摘要:

AbstractThe aim of this study was to improve understanding of high‐temperature oxidation of base oils used in automobile engine oil formulations. Various oils were investigated: oils from the Middle East and the North Sea, with high and low aromatic and sulphur contents respectively; a hydro‐isomerised polyalphaolefin oil with no aromatic or sulphur content; and a hydrocracked oil of intermediate composition.The influence of the aromatic and sulphur content and composition of the oils on thermo‐oxidative degradation is investigated. These compounds give base oils natural protection from oxidation, but, under severe oxidation conditions, in the presence of a catalyst such as iron, which is always present in an engine, they become precursors of deposits.The action of two types of additive, radical inhibitors and hydroperoxide decomposers, was studied through oxygen consumption and thin‐film oxidation tests.The oxidation products were identified; these provide insight into the degradation processes of the compounds during oxidation. They show too the influence of these processes on the formation of oxidised volatile species, on the increase in viscosity of the oil, and on the formation of oxidised species of high molar mass which, as they condense, contribute to the formation of insoluble compounds and d

ISSN:0954-0075    

DOI:10.1002/ls.3010090102

出版商:John Wiley&Sons, Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe antioxidant properties of engine calcium sulphonate, phenate and salicylate detergent additives were investigated. Their influence on engine oil oxidation both in the presence of metallic copper, oil‐soluble copper compounds, and without any catalyst, was studied. The influence of the detergent type and its basicity on oil antioxidant properties was determined. The specific influence of the co‐operative action of detergent additives and zinc dithiophosphate on the antioxidant properties of engine oil formulations with these additives was established. The results obtained revealed various new patterns concerning the oil oxidation process, and allowed us to characterise the process of depletion of detergent additives during oil age

ISSN:0954-0075    

DOI:10.1002/ls.3010090103

出版商:John Wiley&Sons, Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractCreep transport is defined as the velocity of a mass of grease when it is subjected to vibrational and gravitational forces. The method developed to assess this, measured the time taken for the grease submitted to low frequency vibrations to creep, under the influence of gravity, a specified distance down a cylindrical tube. The vibrations were characteristic in frequency and amplitude to those commonly experienced by commercial rotating machinery. Vibrational excitation was found to have a widely varying effect on creep transport of grease, suggesting that this parameter may be important in the selection of greases for specific applications where vibration is present; in contrast, the NLGI number gave almost no indication as to the effect of vibration on a particular grease. A vibration number related to the creep rate is suggested for grease selection. The vibration number correlates to the yield stress of the grease, with higher yield stress correlating to higher creep rate. However, no correlations between creep rate and base oil viscosity or bleed rate were found.

ISSN:0954-0075    

DOI:10.1002/ls.3010090104

出版商:John Wiley&Sons, Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe addition of various extreme pressure and anti‐wear additives to lubricating oil is an important and effective way of reducing friction and wear. The application of chemico‐thermal treatments to material surfaces is another way to improve the tribological behaviour of rubbing pairs.The synergistic effects on the tribological behaviour of a tricresyl phosphate oil additive together with sulphurised, nitrided and oxy‐nitrided surfaces of 1045 steel were systematically studied on a ball‐on‐disc test machine. Good load bearing capacity and reduced friction and wear was obtained as a result. As well as presenting the promising results of this work here, the mechanism of this synergistic effect is discussed, based on micro‐analysis of the surface films by

ISSN:0954-0075    

DOI:10.1002/ls.3010090105

出版商:John Wiley&Sons, Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractWith changing engine design putting more emphasis on fuel economy, emissions control and low engine oil consumption, the quality levels of engine crank‐case oils are changing fast. With this in view, experimental work has been carried out towards the development of engine crankcase‐oil formulations meeting the required levels of oxidation stability.Three lubricant base‐stocks meeting the physico‐chemical characteristics of engine oils, prepared from lubricant streams obtained from different refined crude oils and one re‐refined engine oil base‐stock were used. The viscosity index of these base‐stocks ranged from 84 to 98, and carbon residue from 0.06 to 2.2. The antioxidant used in the formulation was of ZDDP type, and the detergents were calcium and barium sulphonates.The base‐stocks were evaluated using the IIP oxidation stability test, to determine their suitability in the formulation of engine crankcase oils. The base‐stocks were then dosed with additives, and tested again by the IIP Oxidation Stability Bench Test, for their additive response.The final formulations were then tested on a CRC‐L‐38 standard engine test prescribed in Indian Standard 13656:1993 for IC Engine Crankcase Oils with respect to bearing corrosion and piston deposit tendencies. It was observed that higher VI lubricant base‐stocks and the re‐refined engine oil base‐stock gave better test performance in both benc

ISSN:0954-0075    

DOI:10.1002/ls.3010090106

出版商:John Wiley&Sons, Ltd    

年代:1996

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010090101

出版商:John Wiley&Sons, Ltd    

年代:1996

数据来源: WILEY