Thesis (Ph. D.)--Institute of Paper Science and Technology, Georgia Institute of Technology, 2005. / Institute of Paper Science and Technology, Committee Chair. Bibliography:

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

In order to study the detailed spectral intensity distribution of light reflected from a solid-gas interface, the extinction theorem in optics is extended to include an absorbing medium and the thermal motion of the gas molecules near the interface. The theoretical spectral intensity distribution in the region of anomalous dispersion is found to be strongly modified compared to that predicted by existing theory. An important consequence of this theory in the line shapes of the reflected light is the possibility of using recently developed saturation spectroscopic techniques to study atoms and molecules near surfaces. In order to investigate the feasibility of these new techniques for obtaining solid-gas molecule interaction potentials, models of solid-gas interfaces were studied with and without interactions of the type 1/zP (p = 2,3,4), where z is the distance between gas molecules and solid surface. A marked difference in the line shapes of the reflected light among the possible interactions suggests that the forms of interaction at the interface can be measured using known techniques. Furthermore, the possibility of measuring the flow of gas near walls where currently available laser-Doppler anemometers can not spatially reach is investigated. It is shown that the shift and width of the numerically calculated line shape of the reflected light in our model flow is directly related to the mean and the fluctuating velocity fields respectively.

Interactions between proteins and contact surfaces can have important implications in the food industry. Such interactions contribute to the course of fouling of membrane surfaces and they appear to mediate bacterial and spore adhesion to some degree as well. In addition to protein and solution properties, interfacial behavior is strongly influenced by contact surface properties. Among these, hydrophobicity and the potential to take part in acid-base interaction have received considerable attention, but in a quantitative sense we know very little about their respective influences on protein adsorption. It was the purpose of this research to quantify the equilibrium adsorptive behavior of the milk protein β-lactoglobulin as it is influenced by the presence of different contact surface functional groups. Monocrystalline and polished silicon surfaces were modified to be hydrophilic by oxidation and hydrophobic by silanization with dichlorodiethylsilane (DDES), dichlorodimethylsilane (DDMS), and dichlorodiphenylsilane (DDPS), each used at concentrations of 0.82, 3.3, and 82 mM. Surface hydrophobicities were evaluated with contact angle methods. Adsorption isotherms were constructed after allowing each modified silicon surface to independently contact β-lactoglobulin (0.01 M phosphate buffer, pH 7.0) at concentrations ranging between 200 and 2000 mg/L for eight h at room temperature. Surfaces were then rinsed and dried. Optical properties of the bare- and film-covered surfaces, necessary for calculation of adsorbed mass, were obtained by ellipsometry. Plots of adsorbed mass as a function of protein concentration exhibited attainment of plateau values beyond a protein concentration of about 200 mg/L. At high silane concentration, the plateau values associated with surfaces exhibiting ethyl groups were observed to be greatest followed by those exhibiting phenyl, methyl, then hydrophilic (OH) groups. At the low DDMS and DDES concentrations (0.82 and 3.3 mM), adsorbed mass did not increase beyond that value recorded for the hydrophilic surface. This is likely due to some critical spacing of methyl and ethyl groups being required to produce a favorable hydrophobic effect on adsorption. For surfaces treated with dichlorodiphenylsilane, adsorbed mass increased with silane concentration. Apparently, a favorable acid-base interaction effected by the hydrophilic surface is inhibited by the presence of small amounts of methyl and ethyl groups, but somewhat less inhibited by the presence of phenyl groups because the latter have the ability to undergo acid-base interaction. / Graduation date: 1993

Rutherford backscattering spectrometry (RBS) is shown to be an elegant, powerful tool for the chemical characterization of optical coatings. RBS studies of several thin film materials are presented to illustrate the technique's unique abilities, and to show how RBS is best exploited in investigations of thin film stoichiometry and diffusion. The text begins with an introduction to optical coatings and the practical problems encountered in their implementation. The basic principles of RBS are discussed, and the technique is compared to other popular surface analysis tools. The introductory material concludes with a chapter devoted to specific techniques for RBS data and error analysis, including the derivation of a simple formula for determining the optimum thickness of multi-element samples. The accurate stoichiometric measurements provided by RBS give new insights into the chemical structure of ion-bombarded MgF₂ coatings. The analysis shows that lightly-bombarded coatings contain a small oxygen fraction (< 6%), and the absence of this oxygen in opaque, heavily-bombarded samples implies the oxygen compensates for fluorine deficiencies and is therefore an essential ingredient for transparent films. This beneficial oxygen appears to diffuse into the coatings along columnar voids, and the implied compromise between packing density and transparency is discussed. The final chapter takes advantage of the nondestructive depth-profiles provided by RBS. We present the first direct experimental verification of the interfacial oxide layer responsible for the superior adhesion of aluminum to glass, and show that contrary to popular belief, the layer is not an artifact of oxygen adsorbed during the aluminum's evaporation. We then discuss the diffusion of copper through silver films, and show that the migration is enhanced by exposure to the RBS probe beam. Finally, we consider the diffusion of carbon, from graphite substrates, into the voids of porous coatings during the RBS measurements. This effect, like the enhanced copper diffusion, is consistent with a low temperature, measurement-induced anneal; however, we show that the migrant carbon does not alter the chemical structure of the coatings, but instead serves as a convenient, non-intrusive indicator of film porosity.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 141-142). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 141-142). Also available on the Internet.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: powder metallurgy; material evaluation; thermal imaging; NDE; IR radiation and detection; nondestructive testing; thermography; infrared imaging. Includes bibliographical references (p. 86-88).

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 96-104). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxviii, 254 p.; also includes graphics. Includes abstract and vita. Advisor: Taylan Altan, Dept. of Industrial and Systems Engineering. Includes bibliographical references (p. 240-248).