Engineering Commons^™

Intergranular And Pitting Corrosion Mechanisms Of Sensitized Aluminum Alloy Aa5083, Clayton Egleston

Williams Honors College, Honors Research Projects

The motivation and objectives of this project is to examine the mechanisms of intergranular corrosion (IGC) and pitting corrosion of sensitized AA5083. In this regard, different characterization techniques were used, including optical analysis of microstructure, cyclic potentiodynamic polarization with Tafel fitting, electrochemical impedance spectroscopy with electrical equivalent circuit (EEC) fitting, and potentiostatic current transient monitoring. The transition from IGC to pitting corrosion occurs when the grain boundaries become saturated with the β-phase (Mg₂Al₃). It was found that AA5083 becomes more vulnerable to pitting corrosion as the degree of sensitization increases.

Electrochemical Impedance Spectroscopy Analysis Of Corrosion Of Reinforcing Steel In Fly Ash Mortar By Means Of Transmission Line Modeling, Padraig Stack

Williams Honors College, Honors Research Projects

Electrochemical impedance spectroscopy (EIS) is an important non-destructive tool that allows for a deeper understanding of the electrochemical processes and mechanisms occurring in an electrochemical cell. Equivalent electrical circuits (EECs) are used to model the impedance data into electrical components, such as resistors and capacitors, on a circuit. Current potentiostat offers software packages that can analyze the frequency response, but the software only supports “simple” EEC that can be written as fixed electrical components in some combination of series and parallel. Park and Macdonald propose a transmission line model (TLM) that does not use lumped-element models, instead, the values of …

Austenitic, Duplex, And Lean Duplex Stainless Steel Critical Pitting Temperature In Simulated Concrete Environment, Bobby Giebel

Williams Honors College, Honors Research Projects

In this work, the critical pitting temperature (CPT) will be observed for a selection of austenitic (316LN and 24100) and duplex (2205), and lean duplex (2304, 2001) stainless steels in simulated concrete pore solution. To study the influence of temperature on the pitting stability of the stainless steels, three temperatures were tested: 25oC, 45oC, and 65oC for cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS). Electrochemical properties of the interfaces we studied via EIS analysis. Kinetics were studied via CPP testing. To reveal the critical pitting temperature of the stainless steels, cyclic thermammetry was used. Characterization of the pits …

Increasing The Corrosion Protection Of Aisi 1008 Carbon Steel By Surface Treatment With Unmodified And Benzotriazole Modified Sol-Gel Films, Shane Thomas Kelliher

Williams Honors College, Honors Research Projects

The corrosion performance of sol-gel coated AISI 1008 carbon steel was investigated in 3.5 wt% NaCl solutions of pH 7, 9, and 12 using electrochemical measurements. A corrosion inhibitor, benzotriazole (BTA) was added to the sol-gel mixture and tested as a second, modified sol-gel coating. Sol-gel films adhered evenly to metal samples and were characterized by FTIR spectroscopy. Electrochemical Impedance Spectroscopy (EIS) showed an increase in polarization resistance from blank to sol-gel coated samples (600-18,800,000 ohms). Cyclic polarization (CPP) curves showed positive hysteresis loops for blank and unmodified sol-gel coated samples which increased at high pH following the backward potential …

Benefits Of Aluminum: Comparing The Common Materials In The Bar Grating Industry, Joanthan Geiser

Williams Honors College, Honors Research Projects

The main aim of this project is to study the wholistic behavior of the 6xxx series of aluminum for use in the bar grating industry for a waste water treatment environment. This project will study the comparison of certain aluminum 6xxx series alloys to steel, stainless steel, and glass fiber-reinforced plastic. While comparing these materials, it will look at the mechanical properties such as modulus of elasticity, yield strength, and ultimate tensile strength. In addition, the available corrosion test of the 6xxx series aluminum alloys will be examined to find a generalization of the corrosion behavior for this series. A …

The Influence Of Organic Pigments On Coating Properties, Sarah Medeiros

Williams Honors College, Honors Research Projects

Abstract

The purpose of this project was to identify the qualities of two synthesized organic pigments added to a coating. These high-performance pigments were benzodipyrrolidone and benzodifuranone, which are π-conjugated monomers. These pigments were each formulated into two different pigment concentrations and compared with a control that had no pigment. This project is limited by time constraints and the number of variables that can be tested in that time. Performance testing was conducted to evaluate the qualities of these coatings. The results demonstrated that the coatings were reproducible and most tests had results that were equal to or exceeded the …

Pitting Corrosion Of 410 Stainless Steel In Hcl Solutions, Paul D. Krell

Williams Honors College, Honors Research Projects

410 stainless steel (SS) is a material used in HCl services, such as distillation column trays in oil refineries. Unlike other alloys, however, the oil refining industry lacks a good reference for the corrosion rate of 410 SS at the varying HCl concentrations and temperatures the material might experience as trays in crude unit distillation columns. The goal of this project is to fill that knowledge gap. The corrosion behavior of 410 SS in HCl environments of pH 0.50, 1.25, 2.25, 3.25, and 4.25 at temperatures of 38, 52, 79, and 93°C was investigated using several methods. Cyclic potentiodynamic polarization …

Galvanic Corrosion On Monel K-500 And 1018 Carbon Steel Couple, John K. Nnyanzi

Williams Honors College, Honors Research Projects

The purpose of this research project was to evaluate galvanic damage on 1018 Carbon Steel coupled to Monel K-500 at varying rotation speeds on a rotating cylinder electrode in an aerated solution of ASTM artificial seawater. The work in this project is and attempt to study corrosion behavior for a Monel fastener coupled to a Carbon Steel plate. Polarization curves of each material at different rotation speeds were created to predict the corrosion behavior for a galvanic couple of Carbon Steel and Monel. The Potentiodynamic sweeps predict an increase in the corrosion current density for the galvanic couple when then …

Oxidation Resistance Of Nanocrystalline 316l Stainless Steel Processed By High Pressure Torsion, Kevin J. Meisner

Williams Honors College, Honors Research Projects

High Pressure Torsion (HPT) is a materials processing method used to refine the grain size of metallic materials through the application of simultaneous axial and torsional strain. HPT is reported to result in nanocrystalline structure, which the current scientific literature suggests may improve the high temperature oxidation resistance by enhancing diffusion of solutes, particularly Cr, to the surface to form a protective external oxide scale. If oxidation resistance is improved, this possibly allows the use of 316L in oxidizing environments where more expensive alloys are typically used. However, the influence of grain refinement to nanoscale on various properties have been …

The Examination Of Stress Corrosion Cracking In High Strength Carbon Steel Through Combined Mechanical-Electrochemical Testing, Jacob Sines

Williams Honors College, Honors Research Projects

Through the analysis of materials and environments seen in industry a better understanding of the fundamentals behind degradation mechanisms can be observed. The scope of this project was to better understand the fundamentals behind the degradation of high strength pipeline steels in a lab setting to simulate an environment seen in industry. Specifically the degradation mechanisms of high and nearly neutral pH stress corrosion cracking were examined in environments that simulated oil and gas pipelines buried in soil. Experimentation was carried out utilizing X65 carbon steel specimen, a Gamry potentiostat, a CORTEST proof ring, a CORTEST slow strain rate machine, …