No description available.

Thesis (B.S.)--Virginia Polytechnic Institute, 1944. / Includes bibliographical references (leaves 40-43). Also available via the Internet.

Thesis (Ph. D.)--Ohio State University, 1924. / Autobiography. Autographed from type-written copy.

Thesis (Ph. D.)--Washington University, 1920. / Vita. Slightly abridged from Iron and Steel Institute, Carnegie scholarship memoirs, vol. VII (1916) p. 232-298.

Thesis (Ph. D.)--Ohio State University, 1924. / Autobiography. Autographed from type-written copy.

Thesis (Ph. D.)--Washington University, 1920. / Vita. Slightly abridged from Iron and Steel Institute, Carnegie scholarship memoirs, vol. VII (1916) p. 232-298.

M.Ing. (Civil Engineering) / Please refer to full text to view abstract

No abstract / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Crevice corrosion experiments have been conducted on Inconel 600 and Inconel 625 exposed to two principle test solutions of 1 M NaCl and 1 M NaCl + 0.01 M Na₂S₂0₃ (Sodium Thiosulphate) at three temperatures, 22°C, 55 °C and 80°C. The crevice corrosion tests were performed in a corrosion cell which was constructed from PTFE (Polytetrafluoroethylene, Teflon) and Pyrex glass. Features of the cell included the utilization of an artificial Teflon-metal crevice and provisions to monitor crevice corrosion current, active crevice corrosion potential and active crevice pH. Additional experiments included potentiodynamic anodic polarization tests on pure Ni, Alloy 600, and Alloy 625 in bulk solution environments and in simulated crevice solutions. Crevice corrosion morphology and compositional analysis of the corrosion products was studied using a scanning electron microscope equipped with an X-ray energy dispersive spectroscopy (EDS) system. Results show that crevice corrosion rates increase with increasing temperature for Alloy 600 in both principle test solutions. X-ray EDS analysis indicated that an insoluble nickel sulphide corrosion product formed on Alloy 600 in a solution of 1 M NaCl + 0.01 M Na₂S₂0₃. For the Alloy 600, in a solution of 1 M NaCl + 0.01 M Na₂S₂0₃, initiation times were significantly reduced and crevice corrosion propagation rates enhanced, as compared to Alloy 600 in 1 M NaCl. The decrease in initiation times has been attributed to the destabilizing nature of the S₂O₃⁻² species on the passive oxide film. Enhanced propagation rates have been attributed to the presence of H₂S in the crevice solution and the formation of an adsorbed species Ni(H₂S)ads which enhances the anodic dissolution reaction. The H₂S in the active crevice solution originated from the thermodynamically favoured electrochemical reduction of the S₂0₃⁻² species in the active crevice solution. Experiments on Alloy 625, which is alloyed with molybdenum, (Mo), show that it was virtually immune to crevice corrosion as compared to Alloy 600 which is not alloyed with Mo. The resistance of Alloy 625 to crevice corrosion initiation has been attributed to the stabilizing nature of MoO₂ in the passive oxide film. For an actively corroding system, the formation of the molybdate species MoO₄⁻² may act as an anodic inhibitor and effectively enhance the repassivation of the passive film. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, Johannesburg, 2019 / Premature deterioration of reinforced concrete railway bridges before and after repair is a serious concern as it is costly and poses a major risk on safety and performance. Reinforced concrete railway bridges in aggressive environments (near the sea) face the risk of ingress of corrosion agents (oxygen, moisture and chlorides) into the concrete to the reinforcing steel. Although, corrosion of the reinforcing steel is not the only cause of structural deficiencies in railway bridges, it is a significant contributor to deterioration and therefore of major concern. In order to guide the selection of a suitable repair option, one repair material from each category (patch repair mortars, barrier systems, electrochemical methods and corrosion inhibitors) was investigated. The effectiveness of selection was assessed by employing electrochemical techniques to quantify the performance of each selected repair material in stifling chlorideinduced corrosion in reinforced concrete. This study focuses on the evaluation of selected repair materials for chloride-induced corrosion in reinforced concrete using 100 x 100 x 500 mm long beam specimens. The four selected repairs were applied to the reinforced concrete beams after a period of 200 days after casting. The beams had a constant concrete cover to reinforcing steel of 20mm. The beam specimens were casted using admixed chlorides into the mix and were subjected to a cycle of 3 days wetting (with 5% NaCl solution) and 4 days drying. The beam specimens were monitored for half-cell potential (Cu/CuSO4), corrosion rate (coulostatic technique) and concrete resistivity (Wenner probe technique). Results indicate that the selected repair materials in this study had varied influences on the halfcell potential and corrosion rate values. The patch repair material replaced the concrete cover with a more durable material, confirmed from the Durability Index (DI) tests conducted. The resistivity of the repair mortar was measured to be higher than the concrete. Due to the replacement of the concrete cover, the corrosion rate values reduced when compared to the control reinforced beam specimens. However, the half-cell potential values indicated the probability of corrosion is still high after application. The barrier method, applied a silane-based sealer on the reinforced concrete beams. The resistivity of the concrete increased after application of the barrier method. The corrosion rates after application of the barrier method was lower than the corrosion rates of the control reinforced concrete beams. The half-cell potential results indicated the corrosion risk is still high after application of the barrier method. The electrochemical repair was the only repair material that showed more negative potentials than the control beams and corrosion rates were significantly higher than all the other repair methods after application. The reason for this can be attributed to the zinc anode dominating the potential and corrosion rate values. Therefore, no conclusion can be made on the corrosion condition of the reinforcing steel. Alternative methods should be employed in determining the effectiveness of sacrificial anode repairs. / PH2020