摘要:

AbstractThe antiwear properties of five zinc dialkyldithiophosphates, which differed in thermal stability, were evaluated in a 4‐ball machine by a preliminary wear track formation method. After testing the additives, the wear resistance of the films formed was measured by the increase in preliminary wear scar diameter over that of the additive‐free oil. IR spectroscopy was then used to study the transformation products of additives after thermostatic testing at between 100 and 240°C on steel surfaces, where the interaction products were evaluated by electrode potential method. The interaction of the decomposition products of dithi‐ophosphates with metal surfaces was found to be followed by a change in electrode potential. For the tested additives, a relationship is shown between antiwear effectiveness of the film on a friction track during tribological tests and the electrode potential value of the steel sample. Different parts of the relationship between the electrode potential and temperature relate to different stages of dithiophosphate decomposition measured by IR spectroscopy. It can be said that chemical modification of the steel surface which produces an improvement of antiwear properties, starts at the decomposition temperature of the dithiophosphate neutra

ISSN:0954-0075    

DOI:10.1002/ls.3010060202

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe mechanisms governing the influence of copper additives (powders, oxides, organic and inorganic salts, complex compounds) on tribological, rheological and basic physical properties of greases with various thickeners (lithium, complex lithium, complex aluminium and polyurea) are discussed. The copper plating effect was found to occur only under EP conditions. The physical and chemical patterns of copper‐containing grease additives under antiwear and extreme pressure conditions are discussed together with rational application alternatives in friction couples of equipment and machiner

ISSN:0954-0075    

DOI:10.1002/ls.3010060203

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe primary objective of this research was to develop relationships which predict tool wear from measured cutting forces. Different cutting speeds and feed rates were examined. The workpiece materials used were a medium‐carbon steel and a titanium alloy. A synthetic cutting fluid was used with a 9.525 mm drill and a 6.350 mm drill, for drilling the medium‐carbon steel and the titanium alloy, respectively.Preliminary testing was conducted to find the optimal values for cutting speeds and feed rates. The main drilling tests were performed using the cutting conditions resulting from the preliminary tests. Statistical analysis of the results of the main drilling tests showed that the axial force was significant at the 5 per cent level in models for both materials. It also showed that the moment about the vertical axis was significant at the 5 percent and the 15 per cent levels in the models for the titanium alloy and the medium‐carbon steel, respectively. The model for the smaller holes drilled into the more homogeneous material, the titanium alloy, was more accurate in predicting tool

ISSN:0954-0075    

DOI:10.1002/ls.3010060204

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe rheological behaviour of several multigrade oils formulated with four different polymer‐type viscosity index (VI) improvers was experimentally studied at different shear rates ranging from 1000S−1to 35,000S1and at both VI reference temperatures of 40°C and 100°C. The investigation was an attempt to assess the effect of each polymer addition on the viscosity‐temperature relationship, as related to its chemical type and to the shear rate applied. It was found that the viscosity loss with increasing shear rate is greater for hydrocarbon polymer types than for methacrylate, especially at low temperatures. It was also found that the viscosity index is affected by the shear rate as well as by the type and concentration of polymer additive; its significance is thus linked with the condition under which it is determined and cannot be used as an absolute criterion for the appraisal of multigrade oil perf

ISSN:0954-0075    

DOI:10.1002/ls.3010060205

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper deals with the analysis of the influence of base oil viscosity on the ability of ZDDP‐containing lubricants to form protective layers (especially antiwear layers). The chemical structure of additives used was characterised according to their thermal stability, determined by differential scanning calorimetry (DSC). The additives were added to base oils of various viscosities. The prepared lubricants were tested using a four‐ball machine, and analysed by DSC.The relationships between base oil viscosity and seizure load (Pt), weld load (Pw) and DSC test results are presented and discussed. The mechanism of interaction between ZDDP and the base oils was analysed by the use of a mathematical mo

ISSN:0954-0075    

DOI:10.1002/ls.3010060206

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper describes an experimental study of hydrodynamic lubrication in wire drawing in which different types of lubricants (straight oils, emulsions and grease) are used. The experiments were conducted on a specially designed laboratory wiredrawing test rig, to assess the frictional force and film thickness, while drawing an aluminium wire at different speeds. Hydro‐dynamic performance, including frictional force and film thickness, were measured and plotted graphically, showing lubricant and drawing speed as the main influences.Results indicate that the frictional force decreased and the oil film thickness increased using straight oils with high viscosity at high drawing spee

ISSN:0954-0075    

DOI:10.1002/ls.3010060207

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010060208

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010060201

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY