Typescript (photocopy) Includes bibliographical references (leaves 247-270)

Part I discusses the development of an aluminum-magnesium-silicon alloy that may combine strength, extrudability, favorable corrosion resistance with low cost and scrap compatibility. The first part of the study determined the effects of small composition, heat treatment and mechanical processing changes on the ambient temperature tensile properties of the alloy. A combination of magnesium and silicon of about 2%, 1% copper, 0.2% chromium and 0.1% vanadium can produce a T6 alloy with significant higher strength, fatigue and corrosion fatigue properties for both ingot and extrusion than those of 6061 but with only a modest increase in cost. The new alloy has been designated as AA6069. The second part of the study determined the T6 properties of 6069 alloy. The tensile test results of cold and hot extrusions of hollow, solid bars, and high pressure cylinders indicate that the T6 properties ranged from 55-70 ksi (380-490 MPa) UTS, 50-65 ksi (345-450 MPa) yield strength, and 10-18% elongation. It also appears that the fracture toughness and general corrosion resistance in saline environment are comparable or better than those of 6061 T6. Part II attempted to evaluate the formation, formability, thermal and mechanical properties of semi-solid A356, A357 and modified aluminum silicon semi-solid alloys. The semi-solid alloy microstructure was produced in this study by purely thermal treatment rather than conventional and expensive electromagnetic or mechanical stirring. Three heat-up stages in semi-solid treatment were evaluated. Stage I is related to the heating of the alloy in the solid state. Stage II is related to the eutectic reaction. Stage III is related to the heating of the semi-solid slurry. Stage II requires the longest time of the three heat-up stages due to the endothermic reaction on heating. An increase of furnace temperature can greatly reduce the time of stage II. The atmosphere (vacuum, air, argon) of the semi-solid treatment does not appear to greatly affect the T6 properties of semi-solid alloys. The microstructure and T6 properties of semi-solid A356 do not appear sensitive to the homogenization treatments before semi-solid treatment. The porosity of semi-solid ingots and pressed parts increases as the cooling rate decreases in unformed and subsequent-to-moderate pressure forming. The T6 properties basically appear sensitive to voids, with a degradation of properties as the void concentration increases. The formability of A357 may be improved as the spheroidal particle size decreases. Hence, formability may improve with decreasing ingot grain size. The mechanism of coarsening of the solid phase at isothermal temperatures is related to Ostwald ripening and/or "merging" of particles. The mechanical properties of die-casting parts show that the method of thermal treatment to produce a spheroidal microstructure is an effective method for industrial production of semi-solid aluminum-silicon alloys. / Graduation date: 1997

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 1990. / Thesis Advisor(s): Fox, A.G. "March 1990." Description based on signature page as viewed on August 26, 2009. Author(s) subject terms: Aluminum-Lithium Alloys, Microstructural development. Includes bibliographical references (p. 43-47). Also available online.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 100-104).

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Aluminum is a known contaminant of parenteral nutrition (PN) solutions and it has been suspected to play a role in the development of parenteral nutrition associated cholestasis (PNAC). The primary purpose of my research was to monitor the relationship between serum aluminum level and the development of PNAC in the infants with gastrointestinal failure who required PN therapy. The secondary purpose was to develop a neonatal piglet model to compare different doses of aluminum or PN therapy with known aluminum level was associated with the development of PNAC. Sixteen infants with gastrointestinal pathology were enrolled in the study. Serum aluminum and bilirubin (direct and indirect) concentrations were determined on day 0, 7, 14, and 21 of PN therapy. Five of sixteen (31.3%) infants developed PNAC by day 21. Serum aluminum levels in infants receiving PN peaked at day 7 of therapy and declined thereafter. There was no direct correlation between serum direct bilirubin and serum aluminum levels. Twenty-four piglets, 2 to 4 days old, were placed into four groups: Control group (n=5); Low Al (aluminum) group (n=7), intravenous (iv) injection with aluminum dose at 20 ìgkg-1day-1; High Al (aluminum) group (n=6), iv with aluminum dose at 1500 ìgkg-1day-1; PN (parenteral nutrition) group (n=6), PN solutions with a mean aluminum intake at 37.8±14.3 ìgkg-1day-1. The experiment period was 21 days. Serum bilirubin was significantly (p<0.05) elevated in the High Al and PN groups. Liver aluminum concentration was significantly (p<0.05) elevated in all the experimental groups and the relationship was dose dependant. Serum, and urine concentrations of aluminum were significantly (p<0.05) elevated in High Al but not the Low Al and PN groups. Serum aluminum concentration was not correlated with serum total bilirubin levels. Cholestasis developed by 21 days in five infants and in the piglets of two experimental groups (the High Al group and the PN group). High dose injection of aluminum may play a role in the development of PNAC in the neonatal piglets. The impact of aluminum may depend on the amount of pareternal aluminum intake and the presence of other potential factors such as lack of enternal feeding and individual physiological abilities.

Anodized aluminium oxide may be chemically treated to yield a uniform self-organized distribution of pores with a specific pore diameter. The thickness of in-house anodized alumina and its pore size can be modified by changing the electrolyte, the temperature of the electrolyte, the time of anodization and the potential over the anodized plates.  In this thesis, a method for anodized aluminium oxide (AAO) was optimized for creating custom-made porous alumina membranes and coating them with TiO2 and polyethylene glycol (PEG). The purpose of finding a method to create porous alumina oxide with specific pore diameters was to eventually use these membranes for use in contact with human living tissue, allowing wanted nutrients and fluid to pass in and out.      SEM images showed that a reproducible method has been established for the membrane production, where the pore diameter is ~ 300nm and the thickness of the oxide is approximately 100µm. The SEM images also showed that the pores are stable and uniform over the entire aluminum plate where they are initially produced.      As a test for biocompatibility, the membranes were implanted into the hipbone of pigs. The histology test showed fibrosis around the location where the membranes were placed. An observation during the extraction was swollenness in the surrounding tissue, which indicates inflammation around the implant. In this respect, the membranes cannot be used for the purpose intended.

Aluminum is the most common metal in the world and its high strength to weight ratio, along with excellent corrosion resistance, can provide efficient solutions for the design and rehabilitation of highway bridge structures. A reduction in a structure’s self-weight, when using aluminum, is advantageous for the rehabilitation of existing structures requiring an increased live load capacity and for rapid bridge replacements whereby larger, lightweight components can be installed with limited disruption to traffic. Aluminum structures and components offer the potential for lower life-cycle costs due to the favourable corrosion resistance, allowing for less maintenance over the life of the structure. One significant disadvantage of aluminum is that it is more susceptible to fatigue damage in relation to steel. Being a newer design material for bridge structures, compared to steel, and due to its limited use in the past, limited fatigue testing has been conducted to date. Bridge design codes and specifications employ different approaches for establishing fatigue design (S-N) curves for aluminum structures. The British and European design standards use a two-slope design curve, with a shallower slope in the high cycle range, implying that fatigue damage accumulates at a different rate at lower stress ranges. The Aluminum Association in the United States uses a more conservative approach, assuming a single-slope design S-N curve, by simply extending the curve past the constant amplitude fatigue limit at the initial slope. Limited testing under variable amplitude loading in the high cycle range has been completed to date, where a second slope could be warranted. A new chapter of the Canadian Highway Bridge Design Code (CSA-S6) on aluminum structures is currently under development. The research presented herein provides recommendations regarding the correction factors required for fatigue design of aluminum. In addition, fatigue testing and fracture mechanics analysis studies are performed to further investigate the use of a two-slope S-N curve for the fatigue design of aluminum highway structures.

Aluminum is a known contaminant of parenteral nutrition (PN) solutions and it has been suspected to play a role in the development of parenteral nutrition associated cholestasis (PNAC). The primary purpose of my research was to monitor the relationship between serum aluminum level and the development of PNAC in the infants with gastrointestinal failure who required PN therapy. The secondary purpose was to develop a neonatal piglet model to compare different doses of aluminum or PN therapy with known aluminum level was associated with the development of PNAC. Sixteen infants with gastrointestinal pathology were enrolled in the study. Serum aluminum and bilirubin (direct and indirect) concentrations were determined on day 0, 7, 14, and 21 of PN therapy. Five of sixteen (31.3%) infants developed PNAC by day 21. Serum aluminum levels in infants receiving PN peaked at day 7 of therapy and declined thereafter. There was no direct correlation between serum direct bilirubin and serum aluminum levels. Twenty-four piglets, 2 to 4 days old, were placed into four groups: Control group (n=5); Low Al (aluminum) group (n=7), intravenous (iv) injection with aluminum dose at 20 ìgkg-1day-1; High Al (aluminum) group (n=6), iv with aluminum dose at 1500 ìgkg-1day-1; PN (parenteral nutrition) group (n=6), PN solutions with a mean aluminum intake at 37.8±14.3 ìgkg-1day-1. The experiment period was 21 days. Serum bilirubin was significantly (p<0.05) elevated in the High Al and PN groups. Liver aluminum concentration was significantly (p<0.05) elevated in all the experimental groups and the relationship was dose dependant. Serum, and urine concentrations of aluminum were significantly (p<0.05) elevated in High Al but not the Low Al and PN groups. Serum aluminum concentration was not correlated with serum total bilirubin levels. Cholestasis developed by 21 days in five infants and in the piglets of two experimental groups (the High Al group and the PN group). High dose injection of aluminum may play a role in the development of PNAC in the neonatal piglets. The impact of aluminum may depend on the amount of pareternal aluminum intake and the presence of other potential factors such as lack of enternal feeding and individual physiological abilities.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 158-168).