Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Engineering
Fundamental Study Of The Role Of Cathode Structure On Zinc Electrowinning, Horacio M. Aros
Fundamental Study Of The Role Of Cathode Structure On Zinc Electrowinning, Horacio M. Aros
Doctoral Dissertations
"The influence of cathode macromorphology on the current efficiency of zinc electrowinning was determined.
The studies have shown that surface roughness affects current efficiency during zinc electrowinning, particularly when the electrolyte contains impurities such as nickel and antimony. Current efficiency does not change with surface roughness as long as the electrolyte is sufficiently pure.
Zinc deposited on smooth zinc cathodes tends to retain a more favorable structure and macromorphology, which is less sensitive to the effects caused by antimony and nickel. Glue helps to counteract the effect of the impurities; however, its presence in the electrolyte at certain combinations with …
Studies Of Defect Structure And Oxidation-Reduction Behavior Of Undoped Lamno₃, Sr-Doped Lamno₃ And Mg-Doped Lamno₃, Jen-Ho Kuo
Doctoral Dissertations
"Undoped LaMnO₃, Sr-doped LaMnO₃ and Mg-doped LaMnO₃ showed reversible oxidation-reduction behavior. These perovskites can be excess, stoichiometric or deficient in oxygen content depending on the specific conditions. Under very reducing conditions these oxides will decompose into new phases. Phase stabilities for these oxides were determined. The results showed that both Sr and Mg doping caused the LaMnO₃ to dissociate at higher oxygen activities than for undoped LaMnO₃.
Defect models were proposed to interpret the TG results, in which metal vacancies are assumed for the oxygen excess condition and oxygen vacancies are assumed for the oxygen deficient condition. Thermodynamic properties were …
Bubble Formation, Movement And Distortion In Viscous Glass, Simon Cheng-Ping Wang
Bubble Formation, Movement And Distortion In Viscous Glass, Simon Cheng-Ping Wang
Doctoral Dissertations
"A study of bubble formation, movement and distortion in viscous glass is described. A glass rod containing an irregularly shaped hole is heated to a temperature at where the glass viscosity is low enough to let the hole form a spherical bubble. Spheration occurs as the bubble moves upward in the glass rod. At the proper time, the rising bubble is decelerated and brought to a stop by increasing the glass viscosity by slowly reducing the temperature. The entrapped bubble is then cut from the glass rod and heated again, if necessary, to a lower temperature, to reduce distortion of …