Materials Science and Engineering Commons^™

Additive-Assisted Cerium-Based Electrolytic Coating Process For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Eric L. Morris, Scott Hayes, Paul Yu, Alex Williams, Xuan Lin

Chemistry Faculty Research & Creative Works

The corrosion resistance of an aluminum or aluminum alloy component is enhanced by immersing an aluminum alloy to act as a cathode and an oxygen-evolving anode in an electrolyte comprising water, cerium ions, and an additive selected from among animal gelatin, derivatives of animal gelatin, and amino acids, then passing an electrical current through the electrolyte to deposit a cerium-based coating onto the aluminum-based component.

Environmental Effects On Corrosion Properties Of Alloy 22, K. S. Raja, L. G. Mcmillion, Shantanu A. Namjoshi, Paige Russel, Raymond E. Keeler, Amy J. Smiecinski

Publications (YM)

During the regulatory life of the Yucca Mountain High Level Nuclear Waste (HLNW) repository the primary engineered barrier that is to prevent release of radioactive material into the environment is proposed to be a Corrosion-Resistant Material (CRM) outer shell covering the Waste Package (WP) container. The current selection for the CRM is Alloy 22 (UNS N06022), a Ni-Cr-Mo-W-Fe alloy. Alloy 22 forms a defective chromic oxide passive film which results in excellent corrosion resistance; the presence of molybdenum in Alloy 22 offers corrosion resistance in reducing environments as well as oxidizing environments.

Disorder-Induced Depression Of The Curie Temperature In Mechanically Milled Gdal2, Marco Morales Torres, D. S. Williams, Paul M. Shand, C. Stark, Thomas M. Pekarek, Lanping Yue, Valeri G. Petkov, Diandra Leslie-Pelecky

Materials Research Science and Engineering Center: Faculty Publications

The effect of disorder on the ferromagnetic transition is investigated in mechanically milled GdAl₂. GdAl₂is a ferromagnet when crystalline and a spin glass when amorphous. Mechanical milling progressively disorders the alloy, allowing observation of the change from ferromagnetic to a disordered magnetic state. X-ray diffraction and pair-distribution-function analysis are used to determine the grain size, lattice parameter, and mean-squared atomic displacements. The magnetization as a function of temperature is described by a Gaussian distribution of Curie temperatures. The mean Curie temperature decreases with decreasing lattice parameter, where lattice parameter serves as a measure of defect concentration. …

Single Chamber Electrolyte Supported Sofc Module, Toshio Suzuki, Piotr Jasinski, Harlan U. Anderson, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

An electrolyte supported single chamber solid oxide fuel cell (SOFC) module consisting of two cells has been proposed. The module consists of one Sm-doped CeO₂ (SDC) electrolyte substrate (0.5 mm thick with the size of 5 3 10 mm), two Ni-SDC anodes on one side, and two SDC-(La,Sr)(Co,Fe)O₃ cathodes on the other side. Two modules with different electrode areas were prepared and tested using an air-propane mixture. The electrode area had a strong influence on the performance of the module. It was shown that the two-cell module generated 1.5 V open-circuit voltage and about 17 mW maximum power …

Phase Stability And Segregation In Alloy 22 Base Metal And Weldments, Jeffrey Lacombe, Shantanu A. Namjoshi, Paige Russel, Raymond E. Keeler, Amy J. Smiecinski

Publications (YM)

The current design of the waste disposal containers relies heavily on encasement in a multi-layered container, featuring a corrosion barrier of Alloy 22, a Ni-Cr-Mo-W based alloy with excellent corrosion resistance over a wide range of conditions. The fundamental concern from the perspective of the Yucca Mountain Project, however, is the inherent uncertainty in the (very) long-term stability of the base metal and welds. Should the properties of the selected materials change over the long service life of the waste packages, it is conceivable that the desired performance characteristics (such as corrosion reistance) will become compromised, leading to premature failure …

