摘要:

AbstractSulphonate and phenate detergents are used in many modern oil formulations. Overbased sulphonates form micelles, whereas in overbased phenates the excess metal carbonate is incorporated in the molecule as a carbonate chain. This is the cause of broad unresolved peaks in the NMR spectra of these detergents. Hydrolysis removes the excess metal carbonate and converts the sulphonates and phenates to sulphonic acids and phenols respectively. Especially in the1H‐ and13C‐NMR spectra, a substantial resolution enhancement is achieved after hydrolysis. These spectra reveal much more structural information. One of the features that can be calculated from the13C‐NMR spectra is the mean alkyl chain length.In this study a number of commercially available sulphonate and phenate detergents have been investigated. For the sulphonates the alkyl chain length was found to range from 17–22 carbon atoms, and for the phenates the alkyl chain length proved to be approximately 9–12 carbon atoms. The phenate alkyl chains showed significantly more branching than those in the sulphonates.In the1H‐NMR spectra, the position of the acidic proton signals is influenced by the measurement temperature, water concentration and solvent. The effect of these parameters was studied in detail.A combination of sample preparation techniques, such as dialysis, and hydrolysis and spectroscopic techniques, such as IR and NMR, can be used successfully to characterise detergents in terms of their molecula

ISSN:0954-0075    

DOI:10.1002/ls.3010060102

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe performance of a reciprocating engine can be improved by reducing the friction between piston rings and cylinder liner, which significantly contributes to the mechanical friction losses of an engine.The friction force of a piston ring pack is calculated, based on hydrodynamic lubrication theory, for the piston rings. Calculations were carried out for three sets of conditions. Oil starvation is taken into consideration in the calculation of oil‐film behaviour for a ring pack. The friction characteristics of piston rings are evaluated using the frictional mean effective pressure.The friction force of a piston assembly is measured experimentally by an improved floating liner method. The effects of lubricant viscosity and engine speed on friction characteristics are investigated by both calculation and experimen

ISSN:0954-0075    

DOI:10.1002/ls.3010060103

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSix organic borates of different molecular chain length were synthesised, and the friction and wear properties of these borates as oil additives were evaluated using a Timken Tester. X‐ray photoelectron Spectroscopy (XPS) was used to study the surface composition and valence state of boron on the rubbed surfaces.It was found that the antiwear and friction reduction effects of the borates are significantly influenced by the molecular chain length. The longer the chain length, the lower the friction coefficient and wear, and the higher the failure load. XPS analyses of rubbed surfaces revealed that the binding energy of BISincreased after rubbing, but no pure B(OH)3and B2O3was generated. the load‐carrying capacity and the antiwear effect are probably related to the ratio of numbers of carbon atoms to numbers of boron atoms on the rubbed surfa

ISSN:0954-0075    

DOI:10.1002/ls.3010060104

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study is aimed at determining whether or not tribopolymerisation can occur under conditions of fretting contact. Using a high contact stress system consisting of oscillating metal balls loaded against flat steel discs, effects of various monomers on friction, wear, and surface film formation were determined. Monomers were used at 1% concentration in hexadecane. Under the conditions used (90N load, 40 Hz frequency, 300 μm amplitude, for 1 hour), the monomers tested reduced friction or wear or both. Fourier Transform Infrared (FTIR) analysis of the test specimens showed that organic material is presented in the wear scars and depends on the metal system used, the monomer structure, location within the track, and the method of cleaning the surface after a test. With Al‐on‐steel, the addition of 1% styrene to hexadecane reduced volumetric wear of the disc by 65%; furthermore, positive FTIR evidence of polystyrene in the wear track was obtained. But adimer acid/glycol monomer formed metal soaps, no polymer, and had little effect on wear under these conditions. These results support the hypotheses that addition‐type tribopolymerisation can be initiated by exoelectron emission. Additionally, it was found that not only does methyl methacrylate polymerise under the fretting conditions, but the polymer film formed also reacts with the friction contact surface.Taken as a whole, the results of this study of possible tribopolymerisation under fretting conditions support both major hypotheses, namely that: (i) for condensation‐type monomers, the most important factor is the temperature of the rubbing surfaces. (ii) For addition‐type monomers, it would appear that the effect of exoelectron emission can initiate surface polymerisation even at relatively low surface temperatures, e.g., 10–40°C above ambient. This is in agreement with the negative‐ion‐radical action mechanism (NIRAM) of boundary lubricant component.Finally, the results obtained in this study demonstrate that the principle of tribopolymerisation developed by Furey and Kajdas can be used as a novel and effective approach to designing specific molecular structures for boundary lubrication under various r

ISSN:0954-0075    

DOI:10.1002/ls.3010060105

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010060106

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010060101

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY