Engineering Commons^™

Evaluation Of A Threshold-Based Model Of The Elevated-Temperature Fatique Of Impact-Damaged Γ-Tial, Trevor S. Harding, J. Wayne Jones

Materials Engineering

Step-loading fatigue tests have been conducted on two γ-TiAl alloys with differing microstructures following quasi-static indentations intended to simulate assembly-related impact damage to low-pressure turbine blades. Fatigue tests were conducted at 600 °C using computer-controlled servohydraulic loading at a frequency of 20 Hz. Reasonably good agreement was achieved between the fatigue data and calculated fatigue strength based on the fatigue threshold and measured impact severity. In certain cases, the fatigue threshold model fails to completely describe the data. These discrepancies may be related to residual stresses, variations in crack-shape morphology, and small-crack effects. Residual stresses could not be directly measured, …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Aaa Task-4 Quarterly (September 1 – November 30, 2001) Report, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including HT- 9, EP 823 and 422. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these alloys will be evaluated in environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. The extent and morphology of cracking of these alloys will further be evaluated …

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823: Task 10, First Quarter Report, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The objective of this task is to evaluate the elevated temperature tensile properties of Alloy EP-823, a leading target material for accelerator-driven waste transmutation applications. The test material will be thermally treated prior to evaluation of its tensile properties at temperatures relevant to the transmutation applications. The deformation characteristics of tensile specimens, upon completion of testing, will be evaluated by surface analytical techniques including scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The overall results are expected to provide a mechanistic understanding of high-temperature deformation behavior of Alloy EP-823 as a function of heat treatment.

Highlights of Accomplishment

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Modeling, Fabrication, And Optimization Of Niobium Cavities – Phase I: Quarterly Progress Report August 20, 2001 - November 20, 2001, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch. A nonuniform surface etch will leave some unclean areas with contaminants and micron size particles. These significantly affect mutipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical …

Analysis Of Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

We examined stainless samples that were exposed to LBE in experiments conducted by the Russians, under contract to Los Alamos. We examined both corroded and uncorroded samples using the Scanning Electron Microscope (SEM), the Energy Dispersive X-Ray (EDAX) Spectroscopy, and the X-ray Photoelectron Spectrometer (XPS). We found that the surface of the corroded sample is covered by oxygen-containing compounds, presumably mostly iron oxide. In samples exposed for shorter times or lower temperatures, we found that some areas were covered by an oxide layer, and some areas was uncovered. We found that the level of Cr in the uncovered area is …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report August 16,2001- November 15, 2001, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the AAA proposed application.

Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with very limited density. The transport of oxygen and corrosion products, their interaction and variation of corrosion/precipitation along the flow are not well understood.

The first subtask of this project involves using a …

Size-Induced Lattice Relaxation In Ceo₂ Nanoparticles, X.-D. Zhou, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

Size-induced lattice relaxation was observed for nanoscale CeO₂ single crystals with an average size from 4 to 60 nm. Results showed the finest crystallites exhibited no strain-induced line broadening, while high temperature annealing resulted in larger grain sizes and significant strains. The observed shift in the x-ray diffraction lattice parameters was assumed to be due to the formation of defects on the lattice, specifically oxygen vacancies. Modeling revealed that the oxygen vacancy concentration ([V^••_O]) was found to be ≈4 x 10²⁰/cm³ for the 4 nm crystallites, and decreased two orders of magnitude for …

Capillary Flow In Interior Corners: The Infinite Column, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

Capillary flow of a sinusoidally perturbed liquid column in an interior corner of infinite extent is solved using lubrication theory. Due primarily to the length scales selected to nondimensionalize the momentum equation, an analytic time scale governing the settling of the perturbation is determined. The time scale, which is shown to be independent of a steady base state flow, proves useful in rapidly predicting transients for surface settling in certain liquid-bearing tanks of spacecraft employing interior corners for fluids management purposes. The asymptotic analysis is extended to address flows along interior corners whose faces are slightly nonplanar. The generalized formulation …

Silica-Based Membrane Sorbent For Heavy Metal Sequestration, Dibakar Bhattacharyya, Stephen M. Ritchie, Leonidas G. Bachas, Jamie A. Hestekin, Subhas K. Sikdar

Chemical and Materials Engineering Faculty Patents

An apparatus providing for metal ion/nitrate entrapment comprises a chemically activated, microfiltration, composite polymer and silica-based membrane including a polyamino acid attached thereto through reaction of a terminal amine group of the polyamino acid with the membrane. A method for preparing such a chemically activated or polyamino acid functionalized membrane includes the steps of permeating the silica-based membrane with a solution of silane and a solvent so as to react methoxy groups of the silane with silanol groups of the membrane to incorporate epoxide groups and attaching a polyamino acid to the membrane by reacting a terminal amine group of …

Ultrasonic Characterization Of Poling In Lead Zirconate Titanate Ceramics, James R. Friend, Eric Jamieson, Marvin Pennell, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

A method for measuring the spatial variation of the macroscopic poling state of a piezoelectric material using an ultrasonic transducer is described. The relatively simple method clearly indicates the distribution of poling within the material, demonstrated by the testing of a collection of partially poled lead zirconate titanate samples.

Highly Plasma Etch-Resistant Photoresist Composition Containing A Photosensitive Polymeric Titania Precursor, Tony D. Flaim, Douglas J. Guerrero, Michelle R. Fowler, William Joseph James, Vladimir Petrovsky, Harlan U. Anderson

Chemistry Faculty Research & Creative Works

A composition is derived from an addition polymerizable organotitanium polymer which upon exposure to an oxygen plasma or baking in air, is converted to titanium dioxide (titania) or is converted to a mixed, titanium-containing metal oxide. The metal oxide formed in situ imparts etch- resistant action to a patterned photoresist layer. The composition may also be directly deposited and patterned into permanent metal oxide device features by a photolithographic process.

The Current State Of Research On Academic Dishonesty Among Engineering Students, Trevor S. Harding, Donald D. Carpenter, Susan M. Montgomery, Nicholas H. Steneck

Materials Engineering

Academic dishonesty, or cheating, has become a serious problem at colleges and universities. This is particularly true of engineering students who, are among the most likely to cheat in college. The present paper reviews the literature as a basis of broadly understanding academic dishonesty. This discussion focuses on three primary issues: (1) perceptions of and attitudes towards cheating, (2) reasons for student cheating, and (3) methods of promoting academic integrity. A current research project being developed by the authors is also discussed. The premise of this research is that students are constantly making ethical judgements between the pressure to cheat …

Process For Making A Lubricating Composition, Stephen J. Miller, Gerald P. Huffman, Naresh Shah

Chemical and Materials Engineering Faculty Patents

The invention includes a process of making a lubricating oil composition including: a process for making a high VI lubricating oil composition including the steps of (1) contacting a waste plastics feed including mainly polyethylene in a pyrolysis zone at pyrolysis conditions, whereby at least a portion of the waste plastics feed is cracked, thereby forming a pyrolysis zone effluent including 1-olefins and n-paraffins; (2) passing the pyrolysis zone effluent, including a heavy fraction and a middle fraction, the pyrolysis effluent middle fraction including 1-olefins, to a separations zone; where the pyrolysis effluent heavy fraction portion is separated from the …

Hfco2 Laves Phase Intermetallics - Part Ii: Elastic And Mechanical Properties As A Function Of Composition, Katherine C. Chen, Fuming Chu, Paul G. Kotula, Dan Thoma

Materials Engineering

In efforts to establish and understand structure–property relationships in Laves phase intermetallics, elastic and mechanical properties are studied as a function of composition in the C15 HfCo₂ system. Elastic constants and Debye temperatures are determined by resonant ultrasound spectroscopy (RUS) at room temperature. A maximum near the stoichiometric Laves composition is revealed with the Young's modulus, bulk modulus, and Poisson's ratio. In addition, a slight drop in shear modulus is found with Co-rich compositions, and the Debye temperature increases with Co-content. Room temperature Vickers indentation is performed to assess the microhardness and fracture toughness of the HfCo₂ alloys. …

Hfco2 Laves Phas Intermetallics - Part I: Solubility Limits And Defect Mechanisms, Katherine C. Chen, Eric J. Peterson, Dan J. Thoma

Materials Engineering

Solubility limits and constitutional defects in Laves phase intermetallics are investigated with the C15 HfCo₂ system. Several binary alloy compositions based on HfCo₂ are characterized by optical and scanning electron microscopy (SEM), electron microprobe analysis (EPMA), X-ray diffraction (XRD), and density measurements. Rietveld refinements of XRD scans are used to determine lattice constants, anisotropic strain parameters, and atomic occupancies. Compositional trends are compared against predicted or calculated trends due to an anti-site substitution or vacancy defect mechanism. Geometric models and atomic size factors are used to establish solubility limits and to give insight into defect mechanisms. Results from …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Aaa Task-4 Quarterly (June 1 – August 31, 2001) Report, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The subject task entitled “Hydrogen-Induced Embrittlement of Candidate Target Materials for Applications in Spallation-Neutron-Target Systems” had commenced during the quarter ending on August 31, 2001. A research account has been established, contracts for both faculty and students have been prepared, and efforts are well underway to embark on the related research activities, as proposed.

As the title of this project implies, the primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate materials for applications in spallationneutron- target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). …

Disclination Loop Behavior Near The Nematic-Isotropic Transition, Nikolai V. Priezjev, Robert A. Pelcovits

Mechanical and Materials Engineering Faculty Publications

We investigate the behavior of disclination loops in the vicinity of the first-order nematic-isotropic transition in the Lebwohl-Lasher and related models. We find that two independent measures of the transition temperature, the free energy, and the distribution of disclination line segments, give essentially identical values. We also calculate the distribution function D(p) of disclination loops of perimeter p and fit it to a quasiexponential form. Below the transition, D(p) falls off exponentially, while in the neighborhood of the transition, it decays with a power-law exponent approximately equal to 2.5, consistent with a “blowout” of loops at the transition. In a …

Modeling, Fabrication, And Optimization Of Niobium Cavities – Phase I: Quarterly Progress Report May 15, 2001 - August 15, 2001, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch compromising the optimal geometrical design. Past multipacting studies have not examined the impact of wall perturbations.

It is the purpose of this study to examine the chemical etching process in the design of niobium cavities so to maximize the surface quality of …

Analysis Of Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

The goal is to achieve a basic understanding of the corrosion of stainless steel by Lead Bismuth Eutectic (LBE), which has been proposed for use in the transmuter as both a coolant and as a sputtering target.

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications, Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the elevated temperature tensile properties of Alloy EP- 823, a leading target material for accelerator-driven waste transmutation applications. This alloy has been proven to be an excellent structural material to contain the lead-bismuth-eutectic (LBE) nuclear coolant needed for fast spectrum operations. However, very little data exist in the open literature on the tensile properties of this alloy. The selection of Alloy EP-823 as the test material in the proposed task is based on the recommendation of our collaborator at the Los Alamos National Laboratory (LANL). The test material will be thermally treated …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes of two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. …

Ni-Induced Local Distortions In La₁.₈₅Sr₀.₁₅Cu1-YNiYO₄ And Their Relevance To Tc Suppression, Daniel Haskel, Edward A. Stern, Victor Polinger, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

We present results from angular-resolved x-ray-absorption fine-structure (XAFS) measurements at the Ni, La, and Sr K edges of oriented powders of La1.85Sr0.15Cu1-yNiyO4, with y=0.01, 0.03, 0.06. A special magnetic alignment procedure allowed us to measure pure ĉ- and ab-oriented XAFS at the Ni K edge in identical fluorescence geometries. Both the x-ray-absorption near-edge structure and the XAFS unequivocally show that the NiO6 octahedra are contracted along the c axis by ≈0.32Å relative to CuO6 octahedra while the in-plane distances of NiO6 and CuO6 octahedra are the same within 0.01Å. The NiO6 octahedral contraction drives the average ĉ axis contraction measured …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems, Brendan O'Toole, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the effect of hydrogen on cracking of candidate target materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The test materials will undergo appropriate thermal treatments prior to being hydrogen-charged by potentiostatic cathodic polarization technique in a simulated aqueous environment at different temperatures of interest. The specimens, upon completion of testing, will be metallographically examined. Further, the scanning electron microscopy (SEM) will be used to determine the extent and nature of cracking in the specimens tested. The thrust of the proposed …

The Foundation Series On Corrosion: Integrating Science, Math, Engineering & Technology In A Lab Setting, Linda Vanasupa, Heather Smith, Blair London, Katherine C. Chen, David Niebuhr, Lanny Griffin, Jeff Jones

