Engineering Commons^™

A Comparative Evaluation Of Oxidation And Combustion Phenomena In Ti-6al-4v Exposed To Earth Re-Entry And Arc-Jet Test Environments, Arlene Smith

Open Access Theses & Dissertations

The Ti-6Al-4V alloy is widely used in aerospace applications for its beneficial combination of properties. However, this alloy has high solubility for oxygen and thus a high reactivity. Recovered data contained within the Columbia artifacts suggests that this alloy underwent an accelerated degradation and combustion reaction when exposed to the high enthalpy, low-pressure surroundings experienced during reentry into Earth's atmosphere. Arc-jet testing has provided a simulated aerothermodynamic heating environment to mimic what the spacecraft endured. When the effect of thermal alteration on this alpha-beta phase alloy was investigated during previous studies, optical metallography and microhardness tests revealed inconsistencies between samples …

Infiltration-Controlled Combustion Of Lithium And Magnesium Powders And Reactions Of Lithium With Oxygen And Carbon Dioxide, Kevin Samuel Estala Rodriguez

Open Access Theses & Dissertations

Chemical heat integrated power systems are of great interest for space missions where solar energy, nuclear energy, and batteries are not available or are not practical to use. A new concept of a power system is a metal combustor coupled with a chemical oxygen generator, where the generated oxygen infiltrates through the metal powder or combustion products. The combustion of lithium and magnesium powders under these conditions has not been studied yet. The present work investigates combustion of magnesium powder and stabilized lithium metal powder (SLMP) ignited by a laser inside a closed chamber filled with O2 or CO2. It …

Atomic Layer Deposited Pt/Tio2-Sio2 And Pt/Zro2-Sio2 For Sequential Adsorption And Oxidation Of Vocs, Busuyi O. Adebayo, Han Yu, Ali A. Rownaghi, Xinhua Liang, Fateme Rezaei

Chemical and Biochemical Engineering Faculty Research & Creative Works

In this work, Pt nanoparticles were loaded on SiO₂, TiO₂-thin-film-modified SiO₂ (TiO₂-SiO₂), or ZrO₂-thin-film-modified SiO₂ (ZrO₂-SiO₂) particles and the composites were investigated for sequential adsorption and desorption/catalytic oxidation of benzene. The SiO₂ was prepared via sol–gel method, while TiO₂-SiO₂ and ZrO₂-SiO₂ were synthesized via atomic layer deposition (ALD) thin film coating of TiO₂ or ZrO₂ on SiO₂ particles substrate. In the sequential capture-reaction tests, the materials were first exposed to ca. 500 ppmv benzene …

Degradation Mechanisms Of Zinc-Air Batteries Used In Hearing Aid, Kelly Hunt, Mallorty Bates, Gerard Klint Simon, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

Hearing aid devices are powered by the oxidation of zinc that occurs within zinc-air batteries. Zinc-air batteries have an average discharge time of 7 days. Therefore, hearing-aid devices need frequent battery replacement. In this paper, degradation mechanisms of zinc-air batteries investigated where a competition mechanism between zinc passivation and dendritic formation dictates the battery life. This research included exposure time from none to 9 days and to document dendritic growth with time. Scanning electron microscope images were taken to quantify the damage growth as well energy dispersive X-ray tests were conducted to comment on the composition changes. The results confirmed …

Experimentation Of Abrasion Erosion At High Temperature For Concentrated Solar Power Systems, Tessa Mei-Lin Fong

Boise State University Theses and Dissertations

Concentrated solar power (CSP) is an alternative and sustainable way to produce energy. Studies have shown that running these plants at high temperatures above 700°C can increase the thermal efficiency in heat transfer. Molten salt is usually used as the heat transfer medium but cannot be used due to its low maximum temperature and high freezing point. Running these plants at high temperature brings up the concern of erosion and oxidation. Abrasion erosion occurs through the interaction of particles and material. The goal of this research is to understand material degradation due to abrasion erosion to understand the durability of …

Analyzing The Surface Chemistry Of Ni-Fe Hydroxide Alloy Nanoparticles As Catalysts For The Oxygen Evolution Reaction By X-Ray Photoelectron Spectroscopy Analysis, Lauren B. Shepard

Chemical Engineering Undergraduate Honors Theses

Water electrolysis has been proposed as a renewable source of hydrogen, a possible replacement to harmful fossil fuels. This process can be broken down into two half reactions, the hydrogen evolution reaction and the oxygen evolution reaction. Because the oxygen evolution reaction has slow kinetics and a high overpotential to overcome, a catalyst is needed to speed up the kinetics and ensure faster and more efficient production of molecular hydrogen. The use of Ni-Fe hydroxide alloy nanoparticles as a catalyst has been shown to significantly improve the efficiency of the reaction by decreasing the overpotential, making the process more energy …

The Oxidation Of The Hisimo Cast Irons Alloyed With Cr/Al At 800 °C, Wenhui Zhu, Bruce A. Pint, Yang Huo, Larry Godlewski, Bita Ghaffari, Simon Lekakh, Carlos Engler-Pinto, Mei Li

Materials Science and Engineering Faculty Research & Creative Works

To improve the oxidation resistance of cast iron containing Si and Mo (HiSiMo), 1wt.% Cr and 3wt.% Al were added into the base alloy to improve high temperature oxidation resistance for exhaust manifold applications. Oxidation tests were performed in both dry and wet air (air + 10% H2O) at 800 °C for 1, 10, 24, and 50 h. The mass change and oxide thickness were measured to evaluate the oxidation resistance. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) and transmission electron microscopy (TEM) were employed to characterize the oxidized samples. The results showed that the additions of Al …

Cobalt Ferrite Nano-Composites For The Oxidation Of Phenols In Oil Refinery Wastewater, Amira Mohamed

Theses and Dissertations

Phenolic compounds have the tendency to persist in the environment over a long period making them a main source of concern because of their toxic characteristics towards humans and animals (Bruce et al., 1987). Therefore, existence of phenolic compounds in aquatic environment is unfavourable and as a result, many treatment techniques have been implemented to treat the wastewater produced from petroleum refineries. Petroleum refineries are among the top industries that produces significant quantities of high phenol concentration wastewater. Photo-catalysis is a promising and effective method to treat phenol present in oil refineries effluent. In this study, the photo-catalyst used is …

Effect Of Spallation On Oxidation Kinetics Of Heat-Resistant Cr–Ni Austenitic Steels On Air And Combustion Atmosphere, Simon N. Lekakh, Oleg Neroslavsky, Mei Li, Larry Godlewski, Wenhui Zhu

Materials Science and Engineering Faculty Research & Creative Works

Thin-walled castings made from Cr–Ni austenitic steels offer a combination of light weight of a near-net component with significant high temperature corrosion protection by forming a surface oxide layer. However, above critical service conditions (temperature, atmosphere, thermal cycling), oxidized surface can result in intensive surface degradation due to scale spallation. Scale spallation can decrease the wall thickness which could be detrimental to the in-service life of thin-walled castings. Experiments and stochastic simulations of spallation assisted oxidation were performed with three cast austenitic heat-resistant steels having different Cr–Ni concentrations at temperatures between 900 and 1000 ℃ on air and water vapor …

Oxidative Aging And Fracture Behavior Of Polymers And Composites: Theory, Modeling And Experiments, Shabnam Konica

Dissertations, Master's Theses and Master's Reports

Polymers and their composites (PMC) have emerged as effective alternative materials in structural, aerospace, and automotive industries due to their lightweight and tunable properties compared to metals. However, these materials tend to degrade during their operations in extreme environments. In this work, two extreme conditions are considered: - i) high-temperature oxidative degradation of polymers and polymer-based composites ii) Fracture and damage of polymer-based composites under thermo-mechanical loading.

Polymer oxidation starts when oxygen from the ambient diffuses into the bulk material and initiates chemical reactions to develop a coarse, brittle oxide layer on the exposed surface. The oxidative degradation process is …

The Role Of Microstructure On High-Temperature Oxidation Behavior Of Hafnium Carbide, Jonathan A. Scott, Xiaoqing He, David W. Lipke

Materials Science and Engineering Faculty Research & Creative Works

Microstructure development of the products formed upon oxidation of hafnium carbide (HfCx, x = 0.65, 0.81, or 0.94) at 1300°C and 0.8 mbar oxygen pressure was investigated using Raman spectroscopy, X-ray diffraction, electron microscopy, and electron energy-loss spectroscopy. For all specimens a multilayered oxide scale was observed featuring an outermost porous hafnia layer and an interlayer adjacent to the parent carbide containing hafnia interspersed with carbon. The outermost hafnia features coarse pores presumably formed during initial stages of oxidation to allow rapidly evolving gaseous products to escape from the oxidation front. As the oxidation scale thickens, diffusional resistance results in …

Minimizing Cr-Evaporation From Balance Of Plant Components By Utilizing Cost-Effective Alumina-Forming Austenitic Steels, Lingfeng Zhou

Graduate Theses, Dissertations, and Problem Reports

A solid oxide fuel cell (SOFC) is a clean and efficient energy conversion device. The development of intermediate-temperature SOFCs has made it preferable to use metallic interconnects (MICs) to greatly reduce the cost and significantly increase the efficiency compared to ceramic interconnect materials. However, gaseous chromium species will evaporate from the chromium-containing layer formed on the surface of commonly used MICs and balance of plant (BoP) components. Volatile chromium species have been shown to form solid deposits which poison the cathodes of SOFCs, causing drastic cell performance degradation and thereby limiting commercialization. In order to alleviate the Cr poisoning and …