The Role Of Moral Philosophy In Promoting Academic Integrity Among Engineering Students, Brian K. Etter, Trevor S. Harding, Cynthia J. Finelli, Donald D. Carpenter

Materials Engineering

Academic dishonesty is nothing new, yet it is particularly disturbing to find among engineering students, whose professional lives need to be guided by the highest ethical standards. Moral philosophy may illuminate some of the conditions for recovering a sense of the ethical for engineering students. Classical moral philosophers held that people belong to communities in ways that inform their sense of obligation. Recognition of these communities would make concrete the engineer's responsibility for the health, safety and welfare of the public. A further difficulty is that the primary community that students know is simply that of their peers in school …

Work In Progress – Classical Ballet Structure And Practice Applied To Engineering Class Sessions, Blair London, Lisa Deyo

Materials Engineering

Classical ballet classes have a universal structure that fosters active in-class learning. This structure creates a safe environment for students to try, fail, be corrected, and succeed. Engineering classes lack a common structure; most learning in engineering occurs outside of class. Engineering classes could move toward adopting a similar structure to ballet to improve in-class learning and mirror engineering culture and practice. The paper describes aspects of ballet class structure and practices that work and how these can apply to engineering classes. A new engineering class session structure is presented following the ballet model where engineering students are motivated to …

Rare Earth-Aluminum Oxide Glasses For Optical Applications, Richard Weber, Jean A. Tangeman, Paul C. Nordine, Richard N. Scheunemann, Kirsten J. Hiera, Chandra S. Ray

Materials Science and Engineering Faculty Research & Creative Works

Glasses based on rare earth oxides and aluminum oxide with 0-20 mol% SiO₂ provide a combination of optical properties, mechanical and chemical stability, and process characteristics not available in other oxide materials. Properties of the glasses include: refractive index 1.7-1.8, low dispersion (Abbe number ∼40), high solubility of optically active dopants, homogeneous chemical composition, long fluorescence lifetimes at dopant concentrations up to 5 mol%, broad fluorescence bandwidth, and infra-red transmission to ≈5000nm. the glasses are hard, strong and resist chemical attack and they can be cast in sections 5-10mm thick. This paper briefly describes glass processing and presents bulk …

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications: Final Progress Report (September 2003 – August 2004), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this task is to evaluate the tensile properties of three martensitic alloys namely, Alloys EP-823, HT-9 and 422 at temperatures relevant to the transmutation processes. Testing has been performed to evaluate the tensile properties of all three alloys at temperatures ranging from ambient to 600^°C. The test materials were thermally-treated (quenched and tempered) prior to the evaluation of their tensile properties. The deformation characteristics of these tensile specimens, upon completion of testing, were evaluated by scanning electron microscopy (SEM). Efforts were also made to identify and characterize defects such as dislocations using transmission electron microscopy …

Modeling, Fabrication, And Optimization Of Niobium Cavities Phase Iii: Quarterly Report, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

This quarterly report provides an update to the last phase of the Modeling, Fabrication, and Optimization of Niobium Cavities. Designing the experimental setup of secondary electron emission was well underway in early summer of 2003 when funding was made available for this portion the study. By March 2004, many of the components of the experimental study reached UNLV with some assembly accomplished. The first secondary electron emission (SEE) measurement was made from the surface of a Faraday cup in September 2004. At a particular beam energy, the current measured with the Faraday cup and electrometer changed sign over a range …

Use Of Positron Annihilation Spectroscopy For Stress-Strain Measurements: Quarterly Progress Report (June 01 – August 31, 2004), Ajit K. Roy

Transmutation Sciences Materials (TRP)

Highlights of Test Results:

• Residual stress measurements by the RC method on cold-worked specimens showed tensile residual stresses in austenitic stainless steel. However, compressive residual stresses were observed in martensitic stainless steel. This difference may be attributed to the difference in metallurgical phases and microstructures resulting from different thermal treatments imparted to them.

• Residual stress measurements by both ND and RC techniques on welded specimens showed similar patterns. Welded specimens consisting of similar material showed tensile residual stresses in the vicinity of the fusion line (FL). However, welded specimens consisting of dissimilar materials (austenitic and martensitic stainless steel …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 1, Dhanesh Chandra, Jaak J.K. Daemen, Raul Rebak

Publications (YM)

The principal purpose of the cooperative agreement is to develop and continue providing the public and the Office of Repository Development (ORD) of the U.S. Department of Energy’s (DOE) Office of Civilian Radioactive Waste Management (OCRWM) with an independently derived, unbiased body of scientific and engineering data concerning the study of Yucca Mountain as a potential high-level radioactive waste repository. Under this agreement, the University and Community College System of Nevada (UCCSN) will perform scientific or engineering research, and maintain and foster collaborative working relationships between government and academic researchers. The following describes the objectives of Task 019 “Subsurface Corrosion …

Layer-By-Layer Self -Assembly For Enzyme And Dna Encapsulation And Delivery, Amish Patel

Doctoral Dissertations

Thin wall microcapsules were formed via Layer-by-Layer Self-Assembly of alternate adsorption of oppositely charged polyelectrolyte on microcores. After the core dissolution, empty polymeric shells with 20–25 nm thick walls were obtained. These microcapsules were loaded with Myoglobin, Hemoglobin and Glucose Oxidase by opening capsule pores at low pH and closing them at higher pH. The native structure of the enzyme was not affected due to different treatments. Biocompatible nanoshells were also prepared for encasing DNA. Using the same Layer-by-Layer Self-Assembly approach nanoparticle were constructed containing DNA as one of the layers. The nanoparticles of different architecture were used to deliver …

Computational Approaches To The Design And Analysis Of Stability Of Polypeptide Multilayer Thin Films, Bin Zheng

Doctoral Dissertations

The focus of this research is the development of computational approaches to understanding the physical basis of layer-by-layer assembly (LBL), a key methodology of nanomanufacturing. The results provided detailed information on structure which cannot be obtained directly by experiments.

The model systems chosen for study are polypeptide chains. Reasons for this are that polypeptides are no less polyelectrolytes than the more usual polyions, and one can control the primary structure of a polypeptide on a residue-by-residue basis using modern synthetic methods. Moreover, as peptides constitute one of the four major classes of biological macromolecules, research in this direction is expected …

High Temperature Heat Exchanger Project: Quarterly Progress Report July 1, 2004 Through September 30, 2004, Anthony Hechanova

Publications (NSTD)

UNLV hosted a meeting on NHI Materials and Heat Exchanger Design on Monday, May 17. Paul Pickard (Sandia National Lab) and Bill Corwin (Oak Ridge National Lab) facilitated the meeting. The purpose of the meeting was to summarize the hydrogen materials and heat exchanger requirements and priorities for UNLV staff and their collaborators to support the research proposal solicitation for the UNLV Research Foundation HTHX program. Attendance was heavier than anticipated and required a change of venue to accommodate the crowd of over 30.

Experimental And Theoretical Investigation Of Mixing In A Bottom Gas-Stirred Ladle, Jun Aoki, Brian G. Thomas, Jörg Peter, Kent D. Peaslee

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Defect Chemistry Of Mixed Ionic/Electronic P-Type Oxides, Harlan U. Anderson, Xiao-Dong Zhou, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The p-type perovskite structure oxides are finding use in a number of energy related applications. In particular they are being used as cathodes in fuel cells as well as dense oxygen separation membranes. The defect concentration and defect mobility determine the electrical properties. Since both of these are dependent upon the operating temperature and oxygen activity, it is important to understand how an oxide equilibrates with its environment. In this paper, a defect chemistry model for the oxidation-reduction behavior of p-type perovskites is reviewed with formulations in the (La,Sr)(Cr,Mn,Co,Fe)03 system being used as examples.

Mushy-Zone Rayleigh Number To Describe Macrosegregation And Channel Segregate Formation During Directional Solidification Of Metallic Alloys, Surendra N. Tewari, R. Tiwari, G. Magadi

Chemical & Biomedical Engineering Faculty Publications

A recently defined mushy-zone Rayleigh number (R-aM) that includes side-branching contributions to the mushy-zone permeability has been examined for its correlation with the longitudinal macrosegregation and channel segregate formation. The Rayleigh number shows (1) a strong correlation between the extent of longitudinal macrosegregation and increase in the mushy-zone convection and (2) a good ability to predict the formation of channel segregates during directional solidification.

Novel Yttrium-Stabilized Zirconia Polymeric Precursor For The Fabrication Of Thin Films, Roger M. Smith, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

An acetate-based polymeric precursor for producing yttrium-stabilized zirconia (YSZ) was developed. The precursor was prepared under ambient conditions and contains only yttrium and zirconium cations. Dense, crack-free films were fabricated with this precursor on alumina substrates at a rate of 60 nm per deposition, producing polycrystalline YSZ at temperatures as low as 600 °C. Grain growth in thin YSZ films followed Arrhenius equation with an activation energy approximately 0.45 eV. The residual strain in YSZ films decreased with increasing annealing temperature from 600 to 900 °C.

Pm Manufacturing Research Boosted By Continuous Sintering Furnace, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

University of Missouri-Rolla has recently acquired a Fluidtherm laboratory continuous sintering furnace. Custom designed and built for PM research, the furnace will allow current efforts in sintering development, pressure gas quenching of PM steels, optimisation of toughness and fatigue properties of PM parts, and production of metal matrix composites to be enhanced and extended.

Anode Supported Single Chamber Solid Oxide Fuel Cell In Ch 4 -Air Mixture, Toshio Suzuki, Piotr Jasinski, Vladimir Petrovsky, Harlan U. Anderson, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

In this study, yttrium-stabilized zirconia (YSZ) thin films 1-2 μm thick electrolyte have been prepared using NiO-YSZ anode as substrates. Fuel cell test was conducted with the single chamber configuration in methane-air gas mixture using (la,Sr)(Co,Fe) O3 (LSCF) as the cathode. Test results showed that the open-circuit voltage to be >0.8 V, with power density as high as 0.12 W cm−2. It was also shown that gas flow rate has a large influence on the performance of the fuel cell, which indicates the importance of the geometrical design for anode support fuel cell system.

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Fourth Quarterly Report 06/01/2004-08/31/2004, 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 TRP 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 only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Trp Final Report 09/01/2003-08/31/2004, 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 TRP 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 only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Surface Treatment Of Ferrous Alloys With Boron, Naruemon Suwattananont

Theses

Boronizing is a thermo-chemical surface hardening treatment in which boron atoms diffused into the metal substrate form the metallic boride layer, providing high hardness, corrosion resistance, and 3-10 times increasing service life. This type of surface treatment is widely used in many applications.

The purpose of this work was to investigate the structures and properties of boronized ferrous alloys. Three types of steels, AISI 1018 (plain low carbon steel), AISI 4340 (high strength alloy steel), and AISI 304 (austenitic stainless steel), were used for this study. The boronized AISI 1018 and AISI 4340 demonstrated the saw-tooth structure with average 75-76 …

The Electrochemical Behavior And Determination Of Gsh At The Powder Microelectrode, Jian Chen, Zhong-Yu He, Chuansin Cha, Huan Liu

Journal of Electrochemistry

In this paper, the electrochemical behavior of GSH at the surface of platinum(Pt) electrode, glass carbon(GC) electrode and acetylene black packed powder microelectrode (AB-PME) was studied. It was found that the electrochemical oxidations of GSH at both Pt and GC electrode were highly irreversible. No current peak or current plateau could be observed from the CV curves. The direct electro-oxidation of GSH at carbon surface was achieved by using the PME technique.In this case, the apparent reversibility of GSH oxidation was enhanced significatly .The overpotential of GSH oxidation was reduced to 0.5 V at the surface of AB-PME compared with …

Electrochemical Reduction Of Nitrobenzene On The Wc Electrode In Acidic Solution, Chun-An Ma, You-Qun Chu, Ying-Hong Zhu, Zhi-Hua Xu

Journal of Electrochemistry

The tungsten carbide (WC) electrode was constructed by using polyterafluoroethylene as binder. The electrochemical behavior of nitrobenzene on the WC electrode in acidic solution was investigated by cyclic voltammetry, linear scan method and chronoamperometry. Experimental results showed that WC electrode had good activity for the electrochemical reduction of nitrobenzene, and the electrode process was controlled by diffusion and electrochemical stepssimultaneously. The apparent active energy of the electrode process is 23.7kJ⋅mol^-1, while the active energy of the electrochemicalstep is 10.91kJ⋅mol^-1.

Solid State Synthesis And Electrocatalysis Of Pt/Moo3 For The Oxidation Of Methanol, Qing Wang, Yi-Ming Zhou, Yang Shao, Yi-Gang Ji, Juan Xu, Ya-Wen Tang, Tian-Hong Lu, Tao Shen

Journal of Electrochemistry

The electrocatalyst, Pt/MoO₃ synthesized by solid state reaction, was used for the oxidation of methanol in direct methanol fuel cells. The X-Ray diffraction and cyclic voltammetry were employed to investigate the performance of the material. It was shown that the typical diffraction peaks for Pt appeared in XRD. And a good electrocatalysis for methanol oxidation was observed. The peak potential of the methanol oxidation appeared at ca. 0.63V(vs.SCE) and the peak current density for the oxidation was 78.1 mA⋅cm^-2.

The Effect Of Ferrous Sulphate On The Electroless Depositionof Co-Fe-P Alloys, Sen-Lin Wang, Qing-Hua Li

Journal of Electrochemistry

Electroless deposition of Co-P alloy and Co-Fe-P alloy from an alkaline bath, containing sodium hypophosphite as a reducer, boric acid as a buffer agent and sodium citrate as a complexing agent, was investigated respectively. The effects of process parameters, such as pH of solution and metallic salt mole ratio of CoSO₄/FeSO₄, on the plating rate were examined. It was found that the presence of ferrous sulfate in the bath has an inhibitory effect on the alloy deposition. As a consequence, the plating rate of Co-Fe-P is lower than that of Co-P. The electrochemical polarization measurements have …

Study On An Intermediate Temperature Planar Solid Oxide Fuel Cell, Shao-Rong Wang, Wen-Xia Chen, Ting-Lian Wen, Jia-Di Cao, Zhi-Yi Lv, Da-Qian Wang

Journal of Electrochemistry

Tape cast method was applied to prepare green sheets of Ni/YSZ anode supported YSZ thin film. After isostatic pressure treatment and cosintering, the YSZ film on the Ni/YSZ anode was gas-tight dense, and 15~30 μm thick. The area of the composite film was over 100 cm². A Ce_0.8Sm_0.2O_1.9 (CSO) interlayer was sintered on to the YSZ electrolyte film to protect La_0.6Sr_0.4CoO₃ (LSCO) cathode from reaction with YSZ at high temperatures. The LSCO cathode layer was screen printed onto the CSO interlayer and sintered at 1200 ℃ for 3 …

Preparation Of Photo-Electrochemical Anticorrosion Tio2 Films By Anodization Method, Peng-Fei Wu, Mou-Cheng Li, Jia-Nian Shen, Mei-Qun Xiao, Dong Liu

Journal of Electrochemistry

Titanium oxide films have photo-electrochemical anticorrosion effect. We investigated the TiO₂ films prepared by anodization method to protect for 45# carbon steel in man-made seawater(3%NaCl). Various parameters, including voltages, electrolytes nature and concentration of electrolyte were examined. The polarization curves and of TiO₂ and coupling photo-current curve between TiO₂ film and 45#  carbon steel were measured.