The main aim of this project was to investigate the role of Fusarium solani in aqueous cutting fluid and increase understanding about the ecology of this organism in coolants. By adapting cell-line bioassay techniques to the direct testing of coolant emulsion, the role of Fusarium solani in cutting fluid toxicity was determined. The potential of fungal strains enhancing cutting fluid toxicity was investigated by fungal toxigenicity screening, to assess any potential for fungal species isolated to produce mycotoxins. 32 contaminated cutting fluid samples tested revealed 66 % fungal contamination and Fusarium solani was isolated from 81 % of these, highlighting the significance of this species in coolants. Using brine shrimp and cell-line bioassays, none of the fungi isolated were toxigenic, although Fusarium solani culture extracts were slightly toxic to cell-lines (min. cytotoxic dose 12.5-25 ug/ml). Using thin layer chromatography, it was revealed that the isolate Fusarium solani ISL-45 / IMI 360547 was not producing trichothecenes in culture, and that a maroon pigment normally produced at pH < 4 was responsible for slight cytotoxicity. It was revealed that pigment production was only stimulated in cultures less than pH 4 in the presence of excess phosphate. By assaying cutting fluid using cell-lines it was found that growth of Fusarium solani reduced cutting fluid toxicity twofold after 14 days growth and that fungal biodeterioration of vegetable oil and ethylene glycol was responsible for the toxicity decrease. Cutting fluid not supplemented with yeast extract or other nitrogenous material was unable to support growth of Fusarium solani demonstrating that there was an obligate requirement for an external assimilable nitrogen source in addition to nitrogenous cutting fluid constituents. Fusarium solani biomass yields were highest in cutting fluid experiments supplemented with iron / aluminium swarf and inert beads. Biomass yields were poor in cutting fluid containing no swarf or inert material suggesting that surfaces promote fungal adhesion and accumulation of mycelium. Although swarf metal was stimulatory to growth, cutting fluid treated with dissolved swarf materials was inhibitory to growth. II In metal ion tests; Ca2+, Mg2+ and Mn2+ had little effect on fungal physiology whereas A13+, Cu2+, Fe3+, Ni2+ and Ti3+ were very toxic (min. inhibitory dose M.I.D. < 2mM) and C~+, Co2+, Fe2+, Pb2+ and Zn2+ were moderately toxic (M.I.D. 2-10 mM). 0.5 mM Pb2+ and Zn2+ were associated with increased production of maroon pigment, by Fusarium solani, in media containing glucose. Water hardness was found to have little or no effect on fungal physiology although coolant emulsion stability was reduced with Ca2+ concentrations exceeding 5 mM.

This work investigated material corrosion by nuclear reactor coolants, including pressurized water reactor (PWR) coolant, boiling water reactor (BWR) coolant, high-temperature steam, lead-bismuth eutectic (LBE), and molten salt. Novel cladding materials for accident tolerant fuel (ATF) and additive manufacture (AM) Ni-based alloy were studied in water coolants. Similarly, the ATF material and Ni-based alloys were also examined under high-temperature steam to understand the corrosion behavior in beyond design basis accident (BDBA) scenarios. In addition to isothermal corrosion, stress corrosion cracking (SCC) and oxide layer in situ measurements were also conducted. Unlike conventional studies in liquid LBE that focused on Fe-based alloys, the present studies also investigated Ni-based alloys to explore the Ni content effects on the corrosion by LBE at high temperatures under saturated oxygen conditions. In molten salt environments, the corrosion behaviors of both Ni-based and Fe-based alloys were investigated. This study developed a redox potential range for mitigating corrosion by using a redox couple of UF4 /UF3 and a novel approach of potential measurements against F2/ F- potential experimentally. / Doctor of Philosophy / This work focuses on material degradation in harsh and extreme nuclear environments, including light water reactors and advanced reactors such as molten salt and liquid metal coolant reactors. Given the renewed interest in advanced nuclear reactors as a resource of clean energy, advanced material development, including structural, fuel, and coolant materials, has become a significant and trending research area. Based on our past experiences, we have seen the detrimental effects of material failure due to corrosion. Systems are inherently safe in the absence of material degradation. Nevertheless, this is an idealistic thought, as corrosion is inevitable. Therefore, this research focuses on corrosion mitigation, as absolute material preservation is impossible. This work includes corrosion studies in aqueous environments in light water reactors and advanced nuclear reactors under normal operation and extreme conditions such as accident environments. Much of this work provides insights into material corrosion behavior and mitigation that helps nuclear reactor operators ensure safe operations. Commercially available alloys such as SS316, Hast. X and Hast. N were examined in primary water, molten salt, high-temperature steam, and liquid bismuth environment and model Fe-Cr-Si alloys were investigated in water and steam to compare the corrosion mechanisms.

