摘要:

AbstractRecent advances made in the chemistry and technology of nano‐metric inorganic particles allow the synthesis of various metal oxides, chalcogenides, phosphates, and so on. Surface modification of nanoparticles in some cases allows the formation of stable dispersions in liquid hydrocarbons. The state of the art in the field of inorganic nanoparticle synthesis and their application in tribology are discussed in this paper. Special attention is paid to the synthesis of surface‐capped and bare molybdenum sulphide nanoparticles and to the testing thereof as friction‐modifying additives for liquid lubricants. Differences in the mechanism of action of MoSxnanoparticles and molecular molybdenum complexes (e.g., molybdenum dithiocarbamate) are discussed. Future trends in the use of inorganic nanoparticles as lubricant additives are sugg

ISSN:0954-0075    

DOI:10.1002/ls.3010170202

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY

摘要:

AbstractIn advanced fuel‐efficient engine oils containing molybdenum dialkyldithiocarbamate, Mo(dtc)2, as a friction‐reducing additive, the friction‐reducing capability is gradually depleted with mileage accumulation and is dependent on the presence of other additives, such as zinc dialkyldithiophosphate, Zn(dtp)2. Indeed, it has been shown that the loss of the friction‐reducing capability of Mo(dtc)2coincides with the depletion of Zn(dtp)2. The next generation of oils will specify a lower phosphorus content (e.g., 0.08% in ILSAC GF‐4 and even lower in the specification after GF‐4) to reduce the detrimental effects of phosphorus on catalyst systems. This will necessitate the use of less Zn(dtp)2, which could have an adverse effect on the retention of friction‐reducing capability.The aim of this study was to determine if the retention of friction‐reducing capability could be maintained or even increased at 0.05% phosphorus with newer molybdenum trinuclear, Mo3S7(dtc)4, additives. To facilitate the study, a modified laboratory‐based ageing test was developed which correlated with the loss of friction‐reducing capability in the Sequence VIB engine test. This ageing test was used to evaluate model blends of Mo3S7(dtc)4with Zn(dtp)2at 0.05% phosphorus and added antioxidants. The results indicate that it is possible to extend the retention of friction‐reducing capability. However, whether or not it can be extended beyond the current drain intervals is s

ISSN:0954-0075    

DOI:10.1002/ls.3010170203

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY

摘要:

AbstractThe structure and the nano‐friction behaviour of a new kind of ultrathin film, a molecular deposition (MD) film, on an Au substrate were studied. The MD film is formed by the electrostatic attraction between opposite charges of cationic and anionic compounds, and a multilayer film can be built through alternating deposition of bipolar cationic and anionic compounds. Monolayer, bilayer, trilayer, and tetralayer MD films on Au substrates were examined. MD films with an alkyl terminal group were also investigated. It was found that while the MD film on an Au substrate reduced the friction, its nano‐friction behaviour was unstable because of the active terminal group. However, if the MD film was formed with an alkyl terminal group, its nano‐friction behaviour became stable and its friction decreased markedly. Therefore, this film termination method could contribute to the nano‐tribological application of M

ISSN:0954-0075    

DOI:10.1002/ls.3010170204

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY

摘要:

AbstractA mineral oil of low viscosity was additivated with different concentrations of low‐density polyethylene. The wear behaviour of the additivated samples and the base oil was evaluated using a four‐ball wear tester at constant speed and variable load. Steel and ceramic (silicon nitride) were chosen for the balls. The scuffing resistance of the ceramic balls was higher than that of the steel balls. No scuffing appeared in the case of an upper steel ball in contact with lower ceramic balls. As far as the minimum wear‐scar diameter on the lower balls was concerned, an optimum concentration of polymer added to the base oil was found from the experimental data, for both types of ball. For the systems investigated, the optimum concentration was about 1.0% polyeth

ISSN:0954-0075    

DOI:10.1002/ls.3010170205

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY

摘要:

AbstractViscosity‐pressure‐temperature relations for paraffinic mineral base oils at pressures up to 0.7 GPa and temperatures between 30 and 90°C were determined using a falling‐ball‐type viscometer. The oils used were solvent refined oils, hydrocracked oils, and an oil produced by a wax isomerisation process. The viscosity at pressures higher than those possible with the viscometer was then derived by applying a simplified solution to the traction curves determined using an elastohydrodynamic disc‐on‐ball tester. When the measured viscosity and the calculated viscosity were plotted against pressure, for the oils with a viscosity index higher than 120 the viscosity derived from traction measurements followed the curve extrapolated to the high‐pressure region using either the Yasutomi or Roelands equations (the parameters for which were obtained using the viscometer). However, the calculated viscosity for the lower‐viscosity‐index oils deviated upwards from the

ISSN:0954-0075    

DOI:10.1002/ls.3010170206

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY

摘要:

AbstractEmulsions are complex systems frequently encountered in our daily lives and in most industrial sectors, including the oil industry. An understanding of the mechanisms of emulsion formation is essential both to create them and to treat them. The present work describes the main phenomena that come into play in emulsifying. The break‐up of droplets in either laminar or turbulent flow is discussed, and certain correlations, from which the diameter of the droplets formed can be predicted, are given. The role of surfactants is also examined, as are the typical time scales of the various processes involve

ISSN:0954-0075    

DOI:10.1002/ls.3010170207

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010170201

出版商:John Wiley&Sons, Ltd    

年代:2005

数据来源: WILEY