摘要:

Infrared microscopy (μ-FTIR), Raman spectroscopy, Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize bearing surfaces lubricated from the vapor phase. Results are presented for surface films generated with a tertiary-butyl phenyl phosphate (TBPP) and a polyphenylether (5P4E). Infrared bands consistent with inorganic poly-phosphates and phosphites were detected in deposition films generated with the TBPP lubricant. Raman shifts consistent with graphite of short range order were detected in films deposited by both lubricants. However, specimens lubricated by the 5P4E had several Raman shifts consistent with Fe2O3and Fe3O4. Iron oxides were not detected in deposition films generated with the TBPP lubricant. AES depth profiles indicate a predominant mixture of iron and carbon in the TBPP deposition film; whereas, the 5P4E film predominately consists of iron and oxygen. Localized corrosion pitting generated with the TBPP lubricant was analyzed using AES, SEM, and EDS. The results indicate that a modified matrix rich in phosphorus, oxygen and carbon, with a corresponding depletion of iron, transcends to depths of at least 10 microns in the substrate in damaged regions. Lubrication and failure mechanisms of vapor lubricated bearings are proposed based on the results.Presented at the 51st Annual Meeting in Cincinnati, Ohio May 19–23, 1996

ISSN:1040-2004    

DOI:10.1080/10402009908982183

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Auger depth profile data, obtained from vapor-lubricated T15 bearing steel, were modeled using the solution for diffusion in a semi-infinite pair. A tertiary-butyl phenyl phosphate was used as the vapor lubricant. The primary species undergoing diffusion are iron and carbon. The objective of the experiment was to determine the order of magnitude of the diffusion coefficient and to qualitatively assess what types of diffusion mechanisms are involved. The experimental results indicate that the diffusion profile travels at a velocity equal to the bearing wear rate under dynamic conditions. This is possible if iron diffusions at a faster rate than carbon, i.e., the Kirkendall effect. Analyses of the data were performed using Darken's equations. The results indicate that the diffusion coefficient of iron is of the order of 1 × 10−14cm2/s at test temperatures of 370° and 430°C. Diffusion is thought to occur via the migration of iron cations through an anionic lattice of polyphosphate and phosphite, i.e., cation diffusion. The diffusion mechanism provides a satisfactory explanation of how several hundred monolayers containing iron can exist in vapor deposition film grown from organophosphorus lubricants. The chemical gradient, ionic attraction, and the extreme stress gradients of the Hertzian contact are thought to contribute to diffusion under dynamic conditions.Presented at the 53rd Annual Meeting in Detroit, Michigan May 17–21, 1998

ISSN:1040-2004    

DOI:10.1080/10402009908982184

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The tribological behavior of self-mated ceramic composites, like SiC-TiC, Si3N4-TiN and (Ti, Mo) (C, N)+Ni, were characterized under dry-sliding friction. The coefficient of friction still remains unchanged on a level known from SiC and Si3N4ceramics. The addition of titanium compounds to SiC and Si3N4ceramics reduced the wear rate compared to titanium-free ceramics. Increasing sliding speed and temperature enhances this trend. The (Ti, Mo) (C, N) materials exhibited a wear behavior nearly independent from sliding speed and temperature with wear rates lower than 10−7mm3/Nm up to 800°C. The present study utilized small-spot X-ray diffraction, laser raman spectroscopy (LRS) and transmission electron microscopy (TEM) TiO2and TinO2n·1,-type crystalline Magneli-phases with a crystallographic shear structure as well as some double oxides like NiTiO3, Mo0.975Ti0.025O2and β-NiMoO4, were detected on different ceramic substrates formed by tribo-oxidation during tests at 400°C and 800°C. The conditions during tribological operation are sufficient to generate crystalline Magneli-phases by tribo-oxidation, like γ -Ti3O5, Ti5O9and Ti9O17.

ISSN:1040-2004    

DOI:10.1080/10402009908982185

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Polymer-coated steels are of interest in the production of food and beverage containers because of their potential utility as solid lubricants and because of the potential elimination of a post-forming polymer spray operation which is time consuming and produces environmentally hazardous emissions. Unfortunately, little work has been done regarding formability of polymer-laminated steels in metal-forming operations, and this is especially true of the ironing process. This paper presents an experimental and theoretical investigation into the ironing formability of polymer coated steels. A strip ironing simulator is used to perform ironing tests at a large number of tooling geometries and thickness reductions. From the experiments, it is found that polymer coated steels will either iron successfully or will be shaved off of the substrate, and that the active mechanism depends most strongly on the die angle. An upper bound model is developed which predicts the circumstances under which successful ironing and shaving will occur and is supported by the experiments. This model allows base-stock providers to design better coatings for improved formability of polymer-coated steels.Presented at the 53rd Annual Meeting in Detroit, Michigan May 17–21, 1998

ISSN:1040-2004    

DOI:10.1080/10402009908982186

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The paper describes a simplified non-Newtonian numerical model of an elastohydrodynamic point contact. It is based on the control volume flow continuity technique described by Holt et al. (9). Observation of the shear stress values produced in the solutions to the problem obtained by Holt has led to the consideration of a simplifying approximation in the non-Newtonian formulation for calculation of flow rates in which the resultant shear stress is approximated by the shear stress in the predominant direction of sliding. This assumption gives easily calculated expressions for the flow rates. The simplification leads to direct evaluations of the surface shear stress components without recourse to an iterative solution of simultaneous transcendental equations. Results of the simplified model are found to agree with the more exact treatment of Holt et al, under realistic operating conditions. A thermal treatment of the oil film for sliding contacts is also included. Experimental measurements of film thickness in contacts with varying degrees of sliding have been carried out which show good agreement with the simplified theory.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998

ISSN:1040-2004    

DOI:10.1080/10402009908982187

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Mechanical seals are a vital component of rotating equipment in the process and power generation industries. Due to the mechanical seal's wide range of application, mechanical seal failures constitute a large proportion of the overall mechanical failures resulting in unscheduled machinery shutdown and even catastrophic consequences.

ISSN:1040-2004    

DOI:10.1080/10402009908982188

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A formulation of a non-steady problem for elastohydrodynamically lubricated (EHL) non-conformal contact is considered. It takes into account elasticity of contact bodies, lubricant viscosity and changing in time location of the inlet boundary, velocities of the contact surfaces and applied load. The main goal of this paper is to propose a “modified” formulation of the problem free of certain defects. A “traditional” and “modified” formulations of the problem, leading to discontinuous and smooth solutions in cases of abrupt changes in external load applied to a contact and linear velocities of its surfaces, are considered. For the case of purely squeezed lubrication film, an analytical and numerical analysis of the dynamic response of a lubricated contact to abrupt changes in external load is performed. It is shown that in the case of purely squeezed rigid surfaces it takes infinite time to bring the surfaces in direct contact, i.e. theoretically, the film thickness never reaches zero.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 26–28, 1998

ISSN:1040-2004    

DOI:10.1080/10402009908982189

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The load capacity of a plain journal bearing is calculated using newly derived analytical models for the density and the viscosity of aerated oil. The results show that oil aeration can double the load capacity of plain journal bearings. This is due to a doubling of the effective oil viscosity caused by the surface tension of the entrained air bubbles. The compressibility of the aerated oil is found to have little effect on load capacity. Physical explanations of these results are offered.

ISSN:1040-2004    

DOI:10.1080/10402009908982190

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The standardized FZG apparatus is widely applied for assessing the anti-scuffing properties of gear lubricants. However, this test is very time-consuming and expensive. For the development of new transmission lubricants, quicker and less expensive tests would be useful. In this two-part article, the possibility to qualify gear lubricants by means of two common bench tests (SRV Optimol and four-ball) was investigated. In the first part, the different test rigs (FZG, SRV, four-ball) are presented and the parameters related to scuffing according to literature (lubricant film thickness, flash temperature and contact pressure) are calculated for the three testers. In the second part, test results of eight lubricants obtained with the three test rigs are presented and compared. Results showed a.o. that the SRV wear scar diameter and the four-ball load-wear index correlated with the FZG failure load stage. Inconsistencies between test results are clarified based on lubricant composition and the parameters related to scuffing calculated in the first part. The relevance of the different scuffing criteria is discussed. Finally, quicker and less expensive, but reliable test procedures than FZG are presented to determine the resistance to scuffing of gear lubricants.

ISSN:1040-2004    

DOI:10.1080/10402009908982191

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The standardized FZG apparatus is widely applied for assessing the anti-scuffing properties of gear lubricants. However, this rest is very time-consuming and expensive. For the development of new transmission lubricants, quicker and less expensive tests would be useful. In this two-part article, the possibility to qualify gear lubricants by means of two common bench tests (SRV Optimol and four-ball) was investigated. In the first part, the different test rigs (FZG, SRV, four-ball) are presented and the parameters related to scuffing according to literature (lubricant film thickness, flash temperature and contact pressure) are calculated for the three testers. In this part, test results of eight lubricants obtained with the three test rigs are presented and compared. Results showed a.o. that the SRV wear scar diameter and the four-ball load-wear index correlated with the FZG failure load stage. Inconsistencies between test results are clarified based on lubricant composition and the parameters related to scuffing as calculated in the first part. The relevance of the different scuffing criteria is discussed. Finally, test procedures that are quicker and less expensive than FZG but still reliable for determining the resistance to scuffing of gear lubricants are presented.

ISSN:1040-2004    

DOI:10.1080/10402009908982192

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor