摘要:

AbstractTo investigate and understand the tribological behaviour of high‐frequency tribosystems such as ultrasonic motors, a specific test method is necessary. This work reports on the construction of a test machine to evaluate the friction and wear behaviour of friction materials under ultrasonic fretting conditions, as well as giving some representative experimental results. Hard/soft (steel/polymer) and hard/hard (steel/alumina, alumina/alumina) couples were studied with respect to their application as contact materials in ultrasonic motors. Investigation of friction behaviour at high frequencies showed that friction‐induced vibrations lead to friction forces of much lower magnitude than predicted by quasistationary friction coefficients obtained for sliding friction. The wear behaviour is characterised by abrasive, adhesive, fatigue and oxidative mechanisms, depending on the mating materials. For polymeric friction materials, the influence of fibre reinforcement and the incorporation of PTFE as a solid lubricant were evaluated. The presence of PTFE resulted in a strong improvement of both friction and wear behavi

ISSN:1354-4063    

DOI:10.1002/tt.3020060102

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractA new method to investigate the tribocorrosion properties of metals and alloys has been developed with which the current density of a metal probe in an electrolyte under rubbing conditions can be measured. The electrochemical microcell consists of a microcapillary (inner diameter 0.84 mm); the rubbing partner is an Al2O3tube which rotates inside the microcapillary. Rotational speed, load and applied electrical potential can be varied, so that it is possible to analyse the corrosion rate during rubbing under various controlled conditions.With conventional tribocorrosion machines (e.g., pin‐on‐disc, ball‐on‐plate rig) and also with single‐scratch test machines, the current measured also derives from surface areas which are not undergoing mechanical wear. In the present method, the activation of specific surface areas under rubbing conditions, and subsequent repassivation, can be studied s

ISSN:1354-4063    

DOI:10.1002/tt.3020060103

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThe friction and wear behaviour of materials is often characterised in laboratory tests using a simple ball‐on‐flat configuration. From this type of test can be derived information useful in guiding the development of tribomaterials and in helping select candidate materials for specific applications. A large variety of tribotesting methods exists, and indeed several are not yet standardised. One of these methods is the oscillating sliding test, where a ball moves in relation to a disc, usually with small strokes. This method is almost non‐destructive and can be applied to very small specimens. One of the most important parameters in laboratory tests is the humidity of the surrounding air. Experimental results on the friction and wear characteristics of different ceramics tested against different ball materials at room temperature in oscillating sliding contact are presented here and discussed, taking into account the effects of the test duration, relative humidity, and counterbody mat

ISSN:1354-4063    

DOI:10.1002/tt.3020060104

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractWhen subject to low‐temperature conditions, the paraffins in a lubricant come out of solution to form structures that can impair oil flow. The size of the paraffinic crystals, and the strength of the three‐dimensional network they form, depend on physical parameters, such as temperature, cooling rate and soaking time, as well as on the chemical nature of the wax and of other components in the oil.To evaluate the ability of lubricants to flow under low‐temperature conditions, a number of test methods have been developed, from the simple pour‐point test (ASTM D‐97), to very sophisticated tests such as the MRV TP‐1 (ASTM D‐4864). In the early 1980s, a new technique, using the scanning Brookfield viscometer (ASTM D‐5133), was developed. This method has progressively gained acceptance by industry and is now part of the ILSAC GF‐2 specification. The scanning Brookfield technique provides a new approach to continuous measurement of the viscosity of engine lubricants at very low shear rates, with decreasing temperature. It is said to be unique in its ability to identify oils which develop gel structures at low temperature.After presenting background information on the scanning Brookfield viscometer, this paper examines its use with modern engine lubricants, and its ability to evaluate the effect of pour‐point depressants on the low‐temperature performance

ISSN:1354-4063    

DOI:10.1002/tt.3020060105

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractAutomotive gear oils, as typically used in rear axles, are normally evaluated in terms of their performance in full‐scale bench tests. One such test is the CRC L‐19/CRC L‐42 test, which is included in API and other specifications. The L‐19 test method is now obsolete, and the L‐42 is used basically to define GL‐5 level oils. An indigenous test method, IIP Method VAV‐382, has been developed at the Indian Institute of Petroleum on an Amsler machine, operating under sliding conditions between two discs, and is also included in the IS:1118‐92 specification for multi‐purpose gear oils for GL‐4 level oils. This method has been re‐examined to obtain better resolution of scuffing of the disc surfaces. The modified procedure has proved effective, and the procedure and results for various commercial oils are described in this paper, which shows the method to be effective for the evaluati

ISSN:1354-4063    

DOI:10.1002/tt.3020060106

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractIn this paper, two structural analysis methods, X‐ray diffraction and electron diffraction, are considered for their use in tribosystem diagnosis. It is shown that, for certain applied tribological problems, such as determination of friction conditions and type of wear regime, estimation of running‐in period, selection of optimum wear‐resistant materials, and of suitable conditions of friction and wear, these methods can be used in addition to more conventional tribotesting and tribodiagnostic methods.A study of the structure of certain friction pair materials and wear particles was conducted. X‐ray investigations of the surface layers of the friction pair materials showed that structural characteristics, such as broadening and intensity of diffraction lines, can be used in the estimation of friction conditions. Examples of the choice of structurally wear‐resistant engineering materials, and of suitable friction conditions, are given. The study of wear particles produced under different friction conditions shows that these particles vary not only in form and dimensions, but also in phase composition. This provides important additional information for friction and wear process diagnostics. The method involves electron diffraction analysis of isolated wear particles, which allows us to characterise the wear processes under friction conditions. It is shown that a definite phase composition, the fineness of wear particles, and the quantitative ratio of each of the wear product phases, can be characterised for different wear types. Some useful applications of these investigative methods for analysis of the wear nature of friction pairs are

ISSN:1354-4063    

DOI:10.1002/tt.3020060107

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020060108

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020060109

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020060101

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY