摘要:

A technique has been developed to form friction-reducing and antiwear films in-situ by means of an electric field applied between rubbing metal surfaces. Using this in-situ charging technique, the effectiveness of zinc organodithiophosphate (ZDP) additives as antiwear and friction reducing agents can be enhanced by electrochemical reactions which form surface coatings. The coatings formed on sliding surfaces compared with uncharged surfaces reduce friction by up to 35 percent. In addition, during the sliding process, the films formed on the surfaces are replenished and protect the rubbing surfaces from wear. A steel plate subjected to rubbing and in-situ charging for four hours had a smooth surface and a yellowish reaction film; the one without charging was rougher and no yellowish reaction film was formed. The improved tribological characteristics are attributed to an increase in the electrochemical reactivity of the ZDP-mineral oil blends and the formation of phosphate or sulfate films on the metal surfaces.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982060

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In this paper a novel, high load squeeze film damper design, supporting analysis, and experimental results are presented. The spiral foil multi-squeeze film damper demonstrated that two to four fold or larger increases in damping levels are possible without resorting to significantly decreased damper clearances. As a result, the nonlinearities associated with high eccentricity operation are avoided. Controlled orbit tests with a dual squeeze film configuration were completed and favorably compared with theoretical predictions. The ability to accommodate high steady state and transient imbalance conditions make this damper well suited to a wide range of rotating machinery, including aircraft gas turbine engines.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982061

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The friction and wear of a 20 via silicon carbide whisker-silicon nitride matrix composite was measured at room temperature in both lubricated and unlubricated sliding. A pin-on-disk test configuration was used in which the pin member was a 9.53 mm diameter sphere. Silicon carbide and silicon nitride spheres were tested against the composite in both unidirectional and reciprocating sliding. The range of experimental parameters included normal forces from 1 to 45 N, velocities of 0.1 and 0.3 m/s and test durations of five minutes to three hours. The lubricant used in the room temperature tests was a commercial synthetic, fully formulated engine oil (5W30). In unlubricated sliding, silicon nitride produced more severe wear of the composite than did silicon carbide. In lubricated sliding, very little wear occurs in either sliding pair at even the longest test exposure. The data are presented in “wear space” co-ordinates and this form of presentation is compared to other wear mechanism map concepts presently in use.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982062

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The problem of hydrodynamic lubrication under conditions of suddenly applied loads is of practical importance and theoretical interest. For example, such conditions may occur if a turbine blade fractures. From a theoretical point of view, the classical theory of Reynolds, which is quasi-steady, may not be applicable. Reynolds' equation does not depend on bearing surface accelerations, which may be considerable, but only on bearing surfaces1 velocities.

ISSN:1040-2004    

DOI:10.1080/10402009108982063

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper deals with the sealing characteristics of mechanical face seals from the viewpoint of rubbing surface conditions. The relationship between topography of the sealing surface of the mechanical face seal and the frictional, wear and sealing characteristics were experimentally evaluated.

ISSN:1040-2004    

DOI:10.1080/10402009108982064

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Friction coefficients of less than 0.02 and negligible wear have been attained and continuously maintained in a pin-on-disc apparatus between a sapphire pin and discs of Sialon, silicon carbide, zirconia or zirconialalumina as long as a carbonaceous gas or vapor, such as ethylene, propane, benzene, or 1-propanol, was supplied to the conjunction region. Mean contact pressures were around 300 MPa and bulk temperatures were varied between ambient and 700°C. For every ceramic and vapor combination some temperature ranges exhibited high friction and wear, others very low friction and wear. Raman and Auger spectroscopies of the carbonaceous deposits formed in the wear tracks show significant differences depending on the temperature range and the feed gases or vapors supplied. In general, friction and wear reduction occurred in two steps at different rates. The tribochemistry involved is likely to comprise hydrocarbon acid-catalytic cracking at low temperatures and pyrolysis at high temperatures.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982065

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper contains the results of comparisons between the effects of three different lubrication methods, flooded, directed and leading-edge, on the performance of a tilting-pad journal bearing. Experimental pad temperatures and power loss data are presented for a 127 mm diameter, four pad bearing, operating over a range of shaft speeds up to 7000 rpm (46.6 m/s) and loads up to 22 kN (1.3 MPa). The experimental data indicate that temperature and power loss reductions are attainable with the use of the different lubrication methods. However, these are not as significant as those achieved with their use in tilting-pad thrust bearings.

ISSN:1040-2004    

DOI:10.1080/10402009108982066

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The effect of journal eccentricity on the static and dynamic performance of a water lubricated, five-recess hybrid bearing is presented. The hydrostatic bearing has been designed to operate at a high speed and with a large level of external pressurization. The operating conditions determine the flow in the bearing to be highly turbulent and strongly dominated by fluid inertia effects. The analysis covers the range of journal center displacements directed toward the middle of a recess and toward the mid-land portion between two consecutive recesses. Predicted dynamic force coefficients are constant for small to moderate eccentricities. For large eccentricities, fluid cavitation and recess position determine large changes in the bearing dynamic performance. The effect of fluid inertia force coefficients on the threshold speed of instability and whirl frequency ratio of a single mass flexible rotor is discussed.

ISSN:1040-2004    

DOI:10.1080/10402009108982067

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper models the transverse “runout” of a flexible, nonflat, spinning disk. Analysis is provided to compute the deflection that a warped or skewed disk will take after spinning. This is a problem of importance in magnetic and optical recording, for which spacing and/or contact with the recording head must be precisely controlled. The effect of disk nonflatness appears as an equivalent pressure load in an analogous formulation for a flat plate. Results are presented for various freely spinning disks. Comparisons to experiments show the range of the models predictive capability.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982068

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This study examines the wear resistance of Si3N4-TiC composites subjected to pin-on-diamond disk abrasion and gas-jet Al2O3-particle erosion. The contact damage and wear resistance have been related to the mechanical properties and microstructure of the composites, which differ by their volume fraction and grain size of TiC particulates. Findings suggest that predictions of ceramic composite wear resistance based solely upon hardness and fracture toughness, in the absence of additional information regarding microstructure, may be inaccurate. Wear resistance of Si3N4-TiC composites was found to be more reliably defined by including dispersoid separation, a function of its size and volume fraction, into predictive equations.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982069

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor