摘要:

This study was carried out to see if solid-lubricant films on metal surfaces wear monotonically, or if there is occasional migration from a region on the wear track with copious lubricant to one from which the lubricant has been worn away. To facilitate this study, a new pin-on-disk apparatus was constructed with the capability of continuously measuring the friction and the exoelectron emission from tile wear track. Sliding tests were carried out using a circular wear track which, initially, traversed a path partly on an unlubricated surface and partly on a surface covered by a solid-lubricant film. It was found that lubricant films of rubbed graphite and molybdenum disulfide showed no spreading of the lubricant along the wear track, but polytetrafluoroethylene had some capability for migration and, hence, healing of a denuded wear track.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982

ISSN:0569-8197    

DOI:10.1080/05698198308981487

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Hydraulic control valves in commercial aircraft are subject to “erosion” in service with phosphate eśter fluids, due to corrosion from generation of electrokinetic streaming currents. This “zeta corrosion” phenomenon is now well understood. The theory is extended here to calculate current densities that would be generated on the surfaces of lubricated journal bearings and roller bearings. Measurements of such current densities made with a disk electrode in a simulated journal bearing are in approximate agreement with the model. Many aspects of bearing wear reported in the literature are consistent with the zeta corrosion mechanism.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982

ISSN:0569-8197    

DOI:10.1080/05698198308981488

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

An analytical study of the dynamics of a piston in a reciprocating engine was conducted. The analysis, which incorporates a hydrodynamic lubrication model, was applied to a V-8 automotive spark ignition engine. The variation of piston transverse position and rotation with crank angle, and the piston-skirt frictional power loss were calculated for different wrist pin locations, piston-to-cylinder clearances, and lubricant viscosities. The results obtained indicate that piston motion is strongly affected by the location of the wrist pin and that piston-skirt friction is increased significantly if the wrist pin is at an unfavorable position. In addition, piston dynamics were found to be sensitive to piston-cylinder bore clearance and lubricant viscosity, underscoring their importance in engine design.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982

ISSN:0569-8197    

DOI:10.1080/05698198308981489

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Solid particle erosion of an austenitic stainless steel was studied utilizing various metallographic techniques. Examination of single impacts on a polished surface resulted in a semiquantitative crater classification. It was, however, found that material removal generally involves the interactive effect of several cumulative impacts. Consequently, topography and internal structure of the target surface layer after multiple impacts were investigated. In particular, preeroded targets were reexamined after additional single impacts. The strength of the surface layer was estimated by a simple tape experiment, which also supplied information of the size and morphology of presumptive wear debris. Two major erosion mechanisms were distinguished:1.Cutting erosion. Detachment of crater lips by cutting action of one or several impacts.2.Deformation erosion. Detachment of material by surface fragmentation due to multiple cumulative impacts.

ISSN:0569-8197    

DOI:10.1080/05698198308981490

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The wear behavior of two lubricant base stocks, a pentaerythrityl ester and a synthetic hydrocarbon, was investigated with the Four-Ball machine. Wear volumes of the stationary balls were evaluated from the wear scar diameter and by surface profilometry. Surface profilometry was also used to determine wear volumes for the rotating ball.

ISSN:0569-8197    

DOI:10.1080/05698198308981491

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A boundary lubrication study was made to compare five recently developed C-ether-formulated fluids with an advanced formulated MIL-L-27502 candidate ester. Steady-state wear and friction measurements were made with a sliding pin-on-disk friction apparatus. Conditions included disk temperatures up to 260°C, dry-air test atmosphere, 1-kilogram load, 50-rpm disk speed, and test times to 130 minutes. Based on wear rates and coefficients of friction, three of the C-ether formulations as well as the C-ether base fluid gave better boundary lubrication than the ester fluid under all test conditions. The susceptibility of C-ethers to selective additive treatment (phosphinic esters or acids and other antiwear additives) was demonstrated when two of the formulations gave somewhat improved lubrication over the base fluid. Also, the increased operating potential for this fluid was shown in relationship to bulk oil temperature for MIL-L-23699 and MIL-L-27502 type esters.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982

ISSN:0569-8197    

DOI:10.1080/05698198308981492

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Modern engine oil formulations usually contain many kinds of additives, such as detergent-dispersants, antioxidants, VI improvers, rust inhibitors, and friction modifiers. However, what these additives do in the crankcase is not yet fully understood. As a first step in clarifying the complex mechanisms of engine oil performance in the crankcase, the interaction of engine oil additives was studied on the basis of surface chemistry.

ISSN:0569-8197    

DOI:10.1080/05698198308981493

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The results presented in this paper demonstrate that the process of intercalation; i.e., the formation of chemical compounds via insertion of atomic or molecular species in the van der Waals gap between planes of lamellar solids can substantially improve the intrinsic lubricating properties of solids. Using graphite as a model host compound, various transition metals and metal chlorides intercalated into graphite were formulated into solid film lubricants and their lubricating properties determined in a laboratory wear test device. Comparisons of endurance life and load-carrying capacity are made relative to molybdenum disulfide and unintercalated graphite. Graphite/19.8 wt. percent CoCl2was found to exhibit over a fivefold increase in endurance life while graphite/19.3 wt. percent NiCl2provided a greater than twofold increase in load-carrying capacity relative to graphite and was equivalent to MoS2. The degree of improvement in endurance life was found to be dependent on the concentration of intercalant in graphite and the resulting increase in interlayer carbon spacing due to intercalation. A total of 23 different intercalate compounds were investigated at various concentration levels.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982

ISSN:0569-8197    

DOI:10.1080/05698198308981494

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A Latin-square statistical experimental test design was used to evaluate the effect of temperature, load, and sliding speed on the tribological properties of graphite fiber reinforced polyimide (GFRPI) composite specimens. Hemispherically tipped composite riders were slid against 440C HT stainless steel disks. Comparisons were made to previous studies in which hemispherically tipped 400C HT stainless steel riders were slid against GFRPI composite disks and to studies in which GFRPI was used as a liner in plain spherical bearings. The results indicate that sliding surface geometry is especially important, in that different geometrics can give completely different friction and wear results. Load, temperature, and sliding distance were found to influence the friction and wear results but sliding speed was found to have little effect. Experiments on GFRPI riders with 10 weight percent additions of graphite fluoride showed that this addition had no effect on friction and wear.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1992

ISSN:0569-8197    

DOI:10.1080/05698198308981495

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

This paper examines the effects of damped vibrational frequencies on the linear reduced dynamical stiffness and damping coefficients of tilting-pad journal bearings. The frequency ratio (damped frequency/running speed) can be used to judge the accuracy of employing synchronously reduced linear coefficients in rotordynamic stability analyses. The use of these coefficients can result in simpler formulations of the system dynamical equations of motion and solution techniques as well as reduced computational and analysis time. Results presented here indicate that synchronously reduced bearing dynamical coefficients are generally adequate for stability analyses with positively preloaded tilting-pad bearings. Plots of dynamic coefficients are included for a five-pad bearing.Presented at the 37th Annual Meeting in Cincinnati, Ohio, May 10–13, 1982

ISSN:0569-8197    

DOI:10.1080/05698198308981496

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor