Materials Science and Engineering Commons^™

Strengthening Of 7175 Aluminum Alloy Through Multi-Step Aging Process, Colin E. Masterson, Ryland W. Jolliffe

Materials Engineering

7175 is a heat-treatable aluminum alloy commonly used in aerospace forgings. This alloy is aged with a multi-step heat treatment. This treatment must balance strength with stress corrosion cracking resistance through a degree of overaging. The team was tasked by Weber Metals to increase the strength of this treatment without sacrificing stress corrosion cracking resistance. Both two-step and retrogression and reaging treatments were tested in experiments to find a heat treatment that could increase the yield and tensile strength by 1-2 ksi while maintaining a minimum electrochemical conductivity equivalence of 38% relative to copper. Two-step aging is the more conventional …

Pressure Driven Desalination Membranes: Lyotropic Liquid Crystals Containing Single Walled Carbon, Matteo A. Del Giudice, Samantha Castillo Merigold

Materials Engineering

This project presents a potential alternative desalination technique that utilizes the ion rejection properties of single walled carbon nanotubes dispersed in a lyotropic liquid crystal (LLC) matrix. Previous research has pointed to the polymerizable surfactant methacryloxy ethyl hexadecyl dimethyl ammonium bromide (C16MA) having capabilities of filtering molecular components smaller than a nanometer, when oriented in cylindrical micelles. SWCNTs were dispersed in deionized water by probe sonication and addition of surfactant cetyltrimethylammonium bromide (CTAB) due to SWCNTs’ hydrophobic properties. Membranes were produced containing 55wt% C16MA, 37wt% DI water, 0.1wt% with respect to the monomer (WRM) SWCNTs, 1.9 wt% WRM 2,2-dimethoxy-2-phenylacetophenone (photointiator), …

Quantum Transport Of The 2d Surface State In A Nonsymmorphic Semimetal, Xue Liu, Jin Hu, Jiang Wei, Chunlei Yue, Sergey V. Erohin, Yanglin Zhu, Abin Joshy, Jinyu Liu, Ana M. Sanchez, David Graf, Pavel B. Sorokin, Zinqiang Mao

Physics Faculty Publications and Presentations

In a topological semimetal with Dirac or Weyl points, the bulk-boundary correspondence principle predicts a gapless edge mode if the essential symmetry is still preserved at the surface. The detection of such topological surface state has been considered as the fingerprint prove for crystals with nontrivial topological bulk band. On the contrary, it has been proposed that even with symmetry broken at the surface, a new surface band can emerge in nonsymmorphic topological semimetals. The symmetry reduction at the surface lifts the bulk band degeneracies and produces an unusual “floating” surface band with trivial topology. Here, we first report quantum …

Mechanical Properties, Translucency, And Low Temperature Degradation (Ltd) Of Yttria (3–6 Mol%) Stabilized Zirconia, R. Sharon Uwanyuze, Sulekha Ramesh, Mark K. King, Nathaniel Lawson, Manoj K. Mahapatra

Materials Science and Engineering Faculty Research & Creative Works

The mechanical properties (hardness and biaxial flexural strength), optical properties (translucency and gloss), and low temperature degradation (LTD) of 3–6 mol% yttria stabilized zirconia have been investigated. The specimens were prepared by conventional solid-state sintering at 1400 °C. The mechanical and optical properties were evaluated for sintered and polished specimens. X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used, respectively, for structural and microstructural investigation. LTD was determined by XRD analysis of the samples aged in a hydrothermal autoclave at 134 °C for 5–108 h. The mechanical and optical properties are found to be microstructure sensitive. The LTD, due …

Metallurgical And Thermal Processing Investigation Of Additively Manufactured Superalloys Jbk-75 And Nasa-Hr-1, Allyse Birken, Derek Noel

Materials Engineering

Aerojet Rocketdyne is investigating the use of directed energy deposition (DED), an additive manufacturing process, to reduce cost and lead time for manufacturing complex rocket engine components for their RS-25 engines. JBK-75 and NASA-HR-1, two Fe-Ni-base, age-hardenable (γ′) superalloys, are used for nozzle structural jackets and hot gas manifolds. Currently, these parts are produced using traditional forging or casting methods followed by intensive machining operations. Additionally, these alloys were designed for use in the wrought condition and require a different set of post-processing heat treatments when produced using DED due to their dendritic, segregated microstructure in the as-built condition. Homogenization …

Void And Density Analysis Of Cyanate Ester Composites, Cameron B. Atwood

Materials Engineering

In large scale composite manufacturing, voids and their frequency within prepreg materials play an important role in predicting the mechanical properties of a final composite laminate. The industry standard process for determining voids in composite materials is through resin digestion and resin ignition via ASTM D3171. One limitation to this standard is its ability to frequently produce negative void volume values in quality control testing, due to the calculation sensitivity of input resin and fiber densities. For this reason, Toray Advanced Composites wanted to investigate the process steps of ASTM D3171 to determine if discrepancies in resin density data may …

Dental Cement Thickening Agents For Mudslide Prevention, Kristina Emiliya Babayev, Emily Elizabeth Johnson, Diana Evet Reihaneh

Materials Engineering

The purpose of this project is to develop a non-toxic mud thickening agent for the application of decreasing mudslide intensity where performance is measured by flow rate, viscosity, and toxicity tests. We hypothesized that dental cements could be a potential candidate due to their adhesive, hydrophilic, and biocompatible properties. Zinc phosphate, glass ionomer, and polycarboxylate cement were among the dental cements tested. These tests were performed at low and high concentrations of 25 grams and 125 grams, respectively, mixed into soil to produce 3500 gram samples. The dental cements produced noticeable thickening effects in the mud, as the average viscosity …

First-Principles Density Functional Theory Studies On Perovskite Materials, Aneer Lamichhane

Dissertations

Perovskites are a family of materials with a diverse combination of different elements. As a consequence, they exhibit numerous functionalities such as pyroelectric, piezoelectric, ferroelectric, and ferromagnetic with applications in photovoltaic cells, LEDs, superconductivity, colossal magneto-resistance, and topological insulators. After 2009, perovskites have gained notoriety as suitable materials for solar cells and alternative candidates to silicon-based conventional solar cells. Generally, oxide perovskites exhibit good dielectric properties, halide perovskites display good photonic qualities, and chalcogenide perovskites are used in applications in solid-state lighting, sensing, and energy harvesting. In this dissertation, various types of perovskites ranging from oxide to halide are investigated …

Fluorine-Based Inorganic Oxidizers For Use In Metal-Based Reactive Materials, Siva Kumar Valluri

Dissertations

This work explores inorganic fluorides as oxidizers for fuel-rich reactive materials. A preliminary assessment of metal fluorides accounting for their enthalpy of formation points to bismuth (III) fluoride, BiF3 and cobalt (II) fluoride, CoF2 as oxidizers of interest. Initially, composite powders of aluminum with chosen fluorides at 50-50 wt. % are prepared by arrested reactive milling. Despite an increase in reactivity and lowtemperature ignition, the prepared composite powders are insensitive to initiation by electro-static discharge (ESD), making them attractive alternative to analogous thermites having very high ESD sensitivity. In air, the composite powder particles burn faster than reference aluminum particles …

Controlled Reduction Of Graphene Oxide And Graphene Oxide-Carbon Nanotube Hybrids And Their Applications, Samar Azizighannad

Dissertations

Graphene and graphene derivatives are widely used in diverse research and industrial applications. Graphene production on a large scale is carried out by exfoliating graphite oxide and producing graphene oxide (GO), which comprises of graphene sheets with different oxygen-containing functional groups such as hydroxyl, carboxyl, and carbonyl. GO is reduced to reduced graphene oxide (rGO), which has properties that are closer to graphene. Properties of GO and rGO depend upon the oxygen content, and the effect of reducing oxygen content on the aqueous behavior of rGOs is not well understood.

In an effort to understand how properties of rGO change …

Copper Slag As A Potential Waste Filler For Polyethylene-Based Composites Manufacturing, Aleksander Hejna, Paulina Kosmela, Mateusz Barczewski, Olga Mysiukiewicz, Adam Piasecki

Tanzania Journal of Science

The present study aimed to analyze the application of waste material from copper production– copper slag (ŻŻL) as filler for composites based on the high-density polyethylene (HDPE). Copper slag filler was introduced in the amounts of 1–20 wt%, and its influence on the appearance (color analysis), chemical structure (Fourier-transform infrared (FTIR) spectroscopy), microstructure (optical microscopy), as well as static (tensile tests) and dynamic (dynamical mechanical analysis (DMA)) mechanical properties of composites were investigated. Proper dispersion of filler implicated that the incorporation of up to 5 wt% of filler caused only slight, 5% drop of tensile strength, with the simultaneous 16% …

Upgrading Biogas Using Eburru Zeolitic Rocks And Other Adsorbent Materials To Remove Carbon Dioxide And Hydrogen Sulphide, James K Mbugua, Joseph M Mwaniki, Damaris M Nduta, Francis B Mwaura

Tanzania Journal of Science

The trace amounts of carbon dioxide and hydrogen sulfide in raw biogas lower its calorific value,cause corrosion and make it hard to compress biogas into the cylinder. Raw biogas was obtainedfrom anaerobic digestion of cow dung and market wastes. The gas was stored in tubes or urine bagbefore upgrading. Natural zeolite rocks, maize cobs, steel wire, desulphurizer, and worn-out tyreswere used as the upgrade materials. The composition of biogas was recorded before and afterupgrading using a GP180 portable biogas analyzer from Henan, China. The measured level of rawbiogas was 0.0227% H2S, >20% CO2 and 52-56% CH4. The most efficient upgrade …

Assessment Of Natural Radioactivity And Radiation Hazards Of Building Materials In Kinondoni District, Dar Es Salaam, Tanzania, Huruma P Mammba, Vitus A Balobegwa, Alex P Muhulo, Peter A Pantaleo, Remigius A Kawala

Tanzania Journal of Science

Natural radionuclides from building materials are one of the potential sources of external as well as internal radiation exposure to the human body. Currently, this exposure has been increasing since people spend more than  of their time indoors (ICRP 1991). Commonly used building materials from Kinondoni District were investigated using γ-spectrometry; their activity concentrations of 226Ra, 232Th and 40K in Bq/kg were measured. The results showed that average values of activity concentrations of 226Ra, 232Th and 40K were 15.62, 21.51 and 237.99 Bq/kg, respectively. All the activity concentrations in the studied samples were lower than the world average values of …

Influence Of Carbonitriding Conditions On Phase Composition And Residual Stresses For 20mncr5 Low Alloy Steel, Richard J Katemi, Jeremy Epp

Tanzania Journal of Science

This paper reports an investigation of the influence of carbonitriding conditions for 20MnCr5 low alloy steel. Three gaseous carbonitriding conditions were investigated based on different carbon and nitrogen potentials to attain varying levels of carbon between 0.62 and 0.93% mass, whereas for nitrogen between 0.19 and 0.26% mass at the surface. Analysis of retained austenite and residual stress distributions was conducted using X-ray diffraction technique. The effective case depth varied between 900 and 1200 µm. The case microstructures were characterized by varying proportions of retained austenite and martensite, while the core contained essentially bainitic microstructures. The maximum amount of retained …

Use Of Biomimicry Design Approach In Constructing Sustainable Resilient Structures (Case Study: Port Of Beirut), Farouk Bader, Marwan Halabi, Hiba Mohsen, Maged Youssef

BAU Journal - Creative Sustainable Development

Resiliency is not the same as sustainability, nor its substitute, but definitely the two concepts complement each other’s. Sustainability is the avoidance of depletion of natural resources to maintain ecological balance whereas resiliency is to recover, adapt and keep going in the face of setbacks. While designing with green approach is important but what will happen to leed points if the building becomes uninhabitable due to disasters, that’s where resiliency comes into play. The 2019 statistics showed that natural disasters accounted for 133 billion dollars losses and manmade ones accounted for other 7 billion in addition to 11,755 people worldwide …

First-Principles Studies Of Substituent Effects On Squaraine Dyes, German Barcenas, Austin Biaggne, Olga A. Mass, Christopher K. Wilson, Ryan D. Pensack, Jeunghoon Lee, William B. Knowlton, Bernard Yurke, Lan Li

Materials Science and Engineering Faculty Publications and Presentations

Dye molecules that absorb light in the visible region are key components in many applications, including organic photovoltaics, biological fluorescent labeling, super-resolution microscopy, and energy transport. One family of dyes, known as squaraines, has received considerable attention recently due to their favorable electronic and photophysical properties. In addition, these dyes have a strong propensity for aggregation, which results in emergent materials properties, such as exciton delocalization. This will be of benefit in charge separation and energy transport along with fundamental studies in quantum information. Given the high structural tunability of squaraine dyes, it is possible that exciton delocalization could be …

Cyclic Regeneration Of Nanostructured Composites For Catalytic Applications, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

A cermet catalyst material, defining a matrix having interconnected open pores, the matrix selected from the group consisting of YSZ and CGO and defining a substrate, a ceramic coating having a general formula AyBnOx at least partially coating the pores, and a plurality of metal particles A at least partially embedded in the ceramic coating. A is selected from the group consisting of Co, Cu, Ce, Ni, Ti, and combinations thereof and B is selected from the group consisting of Mo, W, Ce, and combinations thereof. When the coating is in a first oxidizing atmosphere and at a temperature between …

Effects Of Air Pollution, Temperature And Moisture Content On Copper And Silver Corrosions And The Reliability Of Data Center Equipment, Rui Zhang

Dissertations - ALL

The effects of moisture content, temperature, and pollutant mixture on atmospheric corrosion of copper and silver were investigated by exposing test specimens to different environmental conditions, followed by surface characterization using the coulometric reduction, Scanning Electron Microscopy, and Energy Dispersive Spectrometry (SEM/EDS). Printed circuit board test cards (PCBs) with bare copper were also used to investigate the effects of voltage bias on the PCBs on the corrosion rate. The test specimens were exposed to mixed flowing gases (MFG) environment with eight different combinations of the following five pollutants at the fixed concentration levels: 60 ppb O3, 80 ppb NO2, 40 …

Mash 2016 Test Level 3 And Test Level 4 Evaluation Of Roadside Safety Barrier With Pedestrian Features, Miguel Angel Hinojosa Palacios

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The Minnesota Department of Transportation (MnDOT) desires to use a vehicle, bicycle, and pedestrian combination bridge railing system along pedestrian and bicycle bridge paths. The system was evaluated per MASH 2016.

In full-scale crash test no. MNPD-3, the system was evaluated according to MASH test designation no. 3-11. The 2014 Dodge Ram 1500 crew cab pickup truck impacted the system 71¼ in. upstream from the centerline of post no. 4 with a speed of 63.4 mph at an angle of 25.3 degrees. The combination railing system was found to meet the AASHTO MASH 2016 TL-3 impact safety criteria.

MnDOT uses …

Effects Of Air Pollution, Temperature And Moisture Content On Copper And Silver Corrosions And The Reliability Of Data Center Equipment, Rui Zhang

Dissertations - ALL

The effects of moisture content, temperature, and pollutant mixture on atmospheric corrosion of copper and silver were investigated by exposing test specimens to different environmental conditions, followed by surface characterization using the coulometric reduction, Scanning Electron Microscopy, and Energy Dispersive Spectrometry (SEM/EDS). Printed circuit board test cards (PCBs) with bare copper were also used to investigate the effects of voltage bias on the PCBs on the corrosion rate. The test specimens were exposed to mixed flowing gases (MFG) environment with eight different combinations of the following five pollutants at the fixed concentration levels: 60 ppb O3, 80 ppb NO2, 40 …