Continual development of internal combustion engines requires greater performance from liquid coolants and heat exchangers to maintain optimal temperature. For the purpose of experimental testing of traditional, compact, and microchannel heat exchangers, a test facility has been designed, constructed, and utilized. The facility includes equipment and instrumentation necessary to create operating conditions and record data primarily for testing plate-fin brazed aluminum heat exchanger where heat is being transferred from liquid to air. Other arrangements of heat exchangers could be tested as well with some modifications. Initial tests were performed at several specified operating conditions for three liquids: water, a traditional glycol based Extended Life Coolant (ELC), and a new Glycol Free Coolant (GFC) in an attempt to characterize their heat transfer ability. Results of the tests found that the product of overall heat transfer coefficient and heat exchanger area (UA) was very similar for GFC and water, and it was less for ELC by a narrow margin of 1.3% difference on average. Uncertainty due to instrumentation accuracy was calculated to be 1.8% on average making the results overall UA unverifiable. Measured pressure drop across the heat exchanger which is proportional to required pumping power was found to be 13.5% higher for GFC than ELC at nominal conditions. The GFC offers similar heat transfer performance and marginally increased pumping power requirements compared to the traditional ELC. Due to similar heat transfer performance and the small effect of pressure drop, GFC would be good alternative to ELC due to its less toxic composition.

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Traditional liquid coolants used in metal machining are known to contain chemical carcinogens that could present serious health risks for machine operators and have inherent waste disposal concerns on the environment. In lessening these adverse effects, the manufacturing industry continually seeks to develop machining techniques incorporating liquid-less (dry) methods or environmentally benign coolants. Air-jet cooling is widely regarded as a viable alternative for liquid coolants in machining processes. This thesis proposes a novel air jet cooling arrangement, and assesses its thermal effectiveness and operational compatibility for specific requirements in metal cutting operation. For tests, steel rods were machined on a standard lathe workbench at selected cutting depth, feed and speed. Type 1040 steel, which is commonly used in automobile industry, was chosen as work piece material. Instead of traditional liquid coolant, a specially designed compressed air jet is used to dissipate heat generation in the cutting zone at the tool tip. The tool tip is presented orthogonally to the work piece to maintain conformity with relevant established cutting tool theories. A special air jet configuration based on a Ranque-Hilsch vortex tube was designed and developed for cooling the cutting zone and tool tip. The tool tip temperatures were measured by installing thermocouples at strategic locations on the tool piece and recorded on a data-logger for a range of cutting depths, feeds and speeds. The cutting power was measured with a power meter attached to the electrical power supply to the lathe. For comparison purposes, tests were also conducted with conventional single-nozzle air jets in place of the vortex-tube jets, using traditional liquid coolant and without any cooling applied to the tool tip. / A thermal vision camera was also deployed for selected tests to ascertain the temperature characteristics at the tool tip. The data was analysed to establish the thermal characteristics at the tool tip with vortex tube air jet, conventional air jet and no air jet cooling. The measured temperatures and cutting data were used to make assessments on cooling efficiency of jets used and surface finish quality of work piece. Estimates of tool life were made from the cutting theory to determine the effectiveness of the cooling systems used in the machining process. It is found that the proposed vortex tube based air jet cooling arrangement provides a highly efficient heat removal mechanism for metal cutting and delivers thermal cooling performance very much comparable to traditional liquid coolants without the inherent chemical exposure risks to machine operators and harmful impact on the environment. With the proposed air jet cooling, the tool life is very much unchanged and the surface finish quality of work piece shows no significant change while savings will realise though lesser dependency on liquid coolant requiring careful disposal and associated costs.

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This master thesis deals with the development of electrophoretic methods for determination of tantalum in recycled coolants used in the production of tantalum capacitors, as well as the separation of tantalum from chemically similar niobium. Developed methods are based on the formation of negatively charged complexes of tantalum and niobium with a number of ligands added to the separation electrolyte, especially tartaric and citric acid and 4-(2-pyridylazo)resorcinol. The separations were performed in a fused silica capillary of the inner diameter of 50 µm and the effective length of 36.5 cm, a negative voltage of -25 kV was applied to the capillary. Using a separation electrolyte containing 0.1 mol·l-1 of tartaric and citric acid at pH = 2, separation of niobium and tantalum was achieved in less than 3 minutes; the absorption spectrometric detection was carried out in the ultraviolet region at a wavelength of 200 nm, the detection limit was 2.8 ppm of tantalum, and the quantification limit was 9.2 ppm of tantalum. Addition of 4-(2-pyridylazo)resorcinol reduced the detection limit to 0.8 ppm of tantalum and the quantification limit to 2.6 ppm of tantalum; the electrolyte contained 0.1 mmol·l-1 of 4-(2-pyridylazo)resorcinol, 10 mmol·l-1 of tartaric acid, 10 mmol·l-1 of citric acid, and 25 mmol·l-1...

This master’s thesis focuses on the heat treatment of the aluminium alloy AlSi7Mg0,6 and also investigates the effects of different coolants usage on its mechanical properties. First part is dedicated to the description of aluminium alloys, their chemical composition, behaviour and mechanical properties with particular attention to the Al-Si-Mg alloys. This part was followed by the summary of commonly used heat treatment of aluminium alloys. The third part is dedicated to the experiment. Castings and test specimens were wax casted at Alucast, s.r.o. company. After annealing, the samples were quickly cooled down in four different coolants and underwent tensile testing. Their mechanical properties (tensile strength, yield point and ductility) were evaluated as well as microstructure. In the last part, the achieved results are presented.