Materials Science and Engineering Commons^™

Calcium Phosphate Film Coating On Titanium Substrate By Electrochemical Deposition, D P. Kashima, A Rakngarm

Journal of Metals, Materials and Minerals

Calcium phosphate film on titanium substrate was achieved by electrochemical method in four different kinds of electrolyte. The pure titanium metal (99.99%) with 0.8 cm in width and 2 cm in length was used as a substrate and it was subsequently etched by 2M HF for 1 minute before electrochemical deposition. Calcium phosphate film could form at a different current density for each kind of electrolyte as follows: 10 mA/cm2 for MCPM based aqueous solution, 20 mA/cm2 for MCPM based aqueous solution with ions addition, 10 mA/cm2 and 20 mA/cm2 for MCPM based 20%V/V ethanol and 50%V/V ethanol solution, respectively. …

Sintered Properties Of 409l Powder Compacts Influenced By Metal Powder Additives, O Coovattanachai, T Yodkaew, M Morakotjinda, N Tosangthum, R Krataitong, A Daraphan, B Vetayanugul, R Tongsri

Journal of Metals, Materials and Minerals

Sintering of powder compacts, prepared by admixing of 409L powder with 2-6 wt.% of copper and nickel powders was investigated. It was observed that the strength of the 409L-Cu specimens increased with increasing Cu content. In contrast, sintered density and elongation decreased with increasing Cu content due to swelling effect. When 2 wt.% of Ni powders were added, sintered density and strengths were maximized. When Ni contents higher than 2 wt.% , the decrease of sintered density and strengths were attributed to the number of pores left by the original sites of Ni powder particles.

Sintered Fe-Al2o3and Fe-Sic Composites, T Yodkaew, M Morakotjinda, N Tosangthum, O Coovattanachai, R Krataitong, P Siriphol, B Vetayanugul, S Chakthin, N Poolthong, R Tongsri

Journal of Metals, Materials and Minerals

The presence of non-reactive (Al2O3) and reactive (SiC) hard particles affected properties of sintered Fe-base composites. With the same compacting and sintering conditions, addition of Al2O3 particles caused reduction of sintered densities. Tensile strengths, elongation and hardness of the sintered Fe-Al2O3 materials decreased with increasing Al2O3 particle amounts. The presence of Al2O3 particles prohibited compacting and sintering processes of the Fe powder. In contrast, addition of SiC particles resulted in reaction between Fe and SiC particles. Sintered density of the sintered Fe-SiC composites was significantly lower than that of the sintered Fe-Al2O3 materials. However, tensile strengths and hardness, except elongation, …

Current Status Of Nanotechnology Consumer Products And Nano-Safety Issues, N Chuankrerkkul, S Sangsuk

Journal of Metals, Materials and Minerals

This paper is divided into 2 parts to present a review on nanotechnology consumer products ('Nanotech' products) and a current status on 'Nano-Safety' issue. The first part focuses on up-to-date information of 'Nanotech' products that were already on the market as reported by Project on Emerging Nanotechnologies of the Woodrow Wilson International Center for Scholars. There are more than 500 products for a variety of applications, among which health and fitness products are the largest category. The products in this group consist of clothing, cosmetics and sunscreens. Silver is the most commonly used material, followed by carbon in the forms …

Morphology Controlled Calcium Ortho Phosphates Induced By Chemical Additions Under Hydrothermal Reaction, D P. Kashima, E Kongkul, T Daopradubwon

Journal of Metals, Materials and Minerals

Morphology controlled calcium orthophosphates under hydrothermal reaction was achieved using saturated solution of monocalcium phosphate monohydrate (MCPM) as a starting material. MCPM saturated solution was hydrothermally treated at 180°C for 4 and 12 hrs. Citric acid as a chelating agent and a mixed solution of NaNO3 and NaF were individually added into the reactor. The morphologies, phases and microstructures of the obtained products were characterized by optical microscope (OM), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. Irregular shape crystals were obtained when a saturated solution of MCPM was autoclaved at 180°C for 4 hrs. Though citric acid was …

Reflection High-Energy Electron Diffraction Studies Of Indium Phosphide (100) And Growth On Indium And Indium Nitride On Silicon (100), Mohamed Abd-Elsattar Hafez

Electrical & Computer Engineering Theses & Dissertations

Study of the effects of atomic hydrogen exposure on structure and morphology of semiconductor surfaces is important for fundamental properties and applications. In this dissertation, the electron yield of a hydrogen-cleaned indium phosphide (InP) surface was measured and correlated to the development of the surface morphology, which was monitored by in situ reflection high-energy electron diffraction (RHEED). Atomic hydrogen treatment produced a clean, well-ordered, and (2x4)-reconstructed InP(100) surface. The quantum efficiency, after activation to negative electron affinity, and the secondary electron emission were shown to increase with hydrogen cleaning time. RHEED patterns of low-index InP(100) surface were modified by the …

The Four-Domain Development Diagram: A Tool For Designing Development-Centered Teaching, Linda Vanasupa, Trevor S. Harding, William L. Hughes

Materials Engineering

Research in education has brought to light the complexity of the learning process, demonstrating that students' development is influenced by a myriad of cultural and social factors, as well as the environment in which learning takes place. Engineering curricula, however, are primarily focused on teaching content knowledge, often resulting in a gap between what is taught and what is learned. We propose that shifting some of the focus onto the process of learning that occurs within the student and leveraging multiple known connections from educational psychology can result in more effective engineering education. Here we define “effective” engineering education as …

Enhancing Precalculus Curricula With E-Learning: Implementation And Assessment, Janet Callahan, Seung Youn Chyung, Joanna Guild, William Clement, Joe Guarino, Doug Bullock, Cheryl Schrader

Materials Science and Engineering Faculty Publications and Presentations

During Fall semester of 2007, a semester-long, quasi-experimental study was conducted at Boise State University to investigate the effectiveness of a systematically sequenced and managed, self-paced e-learning activity on improving students’ academic performance and motivation. A total of 125 students enrolled in 3 different sections of a Precalculus class participated in the study. The e-learning activity was implemented in 2 of the 3 sections as a required homework assignment. Students enrolled in one of the 2 selected sections were all engineering majors. The 3^rd section was a control group that did not use the e-learning activity. A pre-test, measuring …

Engineering Project Laboratory Modules For An Introduction To Materials Course, Stacy Gleixner, Elliot Douglas, Olivia Graeve

Faculty Publications

The final results of curriculum development under an NSF, CCLI-EMD sponsored project, “Development of Project-Based Introductory to Materials Engineering Modules” (DUE # #0341633) is discussed. A multi-university team of faculty developed five lecture and three laboratory modules for use in Introductory to Materials courses. This course is required by most engineering programs in the U.S., with an annual enrollment of 50,000 students.1 This freshman/ sophomore class is an ideal place to excite students about their engineering majors and expose them to real world engineering problems. PRIME Modules, Project Based Resources for Introduction to Materials Engineering, utilize modern materials science and …

The Effect Of Radiation On The Electrical Properties Of Aluminum Gallium Nitride/Gallium Nitride Heterostructures, John W. Mcclory

Theses and Dissertations

AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) were irradiated at low temperature and the temperature dependent changes to drain current, gate current, capacitance, and transconductance were measured. The results were compared to the charge control model of the drain current and trap-assisted tunneling model of the gate current to determine the source of the radiation-induced changes. AlGaN/GaN HFETs demonstrated threshold voltage shifts and drain current changes after irradiation. After electron and neutron irradiation applied at ~80 K, measurement of the drain current at this temperature showed an increase that saturated after 10¹³ electrons/cm² or 10¹⁰ neutrons/cm² due …

Protein Interactions With Mixed Poly(Ethylene Glycol)/Polyacrylic Acid Brushes, Zhenqing Li

All Theses

Tethered polymer chains that are grafted to a solid substrate by one chain end (polymer brushes) may be distinguished from other anchored polymer layers by the relatively high grafting densities gained. Potential uses of polymer brushes for interfacial modification to regulate interactions between proteins and substrates, such as drug delivery and protein separation, are widely recognized. Therefore, it is important to investigate interactions between proteins and surfaces modified with a polymer brush.
In this study, the 'grafting-to' method has been used to graft mixed poly(ethylene glycol) (PEG) and polyacrylic acid (PAA) brushes onto poly(glycidyl methacrylate) (PGMA)-modified silicon wafers/glass slides to …

Investigating A Natural Organic Binder As A Bitumen Substitute In Flexible Pavements, Karim Ahmed Abdel Warith

Archived Theses and Dissertations

No abstract provided.

Powder Rolling Of Cnt-Reinforced Aluminum Strips, Mostafa Abdel-Fattah El-Borady

Archived Theses and Dissertations

Multi walled carbon nanotubes (MWCNT) were added to aluminum powder (99.97% pure) to produce a composite material. Three mixing techniques were examined

1 Low energy mixing: Using a Turbula mixer with two different speeds 48 and 67 rpm.

2 High energy mixing: Using a ball mill without adding any balls in the mixing jars with two speeds 300 and 400 rpm.

3 Ball milling: Using the ball mill (with steel balls) to mix higher CNT weight fraction samples for the electrical resistivity tests.

The mixtures were packed in copper cans and rolled in a rolling machine to compact the mixture; …

Electrodeposition Of Sol-Gel Imprinted Films Modified Electrode And Its Application For 3,4-Dihydroxybenzoic Acids Determination, Gui-Lin Wang, Rong Wang, Xia-Qin Wu, Zong-Rang Zhang

Journal of Electrochemistry

The sol-gel molecularly imprinted films modified glassy carbon electrode was prepared by electrodeposition of tetramethoxysilane(TMOS) and phenyltrimethoxysilane(PTMOS) with chronoamperometry in the presence of template molecules 3,4-dihydroxybenzoic acid(3,4-DHBA) followed by extraction with ethanol.The modified electrode could successfully avoid the polymerization of oxidized 3,4-DHBA and the interference of 2,4-DHBA.A linear concentration response curve was obtained from 1.0 × 10^-5 mol·L^-1 to 8.0×10^-4 mol·L^-1,with the detected concentration limit of 5.0 × 10^-6 mol·L^-1.

Preparation And Photoelectrochemical Properties Of Fe-Doped Tio2 Nanotube Arrays, Jing Li, Lan Sun, Hui-Fang Zhuang, Cheng-Lin Wang, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The Fe-doped TiO₂ nanotube arrays were fabricated in Fe(NO₃)₃-HF mixing solutions by electrochemical anodic oxidation method,and characterized by FESEM,Raman,XPS and DRS.The effect of Fe concentratiions on photoelectrochemical property of the arrays was also investigated.The diameters and lengths of Fe-doped TiO₂ nanotube arrays were 50~90 nm and about 200 nm,respectively.Compared with the undoped TiO₂ nanotube arrays,the absorption edge of Fe-doped TiO₂ nanotube arrays appeared red shifting.The more Fe content,the larger red shifting,in addition,the photocurrent of Fe-doped TiO₂ nanotube arrays increased obviously.

The Effect Of Annealed Temperature On Properties Of Ru-Ir-Sn Oxide Anode Coatings, Lei Ji, Jun-Tao Wang, Li-Kun Xu, Wen-Bin Liu, Gui-Lin Xue

Journal of Electrochemistry

The anode coatings of Ru-Ir-Sn oxide were prepared by sol-gel method with different annealed temperatures.The influences of annealed temperature in properties of anode coatings were characterized by scanning electron microscope(SEM),energy dispersive X-ray detector(EDX),X-ray diffraction(XRD),potential of chlorine evolution,accelerated life,cyclic voltammetry and electrochemical impedance spectroscopy(EIS) tests.The results showed that the annealed temperature affected the morphology of coatings,while the electric quantities of cyclic voltammetry and double layer capacitances of anode coatings had a tendency to fall down and the potential of chlorine evolution and accelerated life had a tendency to increase as the annealed temperature increased.