Materials Engineering

We have developed a laboratory module focusing on the subject of corrosion. The module itself is designed to be completed in one three-hour session. It consists of three parts: I. The Impact of Corrosion Media, II. The Impact of Corroding Materials, III. The Impact of Anode/Cathode Sizes. Our objectives in developing this module were to address the need for clear bridges between math, science and technology in the engineering curriculum and to provide a means of faculty development primarily at community colleges. As a result, it was designed to allow the engineering student to experience the synergy of science, math …

Asee Student Chapters: From Student Members To Faculty, Jennifer Kadlowec, Kurt Degoede, Trevor S. Harding, Christian Lorenz

Materials Engineering

The University of Michigan Student Chapter of the American Society for Engineering Education has grown from a small core group of founding members, who organized panel discussions for the graduate student community, into a flourishing student organization, which continues to grow in membership and events. The purpose of this paper is to promote graduate student chapters of the ASEE and demonstrate the positive impact that student member participation has had, particularly for those who have recently entered academia. Many events and activities of the University of Michigan Student Chapter of the American Society for Engineering Education (UM-ASEE Student Chapter) will …

Useful Approaches To Preventing Academic Dishonesty In The Classroom, Trevor S. Harding

Materials Engineering

Over the past three decades, academic dishonesty (a.k.a. cheating) has become an increasingly common occurrence among college-aged students, and engineering students are known to be among the most frequent culprits. At most universities, cheating is dealt with after the fact. Few institutions go beyond drafting an academic integrity policy to prevent cheating before it happens. The same situation exists in the classroom. The majority of college professors report doing little or nothing to reduce the frequency of cheating in their classes, usually because of a lack of awareness of its occurrence. And when cheating is observed, faculty overwhelmingly choose to …

On The Frequency And Causes Of Academic Dishonesty Among Engineering Students, Trevor S. Harding

Materials Engineering

According to studies of self-reported academic dishonesty conducted over time, cheating among college students has been on the increase since at least the 1940’s. This is especially true for engineering students who are now among the most likely to cheat compared to other disciplines. This paper will present a synopsis of the literature on academic dishonesty. In addition, the results of a pilot study on cheating among engineering students conducted at a small mid-western private engineering school are described. Engineering students in an introductory engineering materials course were asked to complete a survey on their perceptions of cheating; therefore, all …

Plasma Deposition Of Spin Chucks To Reduce Contamination Of Silicon Wafers, Richard N. Savage, Emir Gurer, Ed C. Lee

Materials Engineering

An apparatus for delivering a fluidic media to a wafer includes a housing defining a process chamber. A fluidic media delivery member is coupled to the process chamber. A rotatable chuck is positioned in the process chamber. The rotatable chuck has a wafer support surface coated with a coating material. A vacuum supply line is coupled to the rotatable chuck.

Cluster Monte Carlo Simulations Of The Nematic--Isotropic Transition, Nikolai V. Priezjev, Robert A. Pelcovits

Mechanical and Materials Engineering Faculty Publications

We report the results of simulations of the three-dimensional Lebwohl-Lasher model of the nematic-isotropic transition using a single cluster Monte Carlo algorithm. The algorithm, first introduced by Kunz and Zumbach to study two-dimensional nematics, is a modification of the Wolff algorithm for spin systems, and greatly reduces critical slowing down. We calculate the free energy in the neighborhood of the transition for systems up to linear size 70. We find a double well structure with a barrier that grows with increasing system size. We thus obtain an upper estimate of the value of the transition temperature in the thermodynamic limit.

Studies On The Formation Of Dna-Cationic Lipid Composite Films And Dna Hybridization In The Composites, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Krishna N. Ganesh

Faculty Works

The formation of composite films of double-stranded DNA and cationic lipid molecules (octadecylamine, ODA) and the hybridization of complementary single-stranded DNA molecules in such composite films are demonstrated. The immobilization of DNA is accomplished by simple immersion of a thermally evaporated ODA film in the DNA solution at close to physiological pH. The entrapment of the DNA molecules in the cationic lipid film is dominated by attractive electrostatic interaction between the negatively charged phosphate backbone of the DNA molecules and the protonated amine molecules in the thermally evaporated film and has been quantified using quartz crystal microgravimetry (QCM). Fluorescence studies …