Matching Items (3)
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- All Subjects: aluminum
- Creators: Solanki, Kiran
- Creators: Chan, Candace
- Creators: Votroubek, Edward Daniel
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
- Status: Published
Description
Surface Mechanical Attrition Treatment (SMAT) is a process used to coat metallic alloy surfaces with a nanocrystallized layer via mechanical abrasion. SMAT has garnered a significant amount of interest from the scientific community as a surface treatment technique due to the ability of this fine grain top layer to provide several benefits to its constituent alloy, namely significantly higher hardness, fatigue strength, and most pertinently, greatly improved corrosion resistance. Emerging research suggests that SMAT can also be used to apply powder coatings onto target substrates. A given substrate can be installed in a ball mill, where stainless steel balls coated with pure elemental powder deliver sustained impact onto the substrate, embedding the powders onto its surface. This paper will explore the process of coating aluminum 7075 coating with chromium powder via SMAT, and the effects doing so will have on the corrosion resistance properties of the aluminum 7075. Traditionally, high-strength alloys have been treated with chromium via the process of electroplating, where the alloys are subjected to a hexavalent chromium plating procedure that is known to risk releasing toxic carcinogens into the environment. Coating these alloys with SMAT could minimize such negative externalities, while yielding benefits unique to the SMAT coating process itself. Baseline corrosion testing reveals that the corrosion resistance properties of the aluminum 7075 improved marginally when exposed to SMAT without the addition of any chromium powder. A literature review conducted in this paper of select studies on SMAT coating also demonstrates that material properties intrinsic to aluminum 7075 and pure chromium powder, as well as interaction effects occurring between aluminum and chromium when subjected to mechanical alloying, could enable the SMAT coating of aluminum 7075 with chromium to result in greatly enhanced corrosion resistance properties. While this was not accomplished within the duration of the Honors Project due to logistical difficulties brought forth by the COVID-19 epidemic, the baseline corrosion testing performed, as well as the literature review of studies directly relevant to the matter, should hopefully provide some information of value in any future exploration of the topic.
ContributorsMcManus, Matthew Harada (Co-author, Co-author) / Solanki, Kiran (Thesis director) / Beura, Vikrant (Committee member) / School of Politics and Global Studies (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
In 2015, the United States consumed about 140.43 billion gallons of gasoline, resulting in the emission of over 1 billion metric tons of carbon dioxide, according to the U.S. Energy Information Administration. Despite continued efforts to develop more efficient engines and cleaner fuels, a major barrier to reducing energy consumption and CO2 production is the mass of the vehicle. Replacing traditional automotive materials such as iron and steel with lighter-weight materials is a big step toward improving fuel economy. Magnesium has great potential for use in the automotive industry because of its low density, about 78% less than the density of steel, and high strength-to-weight ratio. Using cast magnesium instead of steel can reduce the overall weight of a vehicle, improving performance and increasing fuel efficiency. However, magnesium’s high susceptibility to corrosion limits its feasibility as a substitute for traditional materials.
This project aimed to understand the effects of composition and phase distribution on the corrosion behavior of magnesium-aluminum (Mg-Al) alloys in an ionic liquid electrolyte. The purpose of studying corrosion in nonaqueous ILs is to determine the anodic dissolution behaviors of the alloy phases without the interference of side reactions that occur in aqueous electrolytes, such as di-oxygen or water reduction. Three commercial Mg-Al alloys were studied: AZ91D (9% Al), AM60 (6% Al), and AZ31B (3% Al). An annealed alloy containing solid-solution α-phase Mg-Al with 5 at% aluminum content (Mg5Al) was also used. The ionic liquid chosen for this project was 1:2 molar ratio choline-chloride:urea (cc-urea), a deep eutectic solvent. After potentiostatic corrosion in cc-urea, the magnesium alloys were found to form a high surface area porous morphology as corrosion duration increased. This morphology consists of aluminum-rich ridges formed by Al nanowires surrounding an aluminum-poor base area, but with an overall increase in surface Al composition, indicating selective dealloying of the Mg in cc-urea and redistribution of the Al on the surface. Further work will focus on the development of hydrophobic coatings using ionic liquids.
This project aimed to understand the effects of composition and phase distribution on the corrosion behavior of magnesium-aluminum (Mg-Al) alloys in an ionic liquid electrolyte. The purpose of studying corrosion in nonaqueous ILs is to determine the anodic dissolution behaviors of the alloy phases without the interference of side reactions that occur in aqueous electrolytes, such as di-oxygen or water reduction. Three commercial Mg-Al alloys were studied: AZ91D (9% Al), AM60 (6% Al), and AZ31B (3% Al). An annealed alloy containing solid-solution α-phase Mg-Al with 5 at% aluminum content (Mg5Al) was also used. The ionic liquid chosen for this project was 1:2 molar ratio choline-chloride:urea (cc-urea), a deep eutectic solvent. After potentiostatic corrosion in cc-urea, the magnesium alloys were found to form a high surface area porous morphology as corrosion duration increased. This morphology consists of aluminum-rich ridges formed by Al nanowires surrounding an aluminum-poor base area, but with an overall increase in surface Al composition, indicating selective dealloying of the Mg in cc-urea and redistribution of the Al on the surface. Further work will focus on the development of hydrophobic coatings using ionic liquids.
ContributorsWeiss, Anna Caroline (Author) / Sieradzki, Karl (Thesis director) / Chan, Candace (Committee member) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
In real world applications, materials undergo a simultaneous combination of tension, compression, and torsion as a result of high velocity impact. The split Hopkinson pressure bar (SHPB) is an effective tool for analyzing stress-strain response of materials at high strain rates but currently little can be done to produce a synchronized combination of these varying impacts. This research focuses on fabricating a flange which will be mounted on the incident bar of a SHPB and struck perpendicularly by a pneumatically driven striker thus allowing for torsion without interfering with the simultaneous compression or tension. Analytical calculations are done to determine size specifications of the flange to protect against yielding or failure. Based on these results and other design considerations, the flange and a complementary incident bar are created. Timing can then be established such that the waves impact the specimen at the same time causing simultaneous loading of a specimen. This thesis allows research at Arizona State University to individually incorporate all uniaxial deformation modes (tension, compression, and torsion) at high strain rates as well as combining either of the first two modes with torsion. Introduction of torsion will expand the testing capabilities of the SHPB at ASU and allow for more in depth analysis of the mechanical behavior of materials under impact loading. Combining torsion with tension or compression will promote analysis of a material's adherence to the Von Mises failure criterion. This greater understanding of material behavior can be implemented into models and simulations thereby improving the accuracy with which engineers can design new structures.
ContributorsVotroubek, Edward Daniel (Author) / Solanki, Kiran (Thesis director) / Oswald, Jay (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05