摘要:

Steels containing up to 12 percent of chromium have been used in unlubricated pin-and-disk continuous sliding wear experiments. Variations in wear rates with load followed the pattern already reported for carbon steels, namely, a transition from severe to mild wear at a particular transition load. Chromium contents greater than three percent have a strong and unexpected influence upon the wear rates at loads above the transition load. The variations of the friction coefficients with increasing load tended to decrease in a continuous fashion for chromium contents less than three percent. Above this percentage, however, the friction showed a transition at the same load as for the wear rate transitions. It is shown that the wear transitions are probably due to changes of phase in the surface structure from that of the rhombohedral oxide to that of the spinel oxide as the load is increased. The proportionate amounts of spinel and rhombohedral oxide in the wear debris after the transition load has been exceeded is shown to be strongly connected with the wear rate. Comparison with static oxidation results reveals that the transition from mild to severe wear probably occurs at a contact temperature of about 300 C. Finally, it is shown that the decrease in wear rate with increasing chromium content is compatible with an increase in the activation energy needed for oxidation to occur at the real area of contact between the sliding surfaces.Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE International Lubrication Conference held in New York City, October 9–12, 1972

ISSN:0569-8197    

DOI:10.1080/05698197308982728

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A new type of disc machine has been developed which may be used for evaluation of the load-carrying properties of lubricants. Commissioning tests revealed that it possesses some advantages over more conventional machines, notably in terms of operating range and flexibility. Examination of critical temperature and film thickness failure criteria suggested that both approaches may be used to explain the occurrence of lubricant film breakdown. The machine has shown its ability to differentiate between oils of different load-carrying properties, and encouraging agreement with the IAE gear machine, when operated under similar conditions, has been obtained.Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE International Lubrication Conference held in New York city, October 9–12, 1972

ISSN:0569-8197    

DOI:10.1080/05698197308982729

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

This paper deals with optimization of the contact geometry of hydrodynamic lip seals with beams moulded on the air side. Seals for both unidirectional and bidirectional rotation are studied.

ISSN:0569-8197    

DOI:10.1080/05698197308982730

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Using the Bowden-Leben apparatus, the effects of load and surface roughness on the frictional behavior of various steels are studied over a range of temperature and of additive concentration. Cetyl amine and long-chain acids were used as surfactants, cetane and squalane being the carriers.

ISSN:0569-8197    

DOI:10.1080/05698197308982731

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Analyses are presented for compressible fluid flow across shaft face seals with face deformation. The solutions are obtained from an approximate integral analysis. The models, used in this analysis, can predict gas film seal behavior operating at subsonic or choked flow conditions. The flow regime can either be laminar or turbulent. Entrance losses can also be accounted for. When fluid inertia effects are negligible (quasi fully developed flow) and the sealing faces are slightly deformed, the following results are found for both laminar and turbulent flows: (a) the pressure profiles are independent of fluid properties; and (b) the parallel film leakage equation can be used, provided a characteristic film thickness is used. However, fluid inertia effects were found to be very important for near-choked and choked flow conditions. For these conditions the pressure profiles are dependent upon the fluid properties. Pressure profiles are presented for both divergent and convergent seal faces under choked flow conditions.Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972

ISSN:0569-8197    

DOI:10.1080/05698197308982732

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

It is suggested that fluid film thickness in a starved EHD contact is determined by the rate at which lubricant is forced from the Hertz zone normal to the rolling direction. A simple model allows calculation of this flow rate, together with related quantities of interest to the designer.Presented at the 27th ASLE Annual Meeting in Houston, Texas, May 1–4, 1972

ISSN:0569-8197    

DOI:10.1080/05698197308982733

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The effects of fluids on O-rings of various elastomers have been determined under test conditions involving simultaneous exposure to the fluid and air. This is in contrast to conventional methods of testing which involve total immersion in a single medium, e.g., all air or all fluid. Performance has been assessed on the basis of compression set resistance, retention of sealing force as measured by stress relaxation, as well as other physical property measurements.

ISSN:0569-8197    

DOI:10.1080/05698197308982734

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Damage scar volume measurements taken from like metal fretting pairs, combined with scanning electron microscopy observations, showed that three sequentially operating mechanisms result in the fretting of titanium, Monel-400, and cobalt–25 percent molybdenum. Initially, adhesion and plastic deformation on the surface played an important role. This was followed after a few hundred cycles by a fatigue mechanism, producing spall-like pits in the damage scar. Finally, an oxidation related mechanism became most significant. Damage scar measurements made on several elemental metals after 6 × 105fretting cycles suggested that the ratio of oxide hardness to metal hardness was a measure of the susceptibility of a metal to progressive damage by fretting.Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973

ISSN:0569-8197    

DOI:10.1080/05698197308982735

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Dialkyl acid phosphates are effective antiwear agents in neopentyl polyol ester lubricants applied to 440C stainless steel sliding surfaces at low loads, but they promote ester deterioration. Various amine salts of three representative dialkyl phosphates were studied to determine if the adverse effect could be reduced without sacrificing antiwear properties. The amine phosphates were generally highly effective in the low load region in four-ball wear tests. They were at least as effective as the parent acid phosphates and appreciably more effective than tricresyl phosphate. Little effect of amine structure on performance was observed. At a higher load, both the acid phosphates and their amine salts had no beneficial effect on wear. The amine phosphates promoted significantly less deterioration of the base ester under four-ball test conditions (266F) than did the dialkyl phosphates. In oxidation-corrosion tests at 3253, however, they were corrosive to copper and adversely affected ester stability.Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973

ISSN:0569-8197    

DOI:10.1080/05698197308982736

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

An experimental gas-bearing test program was initiated to establish the answer to two specific questions. Is present-day gas bearing technology accurate enough to predict actual bearing performance under typical jet engine operating conditions? And, are gas journal and thrust bearings capable of carrying the required high operating loads that can be imposed by the engine when maneuvering at high. altitudes, which are considered the most severe bearing operating conditions? A bearing element component rest rig was built to simulate jet engine conditions. Tests were performed and the results, reported herein, indicate positive answers lo the above questions.Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973

ISSN:0569-8197    

DOI:10.1080/05698197308982737

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor