摘要:

AbstractThe purpose of this investigation is to understand the role of KMnO4as an oxidant additive on the lubrication properties of a soft metal + graphite composite system, under flat contact sliding conditions where the sliding surfaces interact less with the atmosphere. The sliding tests were made using a ring‐on‐disk machine, lubricated with Pb or Ag + graphite composite containing different amounts of KMnO4additive.The results showed that the addition of KMnO4in the composites reduced the friction in air up to temperatures of 500°C. The coefficient of friction was as low as 0.1. This is probably due to the fact that KMnO4decomposed during sliding to generate oxygen, which is effective in improving the lubricating ability of graphite. The optimum concentration of KMnO4in the solid lubricants (graphite + KMnO4) was 5–10 vol.%. After decomposition of all oxidant additive in the composite, the coefficient of friction of the composites, however, rose to 0

ISSN:0954-0075    

DOI:10.1002/ls.3010050202

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractColloidal dispersions of calcium carbonate stabilised by calcium alkylaryl sulphonates are detergent additives used in lubricant oils, and have particular effects on wear processes. In the present work, such additives were investigated using Small Angle X‐ray Scattering technique (SAXS). Different scattering intensity simulation and curve‐fitting programs were used to determine the size of the overbased calcium sulphonate particles and to characterise the interactions between them. In the additive oil (11 wt% CaCO3), the overbased calcium sulphonates appear as polydispersed micelles having an average calcium carbonate core radius of 2.0 nm. Moreover, an attractive potential between the micelles of less than kT has been observed. In order to investigate the effect of friction constraints on the additive, friction tests were performed on a rotative tribometer. Under specific conditions, there was a decrease in friction force arising from the formation of a viscous deposit. According to the differentanalyses, the viscous deposit contained more polydisperse particles, which did not have the same structure as those contained in the original additive. These particles consisted mainly of calcium carbonate. Some sulphonate chains were expelled from the friction zone. Moreover, the particles contained in the deposit interact with a potential on the order of 10 kT. Wide Angle X‐ray Scattering (WAXS) confirmed the presence of highly crystalline calcite. Moreover, the effects of pressure and the presence of water were studied. The pressure contributes neither to an increase in particle size nor to a crystallisation phenomenon. However, the presence of water in the additive oil alters the interactions between the micelles. The potential observed is 8.2 kT and suggests that the water is a responsible parameter for the agglomeration of micelles consisting of the viscous de

ISSN:0954-0075    

DOI:10.1002/ls.3010050203

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRadical scavenger, radical anion scavenger, and peroxide decomposer were added to aromatic hydrocarbons and phosphates in aromatic rings with and without side chain, and the effect of these inhibitors on tribopolymerisation and the lubrication characteristics of the aromatic compounds were investigated, in various atmospheres, in order to clarify the reaction mechanism. The aromatics of both hydrocarbons and phosphates with a methyl group in aromatic rings react readily at the rubbing surfaces to form polymer or polymer‐like products, improving the lubricating characteristics. The tribochemical reactions of alkylaromatic compounds is shown to differ from those of trialkyl or triarylphosphates. It was concluded that the reaction proceeds through the radical or radicalanion and via peroxide to cause polymerisatio

ISSN:0954-0075    

DOI:10.1002/ls.3010050204

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe role of oxygen in lubricated wear is discussed. Previous studies have shown that at low concentrations, oxygen can reduce wear, but at higher concentrations, it can increase wear. The situation is complicated by ZDTP antioxidants. The present paper reports experimental work aimed at elucidating the role of hydroperoxides ‐ whether they participate in the formation of wear‐resistant oxide films, if they (or peroxy radicals) are the main source of oxygen, and whether ZDTP‐hydroperoxide interactions in the wear zone are important in controlling

ISSN:0954-0075    

DOI:10.1002/ls.3010050205

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper reports work on the relationship of surface tension of ZDDP solutions to adsorption isotherms. The surface tension of the solutions varies with their composition, and information about adsorption, decomposition or other chemical changes of ZDDP in solution can be obtained from the correlation of solution concentration and surface tension. From this work, the authors conclude that adsorption of ZDDP on iron can occur at even low concentrations, increasing with temperature, and that decomposition, association and interaction between components may occur in solution at high temperatures.

ISSN:0954-0075    

DOI:10.1002/ls.3010050206

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010050201

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY