摘要:

AbstractThe load‐carrying capacity, antiwear and friction reduction properties of an S,P‐containing benzotriazole derivative (BMDDP) added to a synthetic lubricant (pentaerythritol ester) were evaluated using a four‐ball test machine. The results when compared with those of tricresyl phosphate (TCP) and zinc dialkyldithiophosphate (ZDDP) show that, in pentaerythritol ester, the novel compound (BMDDP) is an excellent multifunctional additive, which possesses better load‐carrying capacity, antiwear and friction reduction properties than either TCP or ZDDP. The rubbed surfaces were analysed using XPS and EPMA, and the antiwear mechanism is di

ISSN:0265-6582    

DOI:10.1002/jsl.3000150402

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThe authors have studied the possibility of using Crambe abyssinicaoil as a starting material for synthetic lubricants, and in this paper the procedures for the preparation of monoesters from methyl, ethyl, isopropyl, and 2‐ethylhexyl alcohol, as well as diesters from neopentylglycol, triesters from trimethylolpropane and tetraesters from pentaerythritol, are described. The different reactions were set up using free fatty acids, methyl esters, andCrambeoil as starting materials. All reactions were carried out in a solvent‐free medium, using normally available catalysts and under experimental conditions which could easily be scaled up to industrial level. All the products obtained, along with the refinedCrambe abyssinicaoil used as a reference, were analysed for viscosity, viscosity index, low‐temperature behaviour and oxidative and hydrolytic stability. Results of tests, such as four‐ball machine and Noack, are reported. The results show that several products covering a wide range of different applications can be obtained from the basicCrambe abyssinicaoil, and, furthermore, the chemical modification of theCrambe abyssinicaoil can, in some cases, improve thermal and hydrolytic sensitivity and even the tribological pro

ISSN:0265-6582    

DOI:10.1002/jsl.3000150403

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractStar‐shaped alkylaromatic hydrocarbons consisting of oligomeric naphthalene cores and long straight‐chain alkyl arms have been synthesised using a one‐pot method:Where 1‐alkene is 1‐hexene, 1‐octene, 1‐decene, 1‐dodecene, 1‐tetradecene, 1‐hexadecene, and 1‐octadecene, respectively. Different linear 1‐alkenes with increasing chain length have been reacted with naphthalene oligomers in an identical way, and the properties of the total products compared and related to the chain length of the alkylating normal 1‐alkene. Consequent to this, increases in M̌n, (= 550–1900), viscosity indexes (90–161), pour points (—24 to + 17°C), flash points (210–330°C), and oxidation resistance, could be observed. These products exhibited properties good enough to be suitable for use as lu

ISSN:0265-6582    

DOI:10.1002/jsl.3000150404

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThis work has evaluated the influence of load and type of lubricant on the thickness of the elastohydrodynamic (EHD) film and the rolling‐contact fatigue lives of AISI 52100 steel balls. The lubricants studied have various viscosities and included two mineral oils and five synthetic oils from three families. Firstly, the central film thickness was determined in order to predict the lubrication regime. The stress—number of cycles fatigue curves were then calculated by means of Weibull plots, and the fatigue mechanism was evaluated.The test machine used for the analysis was a Seta‐Shell 1980 four‐ball EP lubricant tester. The 12.7 mm diameter test balls were made from a single batch of carbon‐vacuum‐deoxidised AISI 52100 steel with hardness RC65.Elastohydrodynamic film thickness estimation was carried out using pressure—viscosity coefficients (a). In this study, to calculate (X), a new interferometric technique, ultrathin film interferometry, was employed to measure the film thickness. A practical method was developed for evaluating EHD, mixed film, and solid lubrication processes. Micrographic mapping and energy dispersive spectroscopy (EDS) were used to analyse the rolling track of t

ISSN:0265-6582    

DOI:10.1002/jsl.3000150405

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractSince the macroscopic properties of materials are relevant to their micro structure, the detection of microscopic defects or their changes in size and concentration is an interesting topic in materials science. The positron annihilation lifetime (PAL) method used here is established as a unique technique that can provide information about the size and concentration of free volume holes directly without significantly intervening in the bulk properties of the specimens. To our knowledge, this is the first time that PAL techniques have been used to study the wear mechanism of macromolecular tribomaterials. Here we present the results of a study in which the correlation between the fretting wear behaviour of polytetrafluorethylene (PTFE) and the changes in its free volume size and concentration in amorphous‐crystal interface regions was found to be δω =A.δτ3, where δω is the wear loss of PTFE under fretting wear conditions, A is a constant, and δτ3represents the relative change in the third lifetime components after the friction test. The results indicate that fretting mainly influences the characteristics of atomic‐scale free volume holes in the amorphous‐crystal region in PTFE, and under high‐load fretting wear conditions the ductile polymer PTFE possesses a self‐curing function for its defect‐free

ISSN:0265-6582    

DOI:10.1002/jsl.3000150406

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000150407

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000150408

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000150409

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000150401

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY