Thesis (M.Eng.)(Mechanical)--University of Pretoria, 2004. / Summaries in English and Afrikaans. Includes bibliographical references).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 282-288).

Thesis (M.S.) -- Worcester Polytechnic Institute. / Includes bibliographical references (leaves 60-61).

The object of this research was to study the effect of initial surface -finish and finish mark orientation on intermetallic friction under unlubricated sliding contact conditions. The metal used was mild steel and the parameters investigated were sliding speed and load. Qualitative assessments of wear were also made. The basic apparatus consisted of a rotating disc and an elastically supported slider. The disc and slider each had the same-initial surface finish. Six different surface finishes were examined ranging in roughness from a peak to valley distance of 6.9 thousandths of an inch to 35 microinches R.M.S. Speed was varied from 1.25 to 60 inches per second and normal load from 1.025 to 3.075 pounds. No significant correlation was found, between the theory of Ernst and Merchant and the experimental results. Friction was more dependent on surface parameters affecting load concentration than, on the particular details of each surface asperity. The effects of finish mark orientation were only significant when they produced appreciable load concentration. Friction was found to increase as "wear-in" progressed and remain approximately constant once wear-in was complete. No relation between friction and velocity could be deduced. Wear-in was found to be influenced by initial surface geometry. The sufaces which gave high load concentration at sharp protuberances "wore-in" more quickly than those-with low load concentration. Smooth compatible surfaces which required little surface alteration also wore-in rapidly. Wear debris was found to influence both friction and wear-in. Evidence of mechanical working of debris between the surfaces was obtained. A quasi-harmonic oscillation of the slider supporting system was observed to result from wear-in. The frequency of vibration was a function of disc speed and load. The amplitude of the vibration increased linearly with disc speed up to a maximum value. The magnitude-of this maximum was dependent on normal load. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

The aim of this study was to evaluate the effect of the type of lubricant, its concentration and mixing time with granules on the tablet hardness, ejection force and the lubrication index. Lactose was used as a filler in granules and polyvinylpyrolidone as a binder. Granules were prepared by wet granulation. Three types of talc were used in concentrations 1%, 3%, 5%, 7% a 10% and magnesium stearate in concetrations 1%, 2% a 3% as lubricants. Tablets were produced by tablet press DOTT Bonapace (model CPR-6) with the possibility to measure the force of the upper and lower punch and force-displacement. These values were used for the calculation of the lubrication index. The values of lubrication index were used for the lubricants comparison. The lubrication index with magnesium stearate did not change either with increasing concentration or with mixing time with granules. In case of each type of talc, the lubrication effect rose with increasing concentration but time of the mixing did not have any significant effect on the lubrication potential. Tablet strength decreased with higher lubricant concentration and longer mixing time when magnesium stearate was used. With increasing concentration of the lubricant tablet strength with talc first increased then stagnated or started to decrease. The higher...

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LD2668 .T4 1941 S91 / Master of Science

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