (LST) steel surfaces on tribological performance.

The textured surface with some specific formula arrays was fabricated by laser ablation process by combining patterns of circles and triangles, circles and squares and circles and ellipses. The tribological test was performed by a flat-on-flat tribometer under dry and lubrication conditions, and results were compared with that of untextured surface.

The results showed that the textured surface had better friction coefficient performance than the untextured surface due to hydrodynamic lubrication effect. Through an increase in sliding speed, the beneficial effect of LST performance was achieved under dry and lubrication conditions.

This paper develops multi-shape LST steel surfaces for improving the friction and wear performance under dry and lubrication conditions.

The purpose of this paper is to study the possibility and validity of using radio frequency (RF) power argon (AR) ion plasma treatment to modify the surface of nitrile butadiene rubber (NBR) and the change in the chemical structure under various bias voltage. Using wear test, the authors also compared the friction and wear properties of untreated and treated NBR.

The hybrid RF-power sputtering system was used to generate RF Ar plasma to modify the surface of NBR specimens. The tribological properties were evaluated by ball-on-disc test using a load cell mounted on the ball holder.

It was found that the NBR surface treated by the Ar plasma improved the wettability, friction and wear performance than the untreated NBR. The ATR-IR analysis indicated that the improvement come from the oxygen based functional groups generated on the surface of NBR. The improvement of friction and wear resistance may also come from the formation of nanostructure surface.

In this study, the authors develop the RF AR ion plasma treatment at different bias voltage, and it has been used to modify the surface of NBR to increase the tribological performance.

The purpose of this paper is to investigate the effect of laser surface texturing on the tribological properties of polyimide composites and the output performance of traveling wave rotary ultrasonic motor.

The surface texturing on polyimide composites specimens were fabricated by laser ablation process of different dimple densities, and then the tribological properties were tested by a flat-on-flat tribometer under dry conditions. Finally, the output performance of the traveling wave rotary ultrasonic motor was tested to verify the effectiveness of dimples surface texturing.

The results show that surface texturing can greatly enhance the friction coefficient of contact interface, especially the specimen with a dimple density of 7.06 per cent exhibited the highest friction coefficient among the specimens. When the input voltage is 500 V, the output power, locked-rotor torque and output torque of ultrasonic motor with textured PI of 7.06 per cent dimple density as friction material at the speed of 100 r/min increased by 13.8, 19 and 12.8 per cent compared to that of the untextured PTFE, respectively. When the ultrasonic motor reverses, the output performance is increased by 20.9, 40.3 and 17.7 per cent, respectively.

Surface texturing is an effective way to improve the friction behavior of polyimide composites and then correspondingly enhance the energy conversion efficiency and output performance of the traveling wave rotary ultrasonic motor.