An investigation of the sodium aluminate-sodium nitrate system was conducted. The effect of sodium nitrate on the solubility of aluminum is important to the retrieval of waste from the tanks at the Hanford nuclear facility located in the state of Washington. Experiments were performed on the NaAlO2 - NaNO3 - H2O system at 25?aC and 50?aC. The results obtained from these experiments were then compared to predictions from the Environmental Simulation Program (ESP, OLI Systems, Inc.) and available literature data. The presence of sodium nitrate increased the solubility of sodium aluminate in water. Sodium nitrate exhibited a greater effect on the solubility of sodium aluminate at higher temperature. Error analysis of the experimental data was performed and indicated that the experimental molalities were accurate to within an average of +3%. The measured data will be used to improve existing databases for ESP.

No description available.

No description available.

It was the purpose of this investigation to study the effect of addition agents on the electrodeposition of aluminum on copper from a fused bath of 80 per cent aluminum chloride and 20 per cent sodium chloride. The agents added and the concentrations studied were lead chloride, 0.5 and 1.0 per cent; aluminum thiocyanate, 0.5 and 1.0 per cent; chromic oxide, 0.5 per cent; sodium cyanide, 0.1 and 0.5 per cent; and vanadium pentoxide, 0.1 per cent. The electrolysis was carried out in a 1000-millimeter beaker in a furnace heated by a 1000-watt element. The plating cell was fitted with a tight lid through which the electrodes could be adjusted. The optimum current density range while plating from a bath of 80 per cent aluminum chloride and 20 per cent sodium chloride was 8.2 to 21.0 amperes per square foot. When aluminum was electroplated from a bath of 75 per cent aluminum chloride, 20 per cent sodium chloride, and 5 per cent lithium chloride, the plates did not adhere to the base metal. Also, the plates corroded to the base metal in a few days. The optimum temperature was found to be 356 °F. Lead chloride, when added at a concentration of 0.5 and 1.0 per cent, produced a smoothening effect. The plates obtained at the former concentration were smoothest. However, the plates were rather easily corroded by the atmosphere. In contrast, chronic oxide at 0.5 per cent did not improve the smoothness of the plate but did improve considerably the corrosion resistance of the plate. Addition of aluminum thiocyanate caused formation of a black powder which was non-adherent. Sodium cyanide at 0.1 and 0.5 per cent did not improve the ductility and corrosive resistance of the plate to any extent. Vanadium pentoxide gave corrosive resistance and ductility to the deposit at lower current densities of 10 to 100 amperes per square foot and thin mirror plates at current densities between 100 and 500 amperes per square foot. The vanadium pentoxide was used at a concentration of 0.1 weight per cent. In attempts to protect the plates from corrosion, applications of chemical treatment to the aluminum plate failed, as also did an application of lacquer. The results obtained with the addition of lead chloride, chromic oxide, and vanadium pentoxide warrant further study to determine optimum operating conditions and limits. / Master of Science

Call number: LD2668 .T4 1978 A67 / Master of Science

No description available.

To reduce CO2 emissions the cement industry has for decades diluted the Portland cement fraction of concrete binders with Supplementary Cementitious Materials (SCM). Defining the reactivity of these aluminosilicate-based materials and their interaction with clinker phases has however challenged the research community and limited their replacement levels. In the present study, to quantify the reactivity of SCMs during early hydration, aluminosilicate glasses with compositions representative of blast furnace slag and fly ash systems were synthesised and exposed to different activator solutions in a continuously stirred closed system reactor for a period up to 3 h. Solution compositions were measured from the very first minutes of dissolution with complementary solid surface analysis. The experimental conditions were designed to avoid precipitation, however an initial Ca maximum in the first 30 min of exposure to the activating solution was a common feature in most dissolution profiles with a subsequent rapid decline, most likely attributable to Ca-reincorporation on the reacting surface. Surface specific analysis confirmed Ca enrichment on the surface and also detected Al enrichment, suggesting the formation of a Ca-modified aluminosilicate phase by a dissolution reprecipitation mechanism on the surface of the glass. Differing chemistries are thought to be responsible for the Ca and Al re-integration on the reacting surface depending on the pH of the solution; near-neutral conditions favour Ca-readsorption and surface condensation reactions, whereas alkaline solutions favour Ca-reintegration via covalently bound phases. The Ca concentration in solution was also observed to control glass alteration. Decreased dissolution rates were in fact observed as Ca concentrations in solution were increased supporting the formation of a C-A-S-H phase on the surface, the formation of which was instead suppressed when a Ca chelating chelating agent (EDTA) was added to the solution resulting in increased glass dissolution. Experiments using in situ AFM and LAOICPOMS are also reported and the significance of the findings to the early hydration reactions of a blended cement system is discussed.

published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

The need to increase vehicle performance, particularly fuel efficiency, has led to an increased interest in using lightweight metals for vehicle structural components. Lightweight aluminum alloys offer the potential to significantly reduce vehicle mass when structural components that use steel are replaced. Mass reduction is a very efficient route to increase vehicle performance. In vehicles with traditional powertrains, mass reduction can increase fuel efficiency. In vehicles with electrical powertrains, mass reduction can increase driving range. Regardless of the specific structural application, the best performance of any aluminum alloy is only obtained by achieving a microstructure that produces the best material properties. For wrought aluminum alloys, hot and cold deformation steps are critical to obtaining a desirable microstructure prior to the forming of a final component. For sheet material, the first step in controlling the final microstructure is microstructure evolution during hot rolling the cast ingot material. Hot rolling precedes cold rolling of the sheet to final thickness in most commercial sheet manufacturing operations. Microstructure during hot rolling is difficult to study because it requires a combination of high temperatures, fast strain rates and large strains to do so. Furthermore, specimens for microstructural examination must be extracted from these conditions while retaining the characteristics of the specific conditions that are to be studied. Hot torsion testing is the traditional approach to meeting these experimental requirements. In this investigation, a new hot torsion testing instrument is designed, fabricated and validated to enable future experiments that will elucidate microstructure evolution under conditions pertinent to hot rolling. This new instrument is integrated with computerized control and data acquisition systems. Validation experiments were conducted to characterize its capabilities. It is concluded that the completed instrument meets the requirements necessary to study plastic deformation and microstructure evolution in aluminum alloys under conditions relevant to hot rolling. / text

Two equalisation or reheating temperatures (1050°C and 1150°C) and three equalisation or reheating times (53 min, 318 min, and 1333 min) were applied to three V- and V-Ti- microalloyed steels, which contain a low carbon content (0.067 ~ 0.073 wt%) and high nitrogen content (0.017 ~ 0.021 wt%), by the simulated direct charging or conventional cold charging processes. The experimental results show that in directly charged V-microalloyed steels, MnS provides the main pinning effect but does not have a sufficient ability to prevent the austenite grains from growing during the equalisation. Because of the slow precipitation, AIN only precipitates at the longest equalisation time and is the main compound which has an obvious pinning effect on the austenite grain growth in V-microalloyed steels. Austenite grain growth appears more likely to be abnormal as a result of the direct charging than of the cold charging due to the precipitation of fine AIN particles during the phase transformations. The experimental results also show that the longer equalisation or reheating time in the furnace does not result in a significant change in the microstructures and in the austenite grain size, because of the precipitation of AIN during equalisation or reheating. However, in V-Ti-microalloyed steels, the existence of titanium can promote the precipitation of complex (Ti×V₁₋×)N particles during equalisation or reheating. In the cold charged V-Ti-N microalloyed steel, the fine austenite grains produced (<10μm) can be observed after the reheating and water-quenching due to the significant pinning effect of (Ti×V₁₋×)N. When the reheating time of V-Ti-N microalloyed steels at 1150°C is longer than 318 min, the coarsening of (Ti×V₁₋×)N precipitates occurs and leads to abnormal austenite grain growth. The TEM results also show that cruciform (Ti×V₁₋×)N particles can only be found indirectly charged steels but not in cold charged steels.