Materials Science and Engineering Commons^™

Surface Titration Of Colloidal Alpha-Alumina, J. W. Ntalikwa

Tanzania Journal of Engineering and Technology (TJET)

The surface charge density (σ₀) of colloidal alumina (α-Al₂O₃) suspended in 1:1 electrolytes (NaCl, NaNO₃, CsCl and CsNO₃) at different electrolyte concentration (c₀) was determined using acid-base titration. The data were described in terms of the Triple Layer Model (TLM) of electric double layer. It was observed that the polarity of σ₀ could be varied through a point of zero charge (PZC) by varying the pH of the suspension. The PZCs were observed to occur at pH = 7.8 ± 0.1, 7.6 ± 0.2, 8.5 ± 0.1 and 8.3 ± 0.1 in NaCl, NaNO₃, CsCl and CsNO₃, respectively. It was …

The Inclusion Behaviothe Inclusion Behavior Of Sodium Compounds In Sub-Micron Particles Formed During Coal Combustionr Of Sodium Compounds In Sub-Micron Particles Formed During Coal Combustion, Iddi Mkilaha

Tanzania Journal of Engineering and Technology (TJET)

During combustion of coal, biomass and sewage sludge, metallic compounds especially alkali metals such as sodium and potassium vaporize and form fumes which are emitted with the exhaust gases. These fumes are corrosive to the turbine blades of power plants. To minimize corrosion, efforts have been made to control the condensation phase of these metals. In this study, the evolution and inclusion of sodium in sub-micron particles was investigated using a drop tube furnace and a low-pressure impactor (LPI). Four types of coal with different chemical properties were tested. The results suggest that a reaction-controlled mechanism and nucleation via chemical …

Salt Balance, Fresh Water Residence Time And Budget For Non-Conservative Materials For Makoba Bay During Wet Season, As Ngusaru, Aj Mmochi

Tanzania Journal of Science

Water and salt budgets suggest that in order to balance the inflow and outflow of water at Makoba bay, there is net flux of water from the bay to the open ocean during wet season. Residual salt fluxes between the bay and the open ocean indicate advective salt export. Exchange of water between the bay with the open ocean plays a role of replacing exported salt via mixing. Calculated freshwater residence time for the bay is 63 days during wet season. Budget results for non-conservative materials indicate net DIP flux from the ocean to the bay and a net DIN …

Apparatus And Method For Dispersing Nano-Elements To Assemble Device, Craig A. Grimes, Elizabeth Dickey

Chemical and Materials Engineering Faculty Patents

An apparatus for dispersing a first plurality of conductive elongated nano-elements distributed within a carrier-fluid to assemble a conductive device made of a first charge-receptive area of a support surface to which at least one nano-element has attached, including: a nozzle through which the elongated nano-elements are directed such that the nano-elements pass through an electromagnetic field for imparting a preselected charge thereto, and toward at least the first charge-receptive area. The charge-receptive area is given a charge such that it attracts a first end-portion of one of the nano-elements. Also, a method of assembling a conductive device. Steps include: …

Magnetic Transitions In Disordered Gdal2, D. S. Williams, Paul M. Shand, Thomas M. Pekarek, Ralph Skomski, Valeri G. Petkov, Diandra Leslie-Pelecky

Materials Research Science and Engineering Center: Faculty Publications

The role of disorder in magnetic ordering transitions is investigated using mechanically milled GdAl₂. Crystalline GdAl₂ is a ferromagnet while amorphous GdAl₂ is a spin glass. Nanostructured GdAl₂ shows a paramagnetic-to-ferromagnetic transition and glassy behavior, with the temperature and magnitude of each transition dependent on the degree and type of disorder. Disorder is parametrized by a Gaussian distribution of Curie temperatures T_C with mean T_C and breadth Δ T_C. A nonzero coercivity is observed at temperatures more than 20 K above the highest T_C of any known Gd-Al phase; however, …

Adoption Of Variable Rate Technology, Isti Surjandari, Marvin T. Batte

Makara Journal of Technology

Site Specific Management (SSM), which also variously referred to as Variable Rate Technology (VRT), is an emerging technology that enables producers to make more precise input application decisions based on soil and field characteristics. This study analyzes factors influencing the adoption of VRT for fertilizer application for cash grain production in Ohio. Results show that producer and field characteristics might influence the adoption decision on various SSM components differently. It also provides insight as to the sequence of adoption of SSM component technologies and how this sequence might differ for producers of differing characteristics.

Study On Electrochromic Effect Of Polyaniline Film, Lienda Handojo, Junus Simangunsong

Makara Journal of Technology

Study on Electrochromic Effect of Polyaniline Film. The light transmission factor of an electrochromic film changes reversibly with the application of an electrical voltage. Thereby the transparent film becomes reversibly opaque so that it may be used to control light transmission. In this paper the results of a study on polyaniline film as an electrochromic active material is reported. Polyaniline looks yellow transparent in the reduced state and turns to green-blue at its oxidized state. The electrochromic device considered in this paper was fabricated in planar configuration of ITO glass − polyaniline film − electrolyte − ITO glass which involved …

Role Of K3-Xhxpw12o40 As A Catalyst In Selective Catalysis Of Methylamine Synthesis From Ammonia And Methanol, Mohammad Nasikin

Makara Journal of Technology

Role of K3-xHxPW12O40 as a Catalyst in Selective Catalysis of Methylamine Synthesis from Ammonia and Methanol. Synthesize of methylamine from methanol and ammonia was studied in this research work using a partially potassium heteropoly salt (K3-xHxPW12O40 abbreviated as KPW) as a catalyst. KPW was prepared from heteropoly salt and potassium carbonate by using ion exchange method. The reaction was conducted at 600 ~ 800K and at the atmospheric pressure. Reactor used was a continue flow reactor with W/F=0,1~0,9g-kat.mnt./cc.Concentration of reactants and products were analyzed by gas chromathography while catalyst structure was observed by XRD (X-ray diffraction). Isothermal adsorption method was …

Identification Of The First Limiting Amino Acid In Cooked Polished White Rice Fed To Weanling Holtzman Rats, Mellova Masrizal, J. B. Lamb

Makara Journal of Technology

Forty-eight male weanling rats (91 g) were utilized to study the nutritional adequacy of cooked polished white rice. Rats were individually housed, and allowed ad libitum access to one of six treatment diets. Treatment diets were 1) polished white rice plus 10% casein and 0.18% methionine, CAS, 2) polished white rice, WHR, 3) polished white rice plus 0.45% lysine, LYS, 4) polished white rice plus0.40% methionine, MET, 5) polished white rice plus 0.30% threonine, THR, 6) polished white rice plus 0.45% lysine, 0.40% methionine, and 0.40% threonine, COM. Rice was cooked prior diet formulation using a 3 to 1 ratio …

Application Of Tabu Search Algorithm In Job Shop Scheduling, Betrianis Betrianis, Putu Teguh Aryawan

Makara Journal of Technology

Application of Tabu Search Algorithm in Job Shop Scheduling. Tabu Search is one of local search methods which is used to solve the combinatorial optimization problem. This method aimed is to make the searching process of the best solution in a complex combinatorial optimization problem(np hard), ex : job shop scheduling problem, became more effective, in a less computational time but with no guarantee to optimum solution.In this paper, tabu search is used to solve the job shop scheduling problem consists of 3 (three) cases, which is ordering package of September, October and November with objective of minimizing makespan (Cmax). …

Alum And Pacl Coagulation, Winarni Winarni

Makara Journal of Technology

Alum and PACl Coagulation. Coagulation occurs by interaction of aluminum hydrolysis products with the contaminant such as colloidal particles. It is necessary to consider the different aluminum species that may present during specific conditions, since the mechanism of turbidity removal is dependent upon them. PACl consists of preformed aluminum hydrolysis products, which are stable below pH 6 and less sensitive than in situ hydrolysis product, alum. The benefits of PACl relative to alum have been investigated as a function of pH and Al dosages. Specific conditions and aluminum species that exist during the certain mechanisms of coagulation are discussed. Results …

