摘要:

The advantages and disadvantages of elemental silver as a tribological material are discussed. The relatively high melting point of 961°C, softness, marked plasticity, and thermochemical stability of silver combine to make this metal useful in thin film solid-lubricant coatings over a wide temperature range. Disadvantages of silver during sliding, except when used as a thin film, are shown to be gross plowing due to plastic deformation under load with associated high friction and excessive transfer to counterface surfaces. This transfer generates an irregular surface topography with consequent undesirable changes in bearing clearance distribution. This paper describes research to overcome these disadvantages of elemental silver. A comparison is made of the tribological behavior of pure silver with that of silver formulated with other metals and high-temperature solid lubricants. The composite materials are prepared by codepositing the powdered components with an airbrush followed by furnace heat treatment or by plasma-spraying. Composite coatings were formulated which are shown to the self-lubricating over repeated temperature cycles from low temperature to about 900°C.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

ISSN:0569-8197    

DOI:10.1080/05698198608981698

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The oxidative breakdown of lubricating oils is accompanied by the liberation of vapor-phase oxidation products. A simple apparatus which uses a semiconducting tin oxide gas sensor has been employed to monitor the evolution of these products and determine the length of the induction period.

ISSN:0569-8197    

DOI:10.1080/05698198608981699

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The complete nonlinear equations of motion of a flexibly mounted stator in a noncontacting coned-face mechanical seal are solved numerically. The solution utilizes a transient dynamic analysis and takes into account rotor axial runout and assembly tolerances in the form of initial stator misalignment. Cavitation of the fluid film is also accounted for. A parametric investigation is performed and the effect of various design parameters and operation conditions on the seal dynamics is presented and discussed. A critical shaft speed is found above which the seal becomes dynamically unstable. A critical rotor runout is found which, if exceeded, will cause seal failure due to local face rubbing contact. A comparison is made between the numerical results and those of a simpler analytical solution. It is found that the analytical solution is valid for most practical applications of mechanical seals.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

ISSN:0569-8197    

DOI:10.1080/05698198608981700

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Data processing techniques have been developed for the manipulation and enhancement of spectroscopic data. They have been applied to the infrared spectra of degraded base oils and lubricants to provide information on oxidation processes and additive depletion. Samples have been acquired from oils that have been subjected to laboratory scale oxidation and from lubricants during standard engine tests. Results are evaluated in terms of chemical species that are lost and formed during oxidative degradation.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

ISSN:0569-8197    

DOI:10.1080/05698198608981701

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Some computer tapes exhibit excessive friction after repeated use or through use in some tape drives. An objective of this study was to develop methodology for monitoring the physical and bulk-chemical changes of tapes during wear and correlating any changes with increases in friction. From simulated head-tape interface tests and tape-drive tests, we have generally observed an increase in friction during tape wear. Bulk-chemical properties were monitored and did not change during wear. Changes in surface smoothness were not found significant enough to account for the increase in friction, but a noticeable increase in the real area of contact was measured and indicated mechanical and/or chemical changes in the tape surface. Techniques for monitoring surface chemistry need to be developed before specific changes in tape surface that lead to an increase in friction can be fully understood.

ISSN:0569-8197    

DOI:10.1080/05698198608981702

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The dynamic behavior of flexible rotors supported on fluid-film bearings are studied including the rotational stiffness and damping coefficients of the oil film. The rotational stiffness and damping coefficients have been evaluated for a finite cylindrical fluid-film bearing by solving the appropriate Reynolds equation for the oil film, using finite difference method. The resulting critical speeds and the unbalance response for a single-disk flexible-rotor system modelled by finite element method are compared with those which were obtained using a short bearing approximation.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

ISSN:0569-8197    

DOI:10.1080/05698198608981703

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A model describing the relationship between friction coefficient and surface adsorption of a two-component lubricant (i.e. base lubricant and one additive) is developed for boundary lubrication. This model relates the coefficient of friction to the extent of metal-metal contact or, inversely, the fractional surface coverage of the lubricant. Using a suitable adsorption isotherm, an expression for friction coefficient is obtained, relating the friction coefficient to the additive concentration and the adsorption energy. The proposed model and the selected adsorption isotherm are experimentally verified by testing several model additives in a petroleum-base lubricant. An excellent correlation is obtained between the adsorption-free energies calculated from the friction coefficient data and the adsorption-free energies determined from adsorption studies. The ranking order of additives based on friction coefficient is explained in terms of the molecular structure and the structural effects on the adsorption-free energy.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

ISSN:0569-8197    

DOI:10.1080/05698198608981704

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The details are given of a computer model for performing a state-of-the-art tribological assessment of the performance of a lubricated concentrated rolling/sliding/spinning/contact comprising general anisotropic rough surfaces. The name chosen for this program is TRIBOS.

ISSN:0569-8197    

DOI:10.1080/05698198608981705

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor