Development of a Novel, Cost-Effective, Open-Source Flow-type Electrochemical Microcell for Localized Corrosion Analysis using Additive Manufacturing Technology
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Authors
Summers, Kodi Lee
Issue Date
2022
Type
Dissertation
Language
Keywords
3D-printed , additive manufacturing , electrochemistry , flow cell , localized , microcell
Alternative Title
Abstract
The ever-present requirement for advanced materials that can meet the demands of current and future technologies remains a significant driving force for the development and utilization of advance characterization techniques. Materials that can withstand corrosive environments can not only improve efficiencies of various processes such as energy production and manufacturing, but they can also reduce waste by increasing the lifetime of components. One of the most difficult forms of corrosion to predict and plan for is localized corrosion. While uniform corrosion occurs at a predictable rate, localized corrosion can lead to catastrophic failure with little notice. Due to localized corrosion being specific to the material and the environment to which it is exposed, there is a significant amount of research to understand and develop models that can help to predict and prevent localized corrosion.Proper characterization of materials for the study of localized corrosion has resulted in a need for enhanced capabilities to perform specific types of analyses. Due to the localized nature, characterization techniques must be able to isolate the areas of interest from a bulk material/environment interaction. One of the methods for performing this type of analysis is to use micro-electrochemical cells. Micro-electrochemical cells encompass a variety of apparatus that emerged from the need to perform electrochemical studies on small areas. The application of microcells has evolved and expanded over time to a variety of fields which has led to the development of three fundamental types of micro-electrochemical cells, with each type designed to fulfill different needs. The microcell was specifically designed to provide a reproducible analysis area, the droplet cell has the ability to continuously scan a sample surface, and the flow cell can be used for high current density electrochemical studies. Each type of micro-electrochemical cell has its unique characteristics that need to be considered prior to use. This research explores all three cell types and focuses on the use of microcells. A comparative analysis of the three different cell types and their advantages and disadvantages will be discussed. Research and development of these micro-electrochemical cell types shown herein provide insight into these advantages and disadvantages from cell construction to operation. The design, fabrication, and testing of a droplet cell, microcell, and flow-type microcell were performed using glass capillaries to understand the operating characteristics of the cells. The use of glass capillaries to create all three cell types resulted in imprecise and inconsistent analysis areas isolated by tips that were extremely fragile and labor intensive to construct. While the glass capillary-based cells were capable of performing electrochemical analysis with an analysis diameter of 86 µm, the disadvantages of using glass capillaries outweighed the benefits resulting in the development of a more robust and practical cell. This dissertation presents the development and successful implementation of a 3D-printed flow-type microcell with spatial resolution of <10 µm in diameter. Verification and demonstration of the 3D-printed flow cell using a high-purity copper plate confirmed comparable performance to traditional bulk flat cell analysis that use larger (1cm2) samples. Additionally, operation of the 3D-printed flow cell was demonstrated by analysis of a variety of samples including a compositionally-graded high-entropy alloy that exhibited differential corrosion behavior along the axis of the composition gradient. A significant achievement of this work is the development and feasibility testing of a 3D-printed flow-type electrochemical microcell with an analysis resolution of less than 10 µm. The ultra-high-resolution 3D-printed flow-type electrochemical microcell is demonstrated and validated by comparison of electrochemical response to similar analysis performed at 100 µm and 1.12 cm diameter analysis areas. The demonstrated feasibility of a sub 10 µm 3D-printed microcell marks a significant departure from previous works using 3D-printed microcells and towards analysis regimes traditional reserved for glass capillary-based cells.