摘要:

AbstractThe tribological properties of various PVD‐deposited coatings (vacuum arc method) have been tested, both single‐layer coatings (TiN, CrN, Ti(C,N), and Cr(C,N)) and multilayer coatings (Cr(C,N)/CrN/Cr and CR(C,N)/(CrN+Cr2N)/CrN/Cr). An unlubricated ball‐on‐disc tribosystem was used in which an Al2O3ball is pressed against a coated steel disc rotating in the horizontal plane. A novelty of the method is the removal of wear debris from the contact zone using a draught of dry argon. This improves the repeatability of the test results and the stability of the tribological characteristics.It is shown that CrN coatings exhibit the best antiwear properties and Ti(C,N) the worst. Multilayer coatings have better antiwear properties than single‐layer ones. The friction coefficients for CrN and Cr(C,N) coatings are much smaller than for the commonly used TiN.A correlation has also been found between the physical properties of the coatings tested (adhesion of the coating to the substrate assessed in scratch tests, and coating hardness) and their antiwear properties. An improvement in coating‐substrate adhesion results in wear reduction, while greater hardness (causing a coating embrittlement increase and a change in the wear mechanism) brings about greater wear. There is no correlation between the physical properties and the friction coefficients of the coat

ISSN:1354-4063    

DOI:10.1002/tt.3020100102

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractIn order to characterise materials for tribological applications, model tests with simple contact geometry are in widespread use. Friction and wear behaviour can be determined with high accuracy from this type of test. Tests with oscillating sliding motion have the advantage that only small‐sized specimens are required. However, the fact that the results of model tests are affected considerably by the choice of test parameters is often overlooked. In order to check the influence of test parameters on friction and wear results, tests were performed in which the relevant parameters (stroke, frequency, load, relative humidity of the surrounding air) were varied. Comparative studies with different SiC‐based materials (SiC, SiSiC, and SiC‐TiC) against steel (100Cr6) under unlubricated conditions at room temperature show that in all cases the relative humidity is an important parameter, influencing the friction and wear results substantially. Additionally, several parameters can modify friction and wear behaviour more or less significantly. The effects of test parameters on friction and wear are discussed here on the basis of the wear mechanism. Some of the consequences of this for planning test series and for the practical use of test results are

ISSN:1354-4063    

DOI:10.1002/tt.3020100103

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractAlthough the performance and reliability of pneumatic cylinders depend to a great extent on the friction generated at the seals, the friction characteristics have not been widely studied. Both the literature and manufacturers' catalogues rarely discuss the friction characteristics of pneumatic cylinders, and the lack of friction models limits the design, optimisation, and analysis of pneumatic cylinder systems. In seeking to improve the characteristics of pneumatic cylinders and to clarify the friction phenomenon, this paper describes friction force measurement tests carried out in pneumatic cylinders of six different diameters, from 32 to 100 mm. An experimental apparatus was designed to assess the effect of a broad range of operating conditions, where the velocity and pressure of the cylinder chambers are controlled independently. Measurements of friction force are shown for velocities of up to 0.5 m/s and pressures of up to 0.8 MPa. The data obtained will be useful for developing a suitable friction model, and the experimental apparatus will allow study of the effects on the friction force of different types of seal, lubricant, and cylinder barrel.

ISSN:1354-4063    

DOI:10.1002/tt.3020100104

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractThe mechanism of ploughing wear of martensite nodular cast iron has been investigated by means of elastic contact theory, stress interferometry, and scanning electron microscopy. Stress distributions in the contact area are plotted through numerical quadrature. The results show that the formation of cracks is between 0.2a and 0.5a (a is the radius of the contact curve). The driving force to produce crack extension along the Y axis is τyzmaxand the extension direction is 45° to the horizontal. The driving force to produce crack extension along the X axis is either τxor τxzmaxand the direction of crack extension is 37° to the horizo

ISSN:1354-4063    

DOI:10.1002/tt.3020100105

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractA series of cooperative interlaboratory tests (‘round robins’) was conducted in 1997, 1998, 1999, 2000, and 2001 by the DIN 51834 Working Group on Tribological Tests in Translatory Oscillation Apparatus. Statistical analysis of these results showed the influence of cleaning solvent, machine model, and evaluation criteria on the tribological properties of the lubricants tested. Coefficients of friction and wear results were ranked according to the effects of ten different cleaning solvents, where isopropanol gave the lowest values and isoparaffin solvents the highest. The effect of machine model on coefficients of friction varied from about 0.2 to 0.9% of the average. Wear results were not affected. The tests also showed that the seizure criteria and methods of measuring wear required in the test procedure do not provide a suitable measure of the tribological properties of certain lubrica

ISSN:1354-4063    

DOI:10.1002/tt.3020100106

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020100107

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020100108

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020100101

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY