Thesis (M.S.)--University of Wisconsin--Madison, 1960. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 33-34).

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In paper printing, one of the most important aspects for consideration is the control of ink setting rate. Ink setting, depending on ink and press type, is a function of evaporation, curing and removal of the liquid phase by capillary mechanisms steered by the porous substrate. In most cases, absorption by the substrate is the dominating mechanism. Many paper or board substrates are coated with a layer of pigment particles and binders. It is recognised that the void network between these particles has the most important influence on the absorption dynamics. Many aspects of liquid absorption into porous networks are poorly understood. It is shown that it is necessary to characterise both the pore-level structure and the permeability of the network simultaneously. To remove indeterminate effects caused by the usually uneven thin layers of coatings adopted in practice, a novel methodology was developed in this work comprising of a range of unique techniques such as the formation of porous tablet-like blocks of CaCO3. By applying variable compression forces to a compact of fine-ground mineral, a wide ranet> of usable porosities were obtained whilst keeping the surface chemistry and skeletaldefined pore geometry constant. The samples were characterised using mercury porosimetry. The methodology included techniques to study interactions of the structures with industrially and environmentally relevant liquids. An Ink-Surface Interaction Tester (ISIT) was used to analyse ink setting behaviour as a dynamic measure of ink rheology and solids content. This device was modified to provide a measure of the time-dependent extensional strain that is applied to the ink layer in addition to the normally obtained ink tack force values. The importance of the inertial flow regime beyond that of pure viscous flow and its impact in an interconnected network structure, where liquid does not imbibe continuously in a steady laminar flow behaviour at the wetting front, are demonstrated. Mechanisms are proposed which account for the uneven wetting line and its action in leaving parts of the pore network unfilled. Along with other findings, deviations from Lucas-Washburn (LW) scaling are elucidated. These findings are discussed in the context of paper printing and give direction for developing beyond the current limits encountered using environmentally friendly minerals and ink constituents.

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The thesis reports an experimental investigation concerned with the optimisation of mechanical properties in investment cast LM25 aluminium alloy. The effects of melt hydrogen content, filter usage, grain refinement, eutectic silicon modification, heat treatment, pouring and shell preheat temperatures on the structure and tensile properties of LM25 investment cast tensile test specimens were studied. Four series of experiments were conducted to assess the effects of the parameters studied on the structure and tensile properties. The first series established the effect of melt hydrogen content, pouring temperature and shell preheat temperature on the casting porosity, pore morphology and tensile properties. The second series investigated the effect of using a ceramic foam filter on the tensile properties. Pouring temperature and shell preheat temperature were variable parameters in this part of the investigation. The objective of the third series of experiments was to investigate the effect of grain refinement and eutectic silicon modification on the structure and tensile properties. The interaction of these melt treatments with shell preheat temperature and filtration was also studied. In the final series of experiments the effect of heat treatment cycles on the samples produced in the third series of experiments was evaluated in terms of structure and tensile properties. The principal findings of the research were that: shell preheat temperature and hydrogen content are the most important process variables determining the total porosity content; shell temperature affects the structure and, hence, the tensile properties; grain refinement is enhanced as the titanium content increases to about 0.28% but the tensile properties remain unaffected; a modified eutectic Si structure is achieved with 0.01 - 0.02% Sr with optimum Sr addition, based on tensile properties, being 0.01%; and, as would be expected, heat treatment improves the tensile properties of investment cast LM25. On the basis of the inter-relationships between process variables, structural changes and tensile properties observed, an optimum processing route was proposed. Grain refined and modified specimens produced with low hydrogen content and ambient shell temperature had optimum tensile properties when fully heat treated to produce eutectic Si transformation.

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Increased oil exploration necessitates building of conc~ete structures for its production and storage. The effects of crude oil on concrete properties are not well known and little data is available in the published works. This investigation covers HCP, mortar and concrete. First, it studies the effects of cracking and direction of casting on the flow of water or oil of different constitutions through concrete storage tanks. Secondly, it studies the relationships between the pore structure and permeability of HCP, mortar and concrete as influenced by w/c ratio, hydration and aggregate content. OPC was used for the tests. Experimental results show that, in concrete specimens, the flow of water through cracks is generally greater than the flow of crude oil through the same type of cracks. Sorptivity can predict reasonably accurately the flow of liquids and is useful in characterizing the flow of various oil types th:r:( ,ugh HCP, mortar and concrete. No specific oil property appears to control the oil flow through cement composites. Concrete tanks should be lined when used for storing diesel and parafin. Crude oil flow through concrete tank wall was found to be 1.06 - 1.81 times flow through the tank floor. Increasing the w/c ratio, increases the total porosity, pore surface area and threshold radius but decreases the density and does not effect the hydraulic radius. Increasing the age of HCP (w/c = 0.7) from 7 days to 6 months decreases the total porosity, pore surface area, threshold radius and hydraulic radius by 12%, 19%, 71% and 9% respectively, but increases the density by 13%. Adding sand to HcP, reduces the total pore volume and the pore surface area but increases the density. Wax deposits from the crude oils blocked all pore radii <650A, which is called the "critical pore radius" (Pcr). Saturation in crude oil appears to alter the internal structure of the cement composites. Dry curing increased most pore parameters but decreased the strength of the mortars. Permeability of mortar and concrete increases with w/c ratio, applied pressure, aggregate volume concentration and drying temperature but decreases with the test period and hydration. permeability was found to relate reasonably accurately to pore structure using Kozeny's theory provided the pore parameters are for pores of radii >650A.

published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy