摘要:

AbstractOne of the main problems in fretting wear research is accurate measurement of the very small wear volumes (in microgams) produced. Different techniques, with their own advantages and disadvantages, can be used. Classic wear techniques lack sensitivity and often fail to measure the fretting wear volumes at all, or are not accurate enough. The authors have developed a Thin Layer Activation (TLA) method for quantification of the fretting wear of steel surfaces. The same method can also be used to determine material transfer between wear specimens. In this paper, the different methods are reviewed, and their accuracy in terms of the fretting wear measurement of steel surfaces is discussed. It is concluded that TLA has relatively good reproducibility and accuracy in comparison with classic fretting wear measurement techniques, such as normal approach measurement and spherical cap modelling. Modern threedimensional profilometry has better reproducibility than TLA, but is afflicted by systematic errors because of the oxidation of the metal surface. The different methods emphasise different features of the fretting process, and it is advisable to use them together for measuring fretting wear; their combined use provides a better understanding of the fundamentals of the fretting wear process.

ISSN:1354-4063    

DOI:10.1002/tt.3020040202

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractModern engine tests that evaluate the anti‐wear properties of automotive engine oils are increasingly sophisticated and expensive, and often have relatively poor precision. The development of a simple, inexpensive, and reliable bench test to screen the anti‐wear properties of fully formulated engine oils prior to their testing in engines is therefore very attractive. Numerous methods already exist, but they typically measure wear only at the end of the test by measuring the consequences of wear. The present paper describes an alternative approach, its purpose being the comparative evaluation of the anti‐wear performance of lubricants throughout the test under variable load. A four‐ball machine was used as a test rig for this work, and was equipped with instruments allowing study of the oil bath temperature, load applied to the balls, and the displacement of the load lever arm.The work presented focuses on a test procedure containing the following important elements: pre‐ageing of oils, test start‐up at very low load, incremental increases in load, stepwise increase in load, with each step sufficiently long to allow system equilibrium.Recording and analysis of the temperature and arm displacement curves permit the recognition of two distinct forms of wear: slow and gradual abrasive wear, and sudden and intense adhesive wear (scuffing). The presence and the intensity of the latter were found to have a direct relation with the anti‐wear performance of candidate oils in the API Sequence VE engine test. The procedure ranked oils correctly in relation to their dithiophosphate concentration, correctly distinguished secondary and primary zinc dithiophosphates and, more interestingly, predicted the positive effects of some ashless anti‐wear additives in accordance with results obtained in

ISSN:1354-4063    

DOI:10.1002/tt.3020040203

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractThe ‘disc‐on‐flat’ system has been used for testing wear under starved lubrication conditions. The rotating discs were made of a carbon steel, the surface finish of the discs being ground. Some of the discs were treated by ‘vibrogrooving’, to form regular microrelief. The flat counterface was made of a ground copper alloy. An industrial oil was used as a lubricant in a one‐drop test procedure. Microreliefs of a non‐touching design with a relative groove area of 34% caused less wear than microreliefs of a touching type with a relative groove area of 50%, whereas the wear caused by the ground disc was high, with seizure after 200–250 m of sliding distance. A one‐drop disc‐on‐cylinder test also showed that the wear caused by discs with regular microrelief was considerably less than that caused by discs treated by conventional finishin

ISSN:1354-4063    

DOI:10.1002/tt.3020040204

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractTwo tests for evaluating an engine lubricant's tendency to form deposits at high temperature have been developed by a working group of the GFC,Groupement Français de Coordination (French Coordination Group).set up to establish laboratory pre‐selection tests. The first is a new static microcoking test where the oil is deposited on an aluminium alloy plate and submitted to thermal conditions similar to those found in the piston ring zone of an IC engine. The results are analysed to determine the temperature at the oil's thermal stability limit and to evaluate the quantity and nature of the deposits in the form of varnish, according to a grading system based on the CEC M‐02‐A‐78 method of gauging engine cleanliness. The second is an improved panel coking test in which a thin film of oil of a given volume is fed on to a stainless steel panel, at high temperature, and the deposits formed at the end of the test are evaluated, again using the CEC rating method, in terms of quantity and type (carbon or varnish).In addition, a video system has been designed to grade the micro‐coking panels through colour recognition. This not only allows visual grading to be faithfully reproduced but also eliminates the subjective element of colour grading. The results obtained with the ‘Video‐Rater’ constitute a first step towards computer‐assisted gradi

ISSN:1354-4063    

DOI:10.1002/tt.3020040205

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractThe abrasive wear properties of materials in sliding contact with solid mineral particles during the comminution process have been studied. The equipment used can simulate the tribo‐conditions inside coal pulverisers. Using this experimental apparatus, a number of different cemented tungsten carbides have been tested and classified according to their resistance to abrasive wear in rubbing contact with particulate coal. The paper shows that the wear results can be used to estimate the resistance of a material to brittle fragmentation and chipping of the edges during tribo‐contact with solid particles. An equation is presented which enables calculation of the fracture resistance factor, KWR, based on results from carefully controlled repeated abrasion te

ISSN:1354-4063    

DOI:10.1002/tt.3020040206

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractDuring sheet‐metal forming processes, the friction conditions have a decisive influence on forming limits, the robustness of the production process, and the quality of the parts produced, with significant forces required to overcome friction between the sheet and the tools. If batch‐to‐batch reproducibility is to be guaranteed, an appropriate method of characterising the sheet surface topography is needed to monitor the sheetmetal fabrication process. Newly developed optical measurement techniques and computer workstation technology are presented, which enable the topography of sheet surfaces to be described in three dimensions. New parameters for describing sheet surface topography are developed. This may correlate more closely with frictional behaviour in sheet stamping than the previously used two‐dimensional parameters, with the size, shape, and distribution of the peaks and valleys of the topography defined. Results generated on a special drawing friction test machine indicate that numerous narrow peaks and large, separate, uniformly distributed valleys yield a desirable resistance to a

ISSN:1354-4063    

DOI:10.1002/tt.3020040207

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractThe hardness, adhesion, and tribological behaviour of magnetron‐deposited coatings (TiN and (Ti,Al)N) have been determined and related to microstructure composition. To enhance the adhesion of the coating, plasma nitriding of substrates was employed. Wear behaviour, coefficient of friction and contact temperature were measured using computerised data acquisition and processing. The bonding force between the coated samples and counter material was monitored and controlled by newly designed and constructed equipment, to keep a constant level of load during sliding. With the new hardware and software, it was possible to monitor on‐line the development of the wear process. The hardware consisted of PC computer, piezoelectric transducer, sensors with high sensitivity, microprocessor‐controlled measuring system, AD/DA transformer, and multichannel plotter. The wear zone morphology and characteristics of the surface layer structure and other important properties were investigated using scanning electron microscopy (SEM) and X‐ray diffraction analysis (XRD). Energy dispersive X‐ray analysis (EDAX) of the wear scars on pins provided essential information on the wear characteristics. Based on the results, the correlations between the mechanical properties, the surface structure, and tribological characteristics are

ISSN:1354-4063    

DOI:10.1002/tt.3020040208

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractA Time Dependent Particle Quantifier (TDPQ) system can measure the concentration of ferrous wear debris suspended in a lubricant, and the severity of wear associated with the particle size of this suspended debris. A coding system is proposed covering: PQ index (total wear); initial TDPQ slope (large particles); and final TDPQ slope (small particles). Correlation with existing measurement systems is also given.

ISSN:1354-4063    

DOI:10.1002/tt.3020040209

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020040210

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020040211

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY