摘要:

AbstractThe friction and wear behaviour of eight different SiCTiCTiB2composite materials, with a practically constant SiC:TiC ratio of 1 and an increasing amount of TiB2, was determined comparatively in oscillating sliding tests at room temperature under unlubricated conditions. The influence of the relative humidity (RH) of the surrounding air was investigated in tests in dry, normal, and moist air. All tests were performed against SiC balls and Al2O3balls as counterbodies. The friction was affected by RH but barely at all by the composition of the composites. The wear resistance of the composites was found to be improved considerably by addition of TiB2in the range 20–60%. The highest wear resistance of the system was found when Al2O3was used as the counterbody mat

ISSN:1354-4063    

DOI:10.1002/tt.3020090302

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractThe assessment of engine oil useful life is an important step in the development of future low‐phosphorus, catalyst‐compatible, and long‐drain engine oils. This paper describes the development and application of a new laboratory screening test, the Ford oil ageing test (FOAT), for the assessment of engine oil useful life. FOAT simulates the Sequence IIIE engine dynamometer test and evaluates oils on the basis of viscosity increase. It correlates well with both single‐ and double‐length Sequence IIIE test results. FOAT allows for inexpensive screening of candidate oils prior to engine tests and is currently being used in the evaluation of future low‐phosphorus engine oils. This comparative study has demonstrated that low‐phosphorus, catalyst‐compatible engine oils can be formulated to provide a similar useful life to current commercial

ISSN:1354-4063    

DOI:10.1002/tt.3020090303

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractThe tribological behaviour of oil‐lubricated steel‐alumina sliding pairs was investigated using a ball‐on‐disc tribometer at room temperature. Commercial bearing balls of 10 mm diameter were mated to 99.7% Al2O3discs, and additive‐free mineral oil was fed into the contact area. The sliding speed and the applied normal load were varied, and the initial surface roughness of the Al2O3disc was altered using different polishing and grinding procedures. The results showed that the surface roughness of the ceramic discs dominated the tribological behaviour under the given experimental conditions. The sliding speed as well as the normal load showed less effect on the friction behaviour, but the amount of wear depended strongly on the normal load. From the results it was concluded that improvement of the surface roughness and optimised surface machining of the ceramic material can be essential for improving the tribological performance for boundary‐lubricated steel‐ceramic

ISSN:1354-4063    

DOI:10.1002/tt.3020090304

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractHydroforming is a relatively new technology, which enables complex shaped hollow parts to be produced efficiently. Compared to alternative methods, this technology is characterised by significant potential advantages, such as complex shape production, lightweight design, high accuracy, and process integration.The tribological aspects of hydroforming are very significant, as friction influences all the main process parameters practically in a direct or indirect way. However, there is a paucity of information relating to hydroforming tribology. In most reports on this subject only qualitative data regarding the friction coefficient are given. However, for finite‐element method simulation and optimal process and tool design, quantitative data are indispensable.This paper describes an attempt to determine the coefficient of friction in both the elastic and plastic states of a workpiece during tube hydroforming processes. Push‐through tests were carried out in order to determine the coefficient of friction in the elastic state, and tube upsetting tests were conducted for the plastic state. Various commercial lubricants were used in the experime

ISSN:1354-4063    

DOI:10.1002/tt.3020090305

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractExperiments on molecular deposition (MD) films with and without alkyl terminal groups deposited on silicon wafers were conducted using nano‐indentation. It was found that MD films and alkyl‐terminated MD films exhibit a higher critical load and a lower coefficient of friction than the silicon substrate. The critical load increases with the number of layers, and the coefficients of friction of MD films with alkyl terminal groups are lower than those of the corresponding MD films with the same number of layers but without alkyl terminal gro

ISSN:1354-4063    

DOI:10.1002/tt.3020090306

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractThe increasing rotational speeds and the weight reduction of high‐performance internal combustion engines are accompanied by problems of lubrication, heat transfer, and vibration that are mostly negligible in medium‐ and low‐performance engines. To deal with such phenomena under demanding operating conditions necessitates a specific design. The dynamics of the power system between crankshaft and related sub‐components, e. g., bending and torsional vibrations of the connecting rod, ovalisation of the head and eye of the connecting rod, and vibrations of thin cylinder liners, are critical for the lubrication system in general, and for oil film pressure fields in particular. In some cases, no information on these features has existed until now, so no quantification of the variables involved has been possible. Over the last few years a systematic investigation has been performed to take into account the critical points and their fundamental importance in the design of such engines.The present paper considers some of the phenomena related to lubrication in high‐performance engines. The need is highlighted for further investigations using computational and experimental meth

ISSN:1354-4063    

DOI:10.1002/tt.3020090307

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractExperimental investigations have been carried out on the stress distribution on the outer surface of the outer race of conventional and double‐decker high‐precision bearings (DDHPBs). The investigations, in general, indicate that the overall level of stress variation on conventional bearings in various modes of loading under static conditions is greater than that of DDHPBs having an identical inner bore. The cyclic stress levels have been found to be higher for the outer race of conventional bearings compared to that of DDHPBs. Also, the frequency of stress cycles on the outer race of conventional bearings is greater than that of DDHPBs.A comparison of the stress distribution pattern indicates that, under identical loads, the ratio of deflection to indentation on the elements of DDHPBs and conventional bearings is less than unity. Also, under identical operating conditions, the ratio of stresses due to centrifugal forces on the elements of DDHPBs and conventional bearings of the same bore and outer diameter is less than unity. It is concluded that the life of DDHPBs as compared to conventional bearings should be longer under identical operating conditi

ISSN:1354-4063    

DOI:10.1002/tt.3020090308

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020090309

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020090310

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020090301

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY