Materials Science and Engineering Commons^™

Advanced Air Preheater Sealing Systems For Enhanced Efficiency And Reliability In Thermal Power Plants, Pavan Kumar Ravulaparthy

Theses and Dissertations

Global electricity generation still relies heavily on thermal power plants, which consume vast amounts of fuel and emit significant amounts of carbon dioxide. A major but often overlooked source of inefficiency in these plants lies within the rotary regenerative air preheater (RAPH), a critical heat-exchange component where air leakage can exceed 20% in aging units. This leakage increases fuel consumption, parasitic fan power, and CO₂ emissions, while degrading boiler reliability.

This research introduces advanced adaptive sealing systems designed to mitigate these losses by dynamically compensating for rotor eccentricity, thermal distortion, and wear under harsh operating conditions. Brush seals, composed of …

Laser Ablation-Induced Corrosion Resistance For Molten Salt Equipment Materials Evaluated Utilizing Electrochemical And Spectroscopic Analysis, Peggy Milota

Theses and Dissertations

Advanced reactors and used nuclear fuel separation (i.e. pyroprocessing technology) utilize high temperature salt as a thermal storage medium as well as an ionic solution for electrochemical processes. The use of these aggressive molten chloride and fluoride mediums requires specific materials or additional system alterations to extend the lifetime and structural integrity of equipment due to corrosion. Some materials, in the presence of inherently impure salt, will corrode and form oxide films in a specific formation that decreases corrosion rate by electrochemically and physically preventing elemental movement to the material surface. This is referred to as a passivation layer. However, …

Exploration And Synthesis Of Tin Intermetallic Single Crystals, Jared L. Shortt

Graduate Theses/Dissertations

This thesis presents the synthesis and characterization of two tin-based intermetallic compounds: Mn₄.₁₂Sn and Ni₆Sn₈Ge₀.₄₇. Single crystals were grown using a high-temperature self-flux method, allowing for the formation of phase-pure samples suitable for structural and physical property analysis. The crystalline phases were identified and refined using powder and single-crystal X-ray diffraction (XRD), while scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDS) was employed to verify stoichiometry and homogeneity. Magnetization measurements performed using a superconducting quantum interference device (SQUID) magnetometer revealed distinct magnetic behavior in the manganese-rich compound, while the nickel-based compound was explored for potential magnetic features arising from …

Semi-Quantitative Elemental Imaging Of Corrosion Products From Bioabsorbable Mg Vascular Implants In Vivo, Weilue He, Keith W. Macrenaris, Adam Griebel, Maria P. Kwesiga, Erico Freitas, Amani Gillette, Jeremy Schaffer, Thomas V. O'Halloran, Roger J. Guillory Ii

Michigan Tech Publications

While metal materials historically have served as permanent implants and were designed to avoid degradation, next generation bioabsorbable metals for medical devices such as vascular stents are under development, which would elute metal ions and corrosion byproducts into tissues. The fate of these eluted products and their local distribution in vascular tissue largely under studied. In this study, we employ a high spatial resolution spectrometric imaging modality, laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) to map the metal distribution, (herein refered to as laser ablation mapping, or LAM) from Mg alloys within the mouse vascular system and approximate …

Linking Molecular Structure Evolution To Mechanical Degradation During Environmental Aging In Conventional And Recyclable Epoxy Systems, Ben T. Jewell

Dissertations, Master's Theses and Master's Reports

The long-term performance of polymeric materials in extreme environments is governed by complex chemical and physical aging processes that alter their molecular structure and mechanical integrity. Conventional thermoset epoxies, while widely used in structural applications, are particularly susceptible to oxidative degradation at elevated temperatures, leading to embrittlement and loss of structural integrity. In the first part of this work, diffusion-limited oxidation (DLO) in a bulk structural epoxy was systematically investigated to establish the link between heterogeneous microstructural evolution and macroscopic mechanical degradation. High-temperature oxidation experiments were conducted in a controlled environmental chamber, and the resulting chemical, thermal, and mechanical changes …

Degradation Of Polymers And Polymer Composites In Extreme Environments, Ben T. Jewell

Dissertations, Master's Theses and Master's Reports

Polymeric materials are widely used in engineering applications due to their high strength-to-weight ratio, easy manufacturability, and cost-effectiveness. When incorporated into composites, they provide further performance enhancements, enabling use in demanding structural applications. However, long-term exposure to harsh environments including elevated temperatures, UV radiation, harsh chemicals, and radiation, can drive degradation processes that alter the material’s network structure, and in turn, degrade its mechanical performance. Exposure to thermo-oxidative conditions is one of the most common environments driving polymer degradation, leading to chain scission and crosslinking events, with the resulting oxidative products causing discoloration, reduced ductility, and changes in glass transition …

Development Of Bio-Based Coating Materials For Environmentally Friendly Controlled-Release Nitrogen Fertilizer Applications, Anne Carolyne Mendonca Cidreira

Electronic Theses and Dissertations

No abstract provided.

A Pyrrole Modified 3,4-Propylenedioxythiophene Conjugated Polymer As Hole Transport Layer For Efficient And Stable Perovskite Solar Cells, Yuanhao Tang, Ke Ma, Wenhao Shao, Yoon Ho Lee, Ashkan Abtahi, Jiaonan Sun, Hanjun Yang, Aidan H. Coffey, Harindi R. Atapattu, Mustafa Ahmed, Qixuan Hu, Wenzhan Xu, Raunak Dani, Limei Wang, Chenhui Zhu, Kenneth R. Graham, Jianguo Mei, Letian Dou

Chemical and Materials Engineering Faculty Publications

Despite the outstanding electric properties and cost-effectiveness of poly- (3,4-ethylenedioxythiophene) (PEDOT) and its derivatives, their performance as hole transport layer (HTL) materials in conventional perovskite solar cells (PSCs) has lagged behind that of widely used spirobifluorene-based molecules or poly(triaryl amine). This gap is mainly from their poor solubility and energy alignment mismatch. In this work, the design and synthesis of a pyrrole-modified HTL (PPr) based on 3,4-propylenedioxythiophene (ProDOT) are presented for efficient and stable PSCs. As a result of the superior defects passivation ability, excellent contact with perovskite, enhanced hole extraction, and high hydrophobicity, the unencapsulated PPr-based PSCs showed the …

Analysis Of Tar And Oil Derived From Pyrolysis And Copyrolysis Of Waste Plastics And Biomass, Anitha Shankaralinge Gowda, Dimitrios Karadimas, Jeffrey Seay

Chemical and Materials Engineering Faculty Publications

Pyrolysis has been proposed as a potential technology for managing the growing volume of plastic waste generated worldwide. Co-pyrolysis of plastic waste with biomass is a promising technology for generating fuel and chemical products. However, this process generates tar as a waste product. The chemical properties of this tar have yet to be thoroughly analyzed. This study presents the results of gas chromatography–mass spectrometry (GC–MS), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) of oil and tar obtained from the pyrolysis of pure plastics including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), polystyrene (PS), and plastic-biomass mixtures. GC–MS analysis …

Membrane Filtration Of Nanoscale Biomaterials: Model System And Membrane Performance Evaluation For Aav2 Viral Vector Clarification And Recovery, Mara Leach, Kearstin Edmonds, Emily Ingram, Rebecca E. Dutch, Ranil Wickramasinghe, Malgorzata Chwatko, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

The growing demand for viral vectors as nanoscale therapeutic agents in gene therapy necessitates efficient and scalable purification methods. This study examined the role of nanoscale biomaterials in optimizing viral vector clarification through a model system mimicking real AAV2 crude harvest material. Using lysed HEK293 cells and silica nanoparticles (20 nm) as surrogates for AAV2 crude harvest, we evaluated primary (depth filters) and secondary (membrane-based) filtration processes under different process parameters and solution conditions. These filtration systems were then assessed for their ability to recover nanoscale viral vectors while reducing DNA (without the need for endonuclease treatment), protein, and turbidity. …

Fundamental And Application Of Co-Assembly Of Peptides And Proteins: Experiment And Computation, Newton A. Ihoeghian, Qing Shao

Chemical and Materials Engineering Faculty Publications

Peptides and proteins can co-assemble into various nanostructures based on complementary non-covalent interactions such as electrostatic forces, hydrogen bonding, and hydrophobic associations. These co-assemblies create a design space of functional materials for a wide spectrum of energy, environmental, and biomedical applications. This review focuses on the fundamentals and applications of three co-assembling systems: ultra-short peptides, peptides, and proteins. We will present and discuss experimental studies demonstrating applications in drug delivery, tissue engineering, and biomaterials development. We will also discuss the contribution of computational research, including molecular dynamics simulations and machine learning, to enhance our understanding of assembly mechanisms. Integrating experimental …

Accelerated Aging System For Pinniped Tags, Sean Shermer, Nathan Vasquez, Deekshitha Garige

Undergraduate Scholarship

This project focused on the design of an accelerated aging system intended to evaluate the durability of pinniped identification tags used in marine mammal research. The system was developed in collaboration with the Cal Poly Humboldt Marine Lab and NOAA, under the guidance of Dr. Dawn Goley, to address the limitations of field based durability testing, which is slow, inconsistent, and difficult to reproduce. The primary objective was to create a repeatable laboratory testing framework capable of simulating multiple environmental stressors experienced by pinniped tags. This includes the accelerated tests of UV radiation, mechanical abrasion, temperature cycling and biological fouling. …

Side-By-Side Evaluation Of The Outgassing Rate And Ultimate Pressure Achieved Inside Tubes Made Of Low-Carbon And Stainless Steel, Aiman H. Al-Allaq, Md Abdullah Mamun, Matt Poelker, Abdelmageed Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

The hydrogen outgassing rate of a vacuum chamber made of AISI 1020 low-carbon steel was found to be notably smaller than a similar chamber made of AISI 316L stainless steel following heat treatment at 150 degrees C. When the chambers were baked at 400 degrees C, the outgassing rate of the 1020 low-carbon steel chamber was approximately 2000 times smaller than that of the 316L stainless-steel chamber. After quantifying hydrogen outgassing rates, vacuum chambers made of 1020 low-carbon steel and 316L stainless steel were heated for a prescribed duration and then pumped with an ion pump and nonevaporable getter pump …

Rheology Of Alumina Suspensions Subjected To Alternating Current Electric Fields For Freeze-Casting, Sivakumar Chithamallu, Ruksana Baby, Jacob L. Jones, Dipankar Ghosh

Mechanical & Aerospace Engineering Faculty Publications

Alternating current (AC) electric field can extrinsically tune freeze‐cast microstructure, originating from field‐induced increase in viscosity of ceramic suspensions. However, the changes that occur in a ceramic suspension and rheological behavior, ultimately affecting freeze‐cast microstructure, are not well understood. Moreover, the effects of AC electrokinetic forces and temperature on viscosity need to be decoupled. The viscosity and temperature of ceramic suspensions subjected to AC field and direct heating were measured, revealing that the increase in viscosity is due to AC dielectrophoretic forces rather than field‐induced heating of suspension. The shear thinning behavior of suspensions characterized using a power‐law model reveals …

Outgassing Measurements Of Bare And Magnetite-Coated Low-Carbon Steel Vacuum Chambers, Aiman H. Al-Allaq, Md Abdullah Mamun, Matt Poelker, Abdelmageed Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

The outgassing properties of bare and magnetite-coated AISI 1020 low-carbon steel vacuum chambers were evaluated to establish material selection criteria for extreme high vacuum applications, namely, to explore the possibility of using these materials to build next-generation spin-polarized photoelectron guns. Water outgassing measurements using the throughput method revealed that the magnetite-coated chamber exhibited five times lower outgassing at room temperature prior to baking, but this advantage disappears after 80 °C baking. Hydrogen outgassing measurements demonstrated significant differences after intensive heat treatment: the bare low-carbon steel vacuum chamber achieved a specific outgassing rate of 9.6 × 10⁻¹⁶ Torr L s …

Machine Learning Modeling For Hydrolysis Recycling Of Pet Waste, Jie Li, Lanjia Pan, Hossein Abedsoltan, Hailong Wang, Taiyang Liu, Xiangzhou Yuan, Yong Sik Ok, Yin Wang

Chemical and Biochemical Engineering Faculty Research & Creative Works

The hydrolysis of polyethylene terephthalate (PET) into terephthalic acid (TPA) can efficiently recycle waste PET, but achieving high conversion efficiency through smart reaction design remains challenging. To develop a robust and accurate machine learning (ML) model for the in-depth understanding and intelligent design of PET hydrolysis, we compiled a new dataset comprising 942 data points and comprehensive information of 44 variables involved in heating type, acid/base catalyst (ABC), organic solvent (OS), co-solvent (CS), phase transfer catalyst (PTC), and operational conditions. The developed Neural Network model demonstrated the best performance in predicting PET conversion, with a testing determination coefficient (R^{2 …}

Effect Of Bioactive Glass On Pxdda / Pxdda-Co-Pla Nanocomposite For Hard Tissue Reconstruction: Synthesis And Characterization, Ehsan Vafa, Lobat Tayebi, Fatemeh Azizli, Somayeh Parham, Katayoon Rezaeeparto, Sedigheh Azadi, Ali Mohammad Amani, Mohammad Javad Azizli, Hesam Kamyab, Shreeshivadasan Chelliapan, Saravanan Rajendran

Electrical & Computer Engineering Faculty Publications

Newer bone graft materials face various challenges in achieving optimal mechanical strength, bioactivity, and antibacterial action simultaneously, which can result in suboptimal regeneration outcomes and increased infection risks In the present study, we developed a novel nanocomposite of poly (xylitol-co-dodecanedioic acid) (PXDDA) and poly (lactic acid) (PLA) with 1-10 wt% incorporation of bioactive glass (BG), utilizing a a PXDDAco-PLA compatibilizer for maintaining homogeneity. Extensive characterization techniques including, Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauere Emmette Teller (BET), Proton Nuclear Magnetic Resonance (¹H NMR) and contact angle measurements, revealed that the addition …

A Comparison Of Microcrystal Electron Diffraction And X-Ray Powder Diffraction For The Structural Analysis Of Metal-Organic Frameworks, Erik Biehler, Silvana Pagola, Daniel Stam, Johannes Merkelbach, Christian Jandl, Tarek M. Abdel-Fattah

Chemistry & Biochemistry Faculty Publications

This study successfully implemented microcrystal electron diffraction (microED) and X-ray powder diffraction (XRPD) for the crystal structure determination of a new phase, TAF-CNU-1, Ni(C₈H₄O₄)·3H₂O, solved by microED from single microcrystals in the powder and refined at the kinematic and dynamic electron diffraction theory levels. This nickel metal–organic framework (MOF), together with its cobalt and manganese analogues with formula M (C₈H₄O₄)·2H₂O with M = Mn ^II or Co^II, were synthesized in aqueous media as one-pot preparations from the corresponding hydrated metal chlorides and sodium terephthalate, as a promising `green' synthetic route to moisture-stable MOFs. The crystal structures of the …

Metathesis Or Isomerization: Counteranion Directed Reactivity Of Grubbs I, Paul D. Miller, Joe B. Calkins, Craig A. Bayse, Trandon A. Bender

Chemistry & Biochemistry Faculty Publications

Catalytic isomerization of alkenes has garnered interest for many years, but there are remaining challenges when it comes to thermodynamic selectivity and uncontrolled isomerization. Nonbiased substrates, be it sterically or thermodynamically, remain challenging for many catalysts, with a few examples available in the more modern literature. Herein, we present the controlled isomerization of linear alkenes with a cocatalytic mixture of commercially available catalyst and reagents: Grubbs I, tris(pentafluorophenyl)borane, and triethylsilane. DFT calculations indicate that an observed alkylidyne hydride intermediate is in rapid equilibrium with an alkylidene that binds the alkene substrate. This combination results in a pi-acidic metal and a …

Amphiphilic Tripodal Metalloligands: Synthesis, Coordination Chemistry And Preliminary Catalysis, Austin W. Medley, Paul D. Miller, Craig A. Bayse, Robert D. Pike, Trandon A. Bender

Chemistry & Biochemistry Faculty Publications

Triscatecholate binding has been widely studied in the context of biological systems, supramolecular chemistry, and weak aggregate interactions. However, the utilization of the triscatecholate binding motif for the preparation of metalloligands remains unexplored. Herein, we report the synthesis, structural characterization, and functional studies of a triscatecholate ligand with an appended pyridyl residue as a candidate for such applications. Our findings reveal that the selective formation of cis-triscatecholate-based metalloligands is influenced by electronic effects on the catecholate anions, enabling the targeted synthesis of Al(III), Ga(III), and In(III) triscatecholate metalloligands capable of binding Zn(II) and Ru(II) at the appended pyridyl moiety for …