In-Situ Formed Al3Zr Compounds Reinforced Al Composites and Tribological Application

An Al3Zr-reinforced Al matrix composite using metal powders was fabricated via in-situ synthesis in vacuum; these were subjected to a pin-on-disc wear test with a SUS304 disc specimen under oil lubrication. The elemental mixture of Al and ZrH2 particles was sintered in vacuum for the in-situ-formed Al3Zr. ZrH2 particles were thermally decomposed in the reaction with the Al matrix to form hard Al3Zr intermetallic compounds. The friction coefficient and wear volume values of the Al–Al3Zr composites were significantly lower than those of the pure Al specimen. This is attributed to the uniform dispersion of Al3Zr particles in the Al matrix, which prevented the metallurgical bond from falling and blocked the direct contact between the Al matrix and SUS304 disc.

Polymeric Nanostructures for Prospective Tribological Application in Min-iaturized Devices: A Review

Background:: Tribological issues severely confound smooth operation of moving elements in actuators-based miniaturized devices e.g. micro-electro-mechanical systems. At micro/nano scales, surface forces namely adhesion and friction manifest strongly and oppose relative mechanical motion of actuator elements. Topographical modification of sur-faces via surface patterning has emerged as a potential route to mitigate surface forces at small-scales. Methods:: Capillary force lithography is a simple yet robust technique to fabricate polymer nanostructures with varying shapes/sizes. This paper presents a brief review on the capillary force lithography technique, its salient features and tribo-logical performance of nanostructures fabricated by the technique. Conclusion:: Capillary force lithography has several attractive salient features, in particular the ability of the technique to create polymer nanopatterns of varying shapes/sizes without the need for molds with different shapes/sizes. Polymer nanostructures fabricated by the technique effectively reduce surface forces at micro/nano-scales, and are of interest for tribological application in small-scale devices.

Utilization of TiO2/gC3N4 nanoadditive to boost oxidative properties of vegetable oil for tribological application

The emergence of vegetable oil as a promising alternative lubricant in the tribological application space has fueled research for making these oils as useful as mineral oils. Tribological modification of vegetable oil by the addition of TiO2/gC3N4 nanocomposite (as a nanoadditive) was studied here. The dispersion of the nanoadditive in the vegetable oil showed good oil dispersion stability without the addition of any surfactant. The tribological studies were conducted in a four-ball tester using ASTM standard D5183. In addition, the effect of temperature on tribological performance was also studied to understand the oxidation behavior of vegetable oil. The results showed a significant improvement in friction and wear properties of the optimized nano-oil. The mechanism behind the improvement in friction and wear properties is annotated in this paper.

Boundary Lubricating Properties of Black Phosphorus Nanosheets in Polyalphaolefin Oil

As a novel layered material, black phosphorus (BP) shows unexpected characteristics in many aspects including tribological application. In this work, BP was prepared through ball milling from red phosphorus (RP). The boundary lubricating properties of the BP nanosheets were investigated on a ball-on-disk tribometer as lubricating additives in polyalphaolefin oil. The micromorphologies, concentration, and composition of the typical chemical elements on the worn surfaces were measured by the 3D laser scanning microscope, scanning electron microscope, and X-ray photoelectron spectrometer, respectively. The results show that bulk BP can be found after RP was milled at 500 rpm for 36 h. The Raman intensity of the BP increased initially and then decreased with the increase in milling time, and the maximum intensity can be obtained at 60 h. The BP nanosheets displayed excellent antifriction and anti-wear performances as lubricating additives in PAO6 oil for steel/steel contact in boundary lubrication regime. The boundary lubrication mechanism of the BP nanosheets is dominated by the physical slippery effect of the laminated nanosheets and the tribofilm on the rubbing surfaces.