Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 227-233).

The aim of this study was to determine the influence of alumina increase on the functioning of casting powder during continuous casting. Two aspects of the powder's performance were experimentally measured, namely the influence of alumina on the viscosity and the crystallisation behaviour. These two aspects were then related to the in-mould functioning of the casting powder with the aid of literature references. Casting slag must provide lubrication between the mould surface and the thin steel shell. Alumina increase will cause viscosity increase in casting slags and will hinder lubrication when the inflow of casting slag into the mould/strand gap deteriorates. Heat transfer across the gap is determined by the amount of solid casting slag and the form (glass or crystalline) thereof. Heat transfer across a crystalline material may be up to seven times lower than that across a glass phase. The increased alumina will serve to increase the ratio of glassy phase to crystalline phase in the gap, so increasing the heat transfer. To determine the true extent of alumina increase with modern clean steel practice, samples were taken from the moulds of both the VI and V2 continuous casters at ISCOR Vanderbijlpark. The influence of this alumina increase on the viscosity and the crystallisation behaviour of the casting slag were experimentally measured. Viscosity measurements were done with a rotating bob viscometer (in a vertical tube furnace) on two commercial casting powders (with increasing AI2O3 content). Viscosity prediction models were evaluated with the data from the measured viscosity values. Crystallisation measurements were done by quench experiments with the aid of the hot thermocouple technique. Crystallisation behaviour after a specified heat cycle was presented as the percentage opaque material (crystalline) to vitreous material (glassy) measured with an optical microscope. For the seven sequence casts during which samples were collected from the mould, it was found that the alumina content of the casting slag reached a steady-state value within the first ladle (first 40 minutes) with an increase of 3 to 4 mass %. The influence of a 4 mass % alumina increase on the measured viscosity is small enough that proper lubrication function of the slag will not be negatively affected. Viscosity prediction models vary in their accuracy and are limited with respect to the composition range of the casting powder and the temperature range for which they are valid. The increased alumina content was found to have a strong influence on the percentage crystalline material present. After the sample was heated to 1300°C, kept there for 10s, and then quenched, the crystalline material will decrease from 60 % to 30 % for 5 mass % alumina added. This decreased crystalline material present may notably increase heat transfer. Full crystallisation does not occur at a single temperature, and crystallisation occurs over a temperature interval (of up to 200°C). This means that crystallisation temperature values quoted by casting powder manufacturers depend on the heat cycle and the technique used during crystallisation measurements. Several crystalline phases are usually present in solidified casting slag and these crystalline phases are strongly influenced by the alumina content: the stable crystalline phases may change as alumina content increases. For the current alumina increase in casting powders the effect on viscosity is small, while crystallisation behaviour may be influenced to a greater extent. / Dissertation (M Eng (Metallurgical Engineering))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted

A common goal for industrial manufacturers is to create a safer working environment and reduce production costs. One common method to achieve this goal is to drastically reduce cutting fluid use in machining. Recent advances in machining technologies have made it possible to perform machining with minimum-quantity lubrication (MQL). Drilling takes a key position in the realization of MQL machining. In this study the effects of using MQL in drilling AISI 1018 steel with HSS tools using a vegetable based lubricant were investigated. A full factorial experiment was conducted and regression models were generated for both surface finish and hole size. Lower surface roughness and higher tool life were observed in the lowest speed and feed rate combination.

No description available.

An experimental study of ceramic lubrication through the concept of tribopolymerization from the vapor phase is presented. Four vinyl monomer additives were studied, i.e., vinyl acetate, diallyl phthalate, lauryl methacrylate, and vinyl octadecyl ether. The liquid additives were heated, vaporized, and delivered to an enclosed alumina-on-alumina "pin-on-disk” contact region by a stream of dry nitrogen gas. Alumina ball wear reductions of up to 99% were observed and total wear reductions (ball and disk) of over 70% were also common. Colorful surface films visible to the naked eye were examined. Monomer concentration does not appear to have an effect over the range examined. But, higher monomer delivery temperatures have a significant beneficial effect in reducing wear. Selective FTIRM analysis shows evidence of both polymerization and monomer reactions with the alumina surface. It is believed that the surface films formed reduce adhesion and therefore decrease both wear and friction. The development, design, and construction of a high load, high speed, high frictional heat generation pin-on-disk machine is presented. A very successful geometry has been created and recommendations for added instrumentation and its future use for both liquid and vapor phase tests are presented. / Master of Science

The lubrication of ceramic materials is a difficult problem; conventional lubrication techniques are limited or often ineffective. Therefore, the concept of tribopolymerization -- originally proposed by Furey and later modified by Furey and Kajdas -- is used as a new approach to boundary lubrication of ceramics. In this approach, potential polymer-forming compounds are used in minor concentrations in a carrier fluid, which polymerize at the contact region under the sliding action to form a protective layer at the contact. Selected monomers -- including one condensation type, C₃₆ dimer acid/ ethylene glycol monoester, and five addition type, i.e., lauryl methacrylate, diallyl phthalate, vinyloctadecyl ether, vinyl acetate and methyl-2-acrylamido-2- methoxy acetate, were used at 1% concentration in hexadecane in pin-on-disk tests with sliding alumina and zirconia ceramic systems. Results showed that wear reductions of alumina by up to 80% were achieved at room temperature. At elevated temperatures (up to 150°C), the monomers were also effective; one of the monomers reduced wear by over 90% at higher temperatures. In the zirconia system, the monomers in general were also effective in reducing wear, but not to the same extent as with alumina. There was no significant effect of the monomers on friction. Detailed surface analytical studies of the worn surfaces lubricated with the monomer solutions using Fourier transform infrared microspectroscopy, X-ray photoelectron spectroscopy and mass spectrometry showed the complex nature of tribochemistry involved in the antiwear action of these monomers. In addition to the polymerization, evidence of chemical reactions of the monomers with the ceramic substrate was found. Using an advanced infrared microscope system, surface temperatures at the lubricated contacts of alumina-on-sapphireand zirconia-on-sapphiresystems were measured for selected monomers. In general the temperatures were very low. Theoretical estimations of surface temperatures using Vick’s model were also carried out for several systems (including the ones studied in the past) and the role of surface temperature in the anti-wear action of the monomers was examined. The relationship is complex; but the general trend suggests that temperatures are important for tribopolymerization of the monoester, whereas not so much so for the addition monomers. A molecular modeling software -- CHEM-X -- was also used to obtain additional insight into the mechanisms of anti-wear action of the monomers. In this exploratory study, 3-dimensional shapes of the monomers, their polymerization mechanisms, and possible orientation of a selected monomer on polymerization mechanisms, and possible orientation of a selected monomer on a ceramic surface was examined. Possible mechanisms of anti-wear action of these monomers are proposed. For the monoester, the mechanism involves (a) an initial adsorption of the carboxylic end of the molecules on the surface, (b) chemical reaction with the surface to form a soap, and (c) the formation and outward growth of oligomer/polymer chains somewhat similar in structure to a Langmuir-Blodgett multi-layer. The mechanism of anti-wear action of the addition monomers is believed to be connected to the negative-ion radical action mechanism (NIRAM) as proposed by Kajdas. According to this mechanism, exoelectron emitted during sliding initiate tribopolymerization of vinyl monomers, and monomers polymerizing only by anionic or free radical mechanisms are capable of tribopolymerization on the ceramic surfaces. It is proposed that the formed polymeric products act as a binding medium for fine wear debris particles generated during sliding. As a result, a strongly bonded debris layer -- somewhat similar to a ceramic powder reinforced polymer composite -- forms on the surface. This layer provides protection to the sliding surfaces against wear. / Ph. D.

by Ha Fu-Lam. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 61-63.

by Yin Wai Yin, Juanna. / Questionnairies in Chinese. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 106-108). / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.iii / LIST OF ILLUSTRATIONS --- p.vi / LIST OF TABLES --- p.vii / Chapter / Chapter I. --- INTRODUCTION --- p.1 / Methodology --- p.5 / The Interviews --- p.5 / The Questionnaire Survey --- p.6 / Chapter II. --- BACKGROUND ANALYSIS --- p.7 / The Company --- p.7 / The Royal Dutch/Shell Group --- p.7 / The lubricant division --- p.8 / Willie --- p.9 / The Market --- p.10 / Market Size --- p.10 / For initial fill --- p.10 / For testing purpose --- p.11 / For oil change --- p.11 / Market Share --- p.13 / At the manufacturers' and traders' level --- p.13 / At the end users' level --- p.15 / Hydraulic Oil Distribution Channels --- p.17 / Machine Manufactures' Buying Channels --- p.17 / Traders' Buying Channels --- p.18 / End-users' buying channels --- p.18 / Shell Tellus Hydraulic Oil --- p.19 / Strengths of Shell Tellus Oil --- p.19 / Weaknesses of Shell Tellus Oil --- p.20 / Opportunities of Shell Tellus Oil --- p.21 / Threat of Shell Tellus Oil --- p.21 / Competitors --- p.22 / Strengths of Competitors --- p.22 / Weaknesses of Competitors --- p.23 / Marketing Programs of Competitors --- p.23 / Price of Competitors --- p.24 / The Customer --- p.25 / Who are our customers ？ --- p.25 / Machine Manufacturers (Or called builders by the insider) --- p.25 / Machine Traders --- p.25 / End-users --- p.25 / Purchase Decision --- p.26 / For initial fill --- p.27 / For oil change --- p.27 / Buying Criteria --- p.28 / Machine builders / traders --- p.28 / End-users --- p.28 / Customers' and Non-customers' General Perception --- p.29 / Machine Builders / Traders --- p.29 / End-users --- p.31 / How do customers compare Shell with competitors ？ --- p.32 / Overall impression --- p.32 / Opinions on specific items --- p.32 / Other Environmental Factors --- p.34 / Export --- p.34 / The stagnant plastic industry --- p.35 / The increasing import tax of China --- p.35 / Re-export --- p.37 / Import --- p.37 / Chapter III. --- CHANNEL CONFLICTS --- p.38 / New and Existing Relationships --- p.40 / Relationship Reevaluation Triggers --- p.41 / The role of perceptions and behaviors --- p.41 / Asymmetrical power relationships --- p.42 / Performance of channel members --- p.43 / Goal incongruity --- p.44 / External influences on conflict --- p.44 / Partnership Advantage Evaluation --- p.45 / Marketing enhancements --- p.45 / Cost reductions --- p.46 / "Managing uncertainty (Williamson, 1981)" --- p.46 / "Protection of specific assets (Williamson, 1981)" --- p.47 / Formulating Channel Strategies --- p.47 / Relationship Components --- p.48 / The role of manufacturer - Shell --- p.48 / The role of distributors --- p.49 / The role of account managers --- p.50 / Programs and Action Plans --- p.52 / Essential elements --- p.53 / Capability-building programs --- p.54 / Incentive programs --- p.55 / Measuring Performance --- p.56 / Feedback --- p.57 / Chapter IV. --- THE MARKETING PLAN --- p.58 / Marketing Objectives --- p.59 / Product --- p.60 / Objectives --- p.60 / Strategy --- p.60 / The product itself --- p.60 / The services --- p.62 / Price --- p.63 / Objective --- p.63 / Strategy --- p.63 / Price setting --- p.63 / Reselling price control --- p.64 / Place --- p.65 / Objectives --- p.65 / Strategy --- p.65 / Promotion --- p.66 / Objectives --- p.66 / Strategies --- p.66 / Advertising --- p.67 / Sales promotion --- p.68 / Public relations --- p.69 / Chapter V. --- CONCLUSION --- p.71 / APPENDIX --- p.73 / BIBLIOGRAPHY --- p.106

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Masters of Science in Engineering, 2016 / This research is focused on optimizing the surface integrity of Ti-6Al-4V using advanced carbide inserts and minimum quantity lubrication (MQL). Experiments were designed to machine twenty Ti-6Al-4V blocks under dry and MQL lubricating conditions using innovative cemented carbide inserts produced by Liquid Phase Sintering (LPS) and Spark Plasma Sintering (SPS). The cutting speed, feed rate, and depth of cut, were considered as machining parameters, while the cutting force, temperature, tool wear, surface roughness and residual stress were considered as performance characteristics. The results obtained for surface roughness and residual stress measurements were used to analyze the surface integrity of the machined Ti-6Al-4V samples. The influence of sintering techniques and milling parameters on performance characteristics and surface integrity were investigated from experimental results obtained. Discrepancy in behavioral trends with respect to lubricating conditions was also investigated. The analyses of milling results showed that cutting speed played a major role in the optimization of surface integrity of the Ti-6Al-4V work pieces followed by the depth of cut. The results also showed that the LPS inserts performed better than the SPS inserts due to their better mechanical properties (higher fracture toughness (KIC) and transverse rupture strength). The application of MQL was also observed to significantly reduce milling temperatures resulting in better surface integrity. However, an optimized surface integrity of the Ti-6Al-4V samples was achieved during MQL milling with the 10Co-L insert at a low finishing speed of 75m/minute and a reduced depth of cut of 0.5mm.

"Two most important events in the history of lubrication theory are attributed to Reynolds and Sommerfeld. Reynolds derived the governing equations for lubricating films in simplifying the Navier-Stokes equations considering thin-film effects. Sommerfeld obtained a closed form analytical solution to the Reynolds equation for the long bearing (one-dimensional case) with fixed constant eccentricity which results in a point symmetric pressure profile compared to an arbitrary (ambient) level. In attempting to reconcile with experimental evidence, Gumbel advanced the argument that sub-ambient pressure in a fluid film is not possible. On the basis that the fluid film would rupture, he put forth that the sub-ambient portion of the Sommerfeld solution should be discarded, a proposition that is commonly recognized as the half-Sommerfeld solution (of Gumbel). Ever since Gumbel suggested this improvement, much interest remains regarding the physical process of rupture in bearing lubricating films. In lubrication literature, cavitation is used interchangeably with rupture to indicate a condition in which an abundance of a gas phase, essentially ambient air, is present in a portion of the bearing clearance. A cogent two-phase morphology for addressing cavitation in long bearings is postulated in order to predict time-dependent fluid behavior from an initial state that is a generalization of Gumbel’s half-Sommerfeld solution. The ultimate steady-state is presumed to satisfy the hypothesis of Swift and Stieber that an ambient condition is reached by the rupture point at an unspecified location simultaneously with a vanishing pressure gradient. A trans-rupture continuity equation, as proposed by Olsson, determines a formula for the speed of a moving rupture point requiring a specific model of the two-phase flow in the rupture region. Employing an adhered film model, sequential application of Olsson’s equation to the rupture points of the intermediate states between the half-Sommerfeld and Swift-Stieber states renders an interpretation of a time-dependent progression towards a steady-state solution. Closed form analytical formulas, which readily combine to provide an exact solution to the Reynolds equation are derived with the start (formation point) of the full-film other than the customary bearing maximum gap and with the rupture point at any assigned intermediate location. Each valid solution for an intermediate state yields an invariant flux that must satisfy a window of constraints to exclude the possibility of sub-ambient pressures. A complete set of such valid solutions exists for each fixed eccentricity and can be depicted as a contour plot of the invariant flux with formation and rupture points as coordinates. The method can readily be extended to two-dimensions, offering a promising alternative to the Elrod cavitation algorithm, which is commonly used in more comprehensive bearing analyses."