This is an Accepted Manuscript of an article published by Taylor & Francis in Tribology Transactions on 10 January 2013, available online: http://www.tandfonline.com/doi/abs/10.1080/10402004.2012.748948.This paper presents an investigation on the potential tribological properties of the water-based cerium dioxide nanofluids. The nanofluids with different nanoparticle concentrations were prepared in a materials laboratory. A stable dispersion of nanoparticles in the fluids was achieved with an appropriate percentage of surfactant sorbitan monostearate. The stability of particle dispersion was studied using a Zeta-potential measuring device. Additive conglomerate size in the nanofluids was measured using Dynamic Light Scattering (DLS) device. It has been observed that the dispersibility of nanoparticles played an important role in the frictional properties of the nanofluids. The tribological properties of the water-based nanofluids were evaluated using a Pin-on-disc tester under different loading conditions. A significant improvement on tribological properties of the water-based cerium dioxide nanofluids was observed. The worn surfaces of the contact elements were characterised using SEM and a Nano-tester. According to the test results, the significant reductions of the friction coefficient and the anti-wear property of water-based cerium dioxide nanofluids are attributed to the deposition of nanoparticles on worn contact surfaces

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This article presents an investigation on the tribological properties of zinc borate ultrafine powder (ZBUP) employed as a lubricant additive in sunflower oil. The stable dispersions of 0.5, 1, and 2 wt% ZBUP in sunflower oil were achieved using an ultrasonic homogenizer. Both a four-ball tester and a pin-on-disc tester were employed to evaluate the antiwear and friction reduction capabilities of ZBUP. Tribofilms with a dark color were generated on the worn surfaces and showed good contrast with the substrate. The worn surface with different morphologies reflected as color alterations on the worn surface were observed when different lubricants were applied. The morphology and elemental analysis of the worn surfaces were studied using atomic force microscopy (AFM) and scanning electronic microscopy (SEM). Mechanical properties of the tribofilms and substrates were studied with a nano-indentation tester. Test results suggest that tribofilms generated on the worn surface have relatively low hardness compared with the steel substrate. The substrates on the worn surfaces lubricated in sunflower oil with the powder demonstrated higher hardness than the substrate lubricated with pure sunflower oil due to the possible tribochemical reaction between the zinc borate additive and substrate. The combination of sunflower oil with 0.5% ZBUP delivered the most balanced performance in friction and wear reduction. This study has demonstrated the possibility of application of this industrially applicable solid lubricant additive (zinc borate) with a decomposable vegetable-based lubricant oil.

Phosphonate-functionalized ionic liquid (PFIL) is employed as a multifunctional additive to the base electrolyte mixture consisting of ethylene carbonate, dimethyl carbonate and LiPF 6 . Addition of PFIL (5 wt%) significantly improves the cyclic stability and rate capability of LiCoO 2 cathode performed between 3.0 and 4.3 V (vs Li/Li + ), and decreases the flammability of the base electrolyte as well. Electrochemical studies indicate that PFIL is preferentially oxidized on cathode to form robust cathode electrolyte interface (CEI), which contributes to the enhanced cyclic stability and rate capability. Morphological and surface analysis on the cycled cathodes also reveal that PFIL is a key component for the formation of thin CEI film and retention of structural integrity of cathode material. Comparison experiments verify that chemically linking between ionicity and phosphorus functionality is indispensable for the enhanced performance. Additives of individual nonfunctionalized ionic liquid, neutral phosphonate, or their mixture all fail to improve the electrochemical performances.[a] J.

A phosphonate functionalized imidazolium ionic liquid (PFIL) is synthesized and studied as an electrolyte additive for lithium ion batteries. The Li/LiFePO4 cells with addition of PFIL shows superior electrochemical performance, including an increased initial Coulombic efficiency, better capacity retention, and improved rate capability. The electrochemical mechanism of PFIL used in high‐performance batteries is investigated by using fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Our experimental result reveals that the phosphonate groups are stronger donors than carbonate groups, thus change the solvation environment of lithium ions by competitive coordination, assisting the transferring of lithium ions. Therefore, an excellent cyclability and superior rate capability with PFIL‐based electrolyte could be explained by enhanced mobility lithium ions via coordination to phosphonate groups on imidazolium cations. This work displays that PFIL‐based electrolyte systems can be considerable potential candidates for the applications in high‐performance Li‐ion batteries.