Aerodynamic lubrication

The lubricant dynamics can alter the nanoscale aerodynamics of the slider. Conversely, the lubricant morphology and dynamics may be altered because of the presence of the slider. For these types of applications, a molecule-level understanding of the lubricant interaction with nanoscale airbearing and solid surfaces is critical. The HDD industry must cope with problems of lubricant film uniformity, roughness [5], durability [6], and stability [7] in order to achieve its goal of increasing areal density. 

Berry, J., Kline, L., Naini, V., Chaudhry, S., Hart, J., and Sequeira, J. (2004), Influence of the valve lubricant on the aerodynamic particle size of a metered dose inhaler, Drug. Dev. Ind. Pharm., 30, 267-275. 

For most conditions, the best effect is obtained when there exists a thick film of fluid between the moving surfaces affording efficient aerodynamic, hydrodynamic, or elastohydrodynamic lubrication. If the lubricating film is thinned or broken by operating conditions or system failure, additional protection is afforded by adsorbed films through boundary lubrication. Finally, under extreme conditions, protection against seizure and complete failure may be obtained as a result of chemical processes that produce weak oxide, sulfide, or phosphate, surface layers that can be more easily sheared that direct metal-metal contacts. For hydrodynamic and elastohydrodynamic lubrication, careful... 

Stanton s breadth of outlook is demonstrated by the fact that in 1923 he published a book entitled Friction in which he included the fundamentals of aerodynamic friction as well as fluid lubrication. In 1927 he reported to Section G of the British Association the results of a series of experiments in which the relative displacement of a bearing and journal were measured by electrical inductance. Up to an eccentricity ratio of about 0.5 the agreement between observation and theory was reasonably good but a further increase produced a deviation of the point of nearest approach towards the crown of the bearing instead of in the lateral direction as predicted by Sommerfeld s theory. This led to considerable controversy until it was accepted that the negative pressures postulated by this theory could not be withstood by lubricant. 

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