Type of Document Master's Thesis Author Estrada, Miguel Eduardo URN etd-01142008-171414 Title Model-Based Framework For Alloy Electrodeposition Processes Degree Master of Science in Chemical Engineering (M.S.Ch.E.) Department Chemical Engineering Advisory Committee
Advisor Name Title Jose A. Romagnoli Committee Chair Francisco R. Hung Committee Member John Flake Committee Member Keywords
- Parameter Estimation
- Complex Modeling
- Electrochemical Codeposition
- Nanometric Multilayers
Date of Defense 2007-12-03 Availability unrestricted AbstractThe electrodeposition of iron-group alloys has been widely studied due to their interest as materials used for their magnetic and thermo-physical properties. Models such as ternary NiCoFe and quaternary NiCoFeCu multilayer alloys have been previously developed to simulate mass transfer and reaction kinetics. The reactions involved in the models contain kinetic parameters such as rate constants and inverse Tafel slopes which are estimated using trial and error techniques. The previous models are limited to a set of kinetic parameters for each change in concentrations of the electrolyte. Although deposition behaviors such as anomalous codeposition are captured, functionalities to use the models as a tool for interesting deposition schemes are not possible without a single set of kinetic parameters. Therefore, in this project, the use of advanced modeling approaches is investigated to capture the influence of key operating variables affecting the process.
Parameter estimation, based on the maximum likelihood theory, is defined and tested successfully to estimate all kinetic parameters for a wide range of concentrations. The general set of kinetic parameters is fully validated against experimental data and statistical analysis tools are used to evaluate confidence regions. The modeling work is carried out using the gPROMS open modeling software which provides a complete environment for modeling complex systems. All phases of model development are supported by gPROMS which offers a selection of techniques for solving specific problems. Using the open modeling capabilities, the model is developed into a front end application using VBA in excel. This application allows the model to be used by non expert programming users to evaluate electrodeposition behaviors and key variables which play a role into fabricating novel deposition materials. Subsequent to the validation step, the model is used within an optimization framework towards the development of a general method for reproducible production electrodeposition schemes of nanometric multilayers. Successful results are obtained for finding the concentrations and potential needed to deposit fixed compositions of the alloy. Dynamic optimization is tested to develop a time schedule (optimal deposition scheme) aiming at the deposition of a fixed thickness for each multilayer deposition of NiCoFe alloy with Cu.
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