Cyclic Voltammetry And In Situ Ftir Studies Of Cyanide Adsorption On Nanostructured Au Film Electrode In Alkaline Solutions, Chun-Hua Zhen, Chun-Jie Fan, Shi-Gang Sun

Journal of Electrochemistry

The adsorption of cyanide(CN^-) on electrodes of nanometer scale thin film of gold supported on glassy carbon(nm-Au/GC) in alkaline solutions were investigated using cyclic voltammetry and in situ FTIR spectroscopy.It has revealed that the electrodeposited nanostructured Au thin film exhibited AIREs(abnormal infrared effects) for CN^-adsorption,which manifested 3 nonlinear IR spectral features: inversion of the direction of CN^-band,enhancement of IR absorption of adsorbed CN-species(about 39.2 folds) and increase in the FWHM(full width at half maximum) of CN^-band.

Electrocatalytic Performance Of Pt/C And Pt/Wo3/C Catalysts For Methanol Oxidation, Yuan-Yuan Chu, Bing Wu, Ya-Wen Tang, Tian-Hong Lu, Ying Gao

Journal of Electrochemistry

The catalysts of Carbon supported Pt(Pt/C) and carbon supported Pt/WO₃(Pt/WO₃/C) were prepared with liquid phase reduction method.It was found that the catalytic activity and stability of the Pt/WO₃/C catalysts were increased with the addition of WO₃.When the atomic ratio of Pt and W was 1∶1,the best electrocatalytic performance of the Pt/WO₃/C catalyst for the methanol oxidation was obtained.This is attributed to the larger electrochemical surface area of Pt/WO₃/C and the weeker adsorption of CO towards the catalyst.

Synthesis And Electrochemical Characteristics Of Li[Li(0.167)Mn(0.583)Ni(0.25)]O2 Cathode Material, Ling-Yan Yu, Wei-Hua Qiu, Fang Lian, Jia-Yuan Huang, Xao-Li Kang, Wei Liu

Journal of Electrochemistry

The cathode material of Li[Li_0.167Mn_0.583Ni_0.25]O₂ was synthesized by low-heat solid state reaction.The results of XRD and FESEM indicated that the powders of the material were well crystallized with the uniform diameters ranging from 60 nm to 100 nm and could be indexed as α-NaFeO₂ structure(R3-m space). Galvanostatic charge-discharge tests showed that the electrode delivered the capacity of about 120 mAh/g with good cyclability when cycled in 2.5~4.4V at 0.5C. When the cut-off potential was set up to 4.6V, the cathode delivered much larger capacities with the maximum of 234 mAh/g. It was …

Direct Electrochemistry Of God On Glassy Carbon Electrode Modified With Mesoporous Carbon, Kun-Qi Wang, Lin Zhu, Wei Xing

Journal of Electrochemistry

Glucose oxidase(GOD) is immobilized on glassy carbon electrode mesoporous carbon by simple method.Cyclic voltammetric results indicated that on GOD of the modified electrode a quasi-reversible redox reaction took place(GCE) surface modified at a formal potential of-0.4294 V in 0.1 mol/L phosphate buffer solution(PBS)(pH 7.1).The electrochemical reaction consisted of a two-electron transfer coupled with a two-proton transfer.The GOD can completely catalyze oxidation of glucose via electron transfer intermedia of ferrocene monocarboxylic acid(FMCA) in saturated solutions with N₂.The bioactivity of GOD on the modified electrode with mesoporous carbon was obviously unattacked.

Carbon Nanotube Array Electrodes Based Supercapacitors With 3.5v Working Voltage, Hao Zhang, Gao-Ping Cao, Yu-Sheng Yang, Zhen-Nan Gu, Bin Xu, Wen-Feng Zhang

Journal of Electrochemistry

The carbon nanotube arrays(CNTA) were grown directly on the substrates of Ta and stainless steel by chemical vapor deposition.The button-like supercapacitors were fabricated based the CNTA electrodes.The electrochemical performance of CNTA based supercapacitors presentsed high working voltage(3.5 V),long cycle life,and good rate capability.The power and energy densities are were 928 kW·kg^-1 and 19 Wh·kg^-1,respectively(based on the mass of CNTA).

Electrochemical Performances Of Copper/Activated Carbon Composites, Lan-Ting Li, Qiang Xie, Wen Yan, Yan-Yan Wang, Wen-Wen Xing

Journal of Electrochemistry

The development and improvement of electrode materials can result in the enhancement of the performances of electrochemical capacitor.In this paper various copper/activated carbon composites were prepared in the presence of different amounts(from 0% to 40%) of copper nitrate from bituminous coal.Then different electrodes were prepared from copper oxide,activated carbon and copper/activated carbon composites,respectively,and were characterized by cyclic voltammetry,alternative current(AC) impedance,charge-discharge at constant current and maintenance of the self-potential.The results showed that the proper amount of copper in copper/activated carbon composites positively influenced the electrochemical performances of electrodes,and the capacitance of copper/activated carbon composites was larger than that of the total …

Electrochemical Performance Of C-Lifepo4 By Polyaniline Doping, Wei Wang, Li-Fang Jiao, Hua-Tang Yuan

Journal of Electrochemistry

The olivine LiFePO₄ cathode materials were synthesized using the solid state method in an inert atmosphere by doping polyaniline into the C-LiFePO₄.It was found that the electrochemical performance of polyaniline-doped C-LiFePO₄ slightly improved.At a low discharging rate(0.1C), the capability of(C-LiFePO₄)0.9(PANI)0.1 reached 164 mAh·g^-1.When the charge-discharge rate is increased to 0.5C and 1.0C,the showed capacities of 121.6 mAh·g^-1 and 110.1 mAh·g^-1 were obtained,respectively.

Preparation Of Zn-Ni Alloy Whisker By Electrochemical Method, Zhen-Hai Liang, Xi-Hua Xia

Journal of Electrochemistry

The Zn-Ni alloy whiskers were prepared by electrochemical method and were characterized by XRD, SEM and EDS methods. The results showed that Ni₅Zn₂₁ and Ni₃Zn₂₂ whiskers were obtained with the length of 2~4 μm and the diameter of 250 nm, thereby the rations of length/diameter fell between 8 and 16. The electrochemical behavior was investigated by cyclic voltammetry method simultaneously. A new method was provided on whisker preparation based on this work.

Synthesis Of Agv3O8 As High-Capacity Of Cathode Materials For Lithium Secondary Batteries Via A Soft Chemistry Technique, Xiao-Yu Cao, Tao Li, Ling-Ling Xie, Xiang-Yang Yan, Chi-Wei Wang

Journal of Electrochemistry

The layered cathode material of AgV₃O₈ has been prepared for the lithium secondary batteries via the soft chemistry technique. The so-synthesized powders were characterized by XRD(powder X-ray diffraction), SEM(scanning electron microscope) and LPSA(laser particle size analysis). The electrochemical property was investigated by the galvanostatic discharge-charge technique. The results indicated that the particale sizes of AgV₃O₈ prepared were small in the distribution of narrow range, which leads to high discharge capacity. Among them, the material synthesized at 400 ℃ displayed the first discharge capacity of 760.5 mAh/g.

Passivation Behaviors Of Mo, W Electrodes In Mgcl2-Kcl-Nacl-Cacl2 Molten Salt For Electrolysis Of Magnesium, Ye Chen, Ke Ye

Journal of Electrochemistry

The discharge process and passivation behaviors of Mg(Ⅱ) on cathode(Mo, W) in MgCl₂-KCl-NaCl-CaCl₂ molten salt system had been investigated by means of cyclic voltammetry and chronoamperometry. The composition of molten salt was MgCl(10%) + CaCl(20%) + NaCl(60%) + KCl(10%)(by mass) and the temperature of electrolysis was 725 ℃. The deposition potential of Mo was 37 mV more negative than that of W, while the peak current was sharper than Mo according to the voltammograms at 0.05 V/s, indicating that the passivation on Mo cathode is easier than W. The formation of MgO impurities during the electrolysis could …

Electroless-Deposition Synthesis Of Highly Active Ptru/C And Ptrusn/C As Anode Catalysts For Defc, Jing Zhu, Yi Su, Hua Ma, Fang-Yi Cheng, Zhan-Liang Tao, Jing Liang, Jun Chen

Journal of Electrochemistry

In this paper,the preparation,characterization,and ethanol electrocatalytic oxidation of Pt_0.5Ru_0.5/C and Pt_0.5Ru_0.15Sn_0.35/C electrocatalysts were reported.The electroless-deposition with sensitization-activation pretreatment was applied to prepare Pt_0.5Ru_0.5/C and Pt_0.5Ru_0.15Sn_0.35/C electrocatalysts. The XRD and TEM analyses showed that the as-prepared catalysts were composed of well-dispersed PtRu or PtRuSn nanoparticles with an average particle size of about 3 nm.The electrochemical measurements demonstrated that the as-prepared Pt_0.5Ru_0.5/C and Pt_0.5Ru_0.15Sn_0.35/C catalysts exhibited much enhanced peak current density for …

Performance Of Air Breathing Direct Methanol Fuel Cell Under Ambient Condition, Jian-Guo Liu, Jun Gu, Tao Yu, Zhi-Gang Zou, T.S Zhao

Journal of Electrochemistry

The performance of the passive DMFC was systematically investigated under an ambient condition by simulating a wide range of temperature and humidity in a high-quality environmentally controlled room.The results indicated that the performance of the passive DMFC was nearly independent of ambient humidity from 30% to 90% RH and water produced in the cathode was expelled mostly from the cell in a liquid state.Compared with the humidity,the ambient temperature has a significant effect on the performance of the passive DMFC.The power density of 30 mW·cm^-2 were obtained at 40℃,while only 10 mW·cm^-2 at 10 ℃.

Preparation And Electrochemical Capacitance Of Spherical-Like Polypyrrole Doped With Heparin Sodium, Hong-Yu Mi, Xiao-Gang Zhang, Su-Dong Yang, Xiang-Guo Ye

Journal of Electrochemistry

Spherical-like polypyrrole with an average diameter of 100 nm as the electrode material for supercapacitor was prepared by a self-assembly process with heparin sodium salt as the dopant at-10 ℃.The morphology and electrochemical properties were characterized by transmission electron microscopy(TEM),cyclic voltammetry(CV),galvanostatic charge/discharge and electrochemical impedance spectroscopy(EIS) measurements.The results showed that the polypyrrole doped with heparin sodium salt exhibited good capacitive behavior.The specific capacitance of single electrode was up to 338 F/g at 3 mA/cm².

Structure And Property Of Molecular Self-Assembled Membrane With Zirconium Ion, Tian-De Wang, Rong Wang, Xia-Qin Wu, Zhi-Gang Guo, Wei-Wei Ji

Journal of Electrochemistry

According to the complex interaction between dodecyl phosphonate and stainless steel surface as well as the zirconium ion,the self-assembled monolayer and double-layer dodecyl phosphonate modified 304 type stainless steel electrode were prepared.The electrodes were characteristiced by static contact angles and electrochemical polarization methods.The results suggested that the double-layer modified stainless steel electrode had better corrosion inhibition effect than the monolayer modified electrode.