Poly(l‐lysine)‐graft‐poly(ethylene glycol): a versatile aqueous lubricant additive for tribosystems involving thermoplastics

The adsorption and aqueous lubricating behaviour of poly(l ‐lysine)‐graft‐poly(ethylene glycol) (PLL‐g‐PEG) have been investigated for tribopairs involving thermoplastic materials, including polypropylene, polyamide‐6,6 and polyethylene. A major finding is that PLL‐g‐PEG adsorbs onto both hydrophobic, non‐polar surfaces and hydrophilic, polar (negatively charged) surfaces from aqueous solution, and thus plays as a very unique and effective aqueous boundary lubricant additive for the sliding contact of thermoplastics against themselves as well as against many hydrophilic, polar materials, including metals (e.g. stainless steel) or ceramics (e.g. zirconia, ZrO₂). Copyright © 2007 John Wiley & Sons, Ltd.     

The application of convergent beam electron diffraction (CBED) analysis on transformation‐induced plasticity (TRIP) steels

Convergent beam electron diffraction (CBED) in transmission electron microscopy (TEM) was applied to determine local carbon concentrations in low‐carbon transformation‐induced plasticity (TRIP) steels. High‐order Laue‐zone (HOLZ) lines were experimentally obtained for comparison with simulation results. A new procedure for calculating carbon content is thus proposed. Retained austenite (RA) is classified into three types by morphology; the relationship between the carbon content and the corresponding RA morphology is discussed based on CBED results. Furthermore, results of X‐Ray diffractometry measurements are also used for comparison.     

Tribological performance of poly(sodium 4‐styrenesulphonate) as additive in water–glycol hydraulic fluid

The tribological behaviour of poly(sodium 4‐styrenesulphonate) (PSS) as additive in the base fluid of water–glycol hydraulic fluid was evaluated with four‐ball machine and Optimol SRV‐IV (Optimol Instruments, Munich, Germany) oscillating friction and wear tester, and its viscosity‐enhancing performance was also investigated. The results show that PSS exhibits excellent friction‐reducing and anti‐wear properties in the base fluid and can significantly improve the latter's welding load and viscosity. The worn surfaces were characterised by scanning electron microscope and X‐ray photoelectron spectroscopy. The analytical results of typical elements on the worn surfaces demonstrate that PSS molecules adsorb on the rubbing surface and form a stable chemically absorbed film through the interactions between the sulphonate anions and surface metallic atoms during the sliding process, which contributed to improve the tribological properties of the base fluid. Copyright © 2012 John Wiley & Sons, Ltd.