The Selection Of Materials For Roller Chains From The Perspective Of Manufacturing Process, Rahmat Saptono

Makara Journal of Technology

The selection of materials for an engineering component is not only requested by its design function and shape, but also the sequence through which it is manufactured. The manufacturing operation of roller chains involves drawing and trimming processes aimed at producing semi-finished chain drives component with a well-standardized dimension. In addition to final combination of properties required by design constraints, the ability of materials to be formed into a desired shape and geometry without failure is also critical. The objective of materials selection should therefore involve additional attributes that are not typically accommodated by the standard procedure of materials selection. …

An Economic Analysis Of Variable Rate Technology, Isti Surjandari, Marvin T. Batte, Mario J. Miranda

Makara Journal of Technology

Variable Rate Technology (VRT) offers an opportunity to improve production efficiency by allowing input applications to fluctuate in response to spatial variations in soil characteristics and nutrient levels. Society may also benefit from reduced negative externalities, such as surface and groundwater contamination, from input applications. Using a dynamic spatial model, this study examines how the interaction among variability, spatial autocorrelation, and mean level of soil fertility affects optimal sampling density and the economic gains from VRT. VRT was found to be profitable under selected conditions, and the optimal grid size will vary with these conditions. In the case where variability …

Superplastic Forming Of Micro Components, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

A method for forming a miniaturized shaped component. Bulk superplastic material is contacted with a flat rotating surface of a rotating tool to frictionally heat the bulk superplastic material with the bulk superplastic material positioned between the flat rotating surface of the tool and a micro fabricated tool die. The bulk superplastic material is forced into the microfabricated die once the bulk superplastic material is heated to a temperature between a glass transition temperature and a crystallization temperature.

Investigation Of Electrical Properties And Structure Of Vacuum Evaporated C60 Films, Angiras D. Pandya

Masters Theses

C₆₀ is an important electronic material and its properties can be tuned by thermal annealing process and solid phase crystallization process. These properties were investigated as a function of thermal annealing temperature and solid phase crystallization. However there is no systematical study on annealing effect and Solid Phase Crystallization of C₆₀ films. In this study, the effect of thermal annealing on formation of nanocrystalline C₆₀ thin films were investigated for annealed samples and solid phase crystallized samples. The C₆₀ films described here were prepared by vacuum thermal evaporation method. The structural properties of C₆₀ films …

Effect Of Crucible Diameter Reduction On The Convection, Macrosegregation, And Dendritic Morphology During Directional Solidification Of Pb-2.2 Wt Pct Sb Alloy, Jun Chen, Surendra N. Tewari, G. Magadi, H. C. Degroh Iii

Chemical & Biomedical Engineering Faculty Publications

The Pb-2.2 wt pct Sb alloy has been directionally solidified in 1, 2-, 3-, and 7-mm-diameter crucibles with planar and dendritic liquid-solid interface morphology. For plane front solidification, the experimentally observed macrosegregation along the solidified length follows the relationship proposed by Favier.([17,18]) Application of a 0.4 T transverse magnetic field has no effect on the extent of convection. Reducing the ampoule diameter appears to decrease the extent of convection. However, extensive convection is still present even in the 1-mm-diameter crucible. An extrapolation of the observed behavior indicates that nearly diffusive transport conditions require ampoules that are about 40 mum in …

Hot Melt Inks For Rotogravure-Formulation, Printability And Rheology, Hrishikesh Shreeram Bhide

Masters Theses

A new generation of "Hot melt inks for Rotogravure" was formulated. They melt during heating and reach printable viscosity between 75° C and 130° C, depending on formulation. After printing onto substrate, they solidify. Selections of the best formulations were done based on ink rheology, and print analysis. The formulated inks were also printed on the Moser sheet-fed proofing press .. The rheological data indicated that hot melt inks (without viscosity modifier) have viscosity in the range of 10°-10¹ Poise at 95°C. After printed on a laboratory gravure K-Proofer, the inks showed good reflective density (0.90 - Yellow, 1.30 …

Design Of Asphalt Concrete Mixtures For Pavement Maintenance And Rehabilitation, Mubarak Bakheet Gaith Al-Falahi

Theses

The main objective of the thesis is to develop a knowledge base for the design of asphalt concrete mixtures suiting various types and causes of pavement distress and to develop supporting guidelines for the selection of aggregate types, gradation and binder contents for desirable mixture properties.

To achieve this objective, a two-level model was developed. The upper-level is a Factorial Experimental Design Model (FEDM) for the pavement condition evaluation. It can be used as a prediction tool to estimate the Pavement Condition Index (PCI), and determine the percentages of the types of distresses (Load, Environmental, Others). The upper-level model was …

The Effect Of Non-Stoichiometry On The Structure Of La-Ni And La-Ni-Ga Alloys, Pertrice Auguste Wethey

Masters Theses

Non-stoichiometric samples of the AB₅ system defined by the formula La_1-yNi_5+2y and LaNi_5+2xGa_1-x were cast using an arc-melting furnace. The samples were then analyzed to determine their lattice parameters and phases present using XRD. They were then heat-treated to produce homogeneous compounds and quenched with the intention of retaining high temperature compositions. Following the heat-treatment, the alloys underwent XRD again as well as SEM/EDS. The XRD information was analyzed using Rietveld refinement and the elemental data derived from the EDS was used to ascertain the compositions were statistically akin to the weighed values. …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Fourth Quarterly Report 09/01/2003-11/30/2003, 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 …

Pitting Characteristics Of Cu-50/60ni Alloys In Nacl Solution, Jie Li, Yan Niu, Shi-Zhe Song

Journal of Electrochemistry

The pitting behavior of nanocrystalline Cu-50/60Ni and cast Cu-50/60Ni alloys in different concentration of NaCl solutions has been investigated using various electrochemical methods. A logarithmic dependence of the passive breakdown potential (E_b), which is established using dynamic potential scan technic, on the chloride concentration was obtained for both alloys. The study on pitting propagation of both alloys was carried out using potential step chronocurrent method. As long as pits initiate on both alloys, the pits on nanocrystalline Cu-Ni alloys develop faster than those on cast alloys.

The Current Fluctuations Of Carbon Steel In Nano2-Nacl Solutions, Yu-Ming Tang, Yu Zuo

Journal of Electrochemistry

The characteristics of current fluctuations of A3 carbon steel in NaNO₂-NaCl solutions were studied with potentiostatic and potentiodynamic polarization methods. The steel remained stable passivation in 0.1 mol/L NaNO₂ solution without Cl^-. After NaCl was added in to the solution, current fluctuations with a characteristic of quick increase and slow decrease occurred, indicating quick dissolution and slow re-passivation of the metastable pits. The metastable pitting may cause accumulated corrosion damage around certain area and result in observable pits. With the increase of chloride concentration, the occurring potential for metastable pits Em rised, and peak values …

Preparation And Characterization Of Y-Type Carbon Nanotubes By Using Anodized Alumina Oxide (Aao) Template, Jing Zhang, Quan-Yong Gao, Yong Yang

Journal of Electrochemistry

In this work, potential-modulation method was used in two-step anodization process to make an AAO template with Y-type nanochannels. Then Y-type carbon nanotubes with controlled length and branch angle were prepared in the template based on chemical vapor decomposion (CVD) method with Co particles as catalyst and C₂H₂ as carbon source. The Y-type nanotube branches exhibit the angle distribution ranging from 20° to 120°. The results demonstrated that the oxidation potential should be responsible for the angles and length of the branches. Short pulse and high oxidation potential will result in the short and dense nanotube branches.

Study On The Gas Generation In Different Charging Voltage During Formation Process In Polymer Lithium-Ion Battery, Li Huang, Ming-Gang Jin, Hui-Qun Cai, Ming-Sen Zheng, Quan-Feng Dong, Jin-Kua You, Zu-Geng Lin

Journal of Electrochemistry

The gases of polymer lithium-ion battery (PLI) generated under different voltages during the first charging process were examined by means of gas chromatography (GC), and the mechanism of the gas generation was discussed. The electrolyte used in batteries was 1 mol/L LiPF₆-EC～DMC～EMC=1∶1∶1(in volume). The results showed that when the charging voltage is less than 2.5 V,  the main component of generated gases are H₂ and CO₂, and when the charging voltage is 2.5 V, EC begins to decompose. Due to the decomposition of EC, the main generated gas is C₂H₄ when the …

Electrochemical And In-Situ Scanning Tunneling Microscopy Studies On The Sb Underpotential Deposition On Cu Single Crystal Electrodes, Ji-Hong Wu, Jia-Wei Yan, Jing Tang, Wen-Yun Hu, Bing-Wei Mao

Journal of Electrochemistry

We report electrochemical and in-situ STM studies on Sb UPD onto Cu(111) and Cu(100) electrode surfaces in HClO₄ and H₂SO₄ solutions. The results indicate that the electrode surface structure as well as anion can considerably influence Sb UPD. Sb UPD on Cu(100) forms open adlayer structures, which is accompanied by surface alloying due to the more open structure of the (100) surface, On Cu(111), a more compact Sb adlayer is formed instead. Anion adsorption influences the dynamics as well as the adlayer structure of Sb UPD. Owing to the strong adsorption of SO₄^2-, …

Application Of Hydrogen-Storage Alloy Electrode In Electrochemical Reduction Of Glucose, Hui Chen, You-Gen Tang, Zheng Tang

Journal of Electrochemistry

Electrolysis of glucose was performed at constant potential using hydrogen-storage alloy as catalytic reduction electrode. It was found that the superficial treatment and activation of hydrogen-storage alloy powder had obvious effects on improving the current efficiency of sorbitol. Under the optimums, current efficiency of sorbitol by electrolyzing glucose was over 94%. The yield of sorbitol was over 80%, the lifespan of electrode was tested and analyzed, the ways of regeneration were discussed.

The Study Of Green Corrosion Inhibitors For Mild Steel 907 In Natural Seawater Environment, Ping Gong, Min Du, Qing-Zhang Wang, Zhen-Jun Mu

Journal of Electrochemistry

Nine green compounds, including calcium gluconate, zinc gluconate, zinc sulfate, garlic, ACUSOL 445N, OS-15, APG, OCTA and STPP were selected according to the methods of molecule design and function groups prune. The functions of combined corrosion inhibitors mixed by the compounds mentioned above for mild steel in seawater were studied in this work using the methods of polarization curve and weight-loss.The best weight ratio and distinct synergistic effect of calcium gluconate, zinc sulfate and OCTA were studied by Latin experiment. The afgereffects of the best weight ratio corrosoin inhibitor were studied by subsection experiment. In this way, a kind of …

Preparation And Properties Of The Composite Microporous Pvdf-Hfp/Sio2 Based Polymer Electrolytes, Bao-Wen Zhang, Lu Qi, Hui Hen, Xiao-Hui Zhu, Li-Yan Liu, Yun-Xiang Ci

Journal of Electrochemistry

Microporous PVDF-HFP/SiO₂ film were prepared using a solvent/nonsolvent method-phase inversion method and the volatile plasticizers DMC, DEC or PC. The conductivity of the films increased pore volume measured by a nonsolvent uptake method. The conductivity of 1.86×10^-3 S⋅m^-1 were obtained using the liquid electrolyte LiPF₆(1 M) in EC/DMC (1:1).

Optimizing Catalyst Layer Composition Of Pemfc By Orthogonal Method, Ming-Hua Wang, Xin-Jian Zhu, Guang-Yi Cao, Sheng Sui, Qing-Chun Yu, Ming-Ruo Hu, Zheng-Yu Fan

Journal of Electrochemistry

The optimal composition of catalyst layer in a PEMFC electrode was studied through orthogonal method. It was showed that the performance of hydrophilic electrodes, in which there is no PTFE in the catalyst layer, were more favorable than that of hydrophobic electrodes. According to this condition, the power density of PEMFC attained 0.37 w·cm^-2 when the Nafion loading was 1.4 mg·cm^-2, and the Pt loading was 0.4 mg·cm^-2 in the catalyst layer, using H₂ as fuel and air as oxidant both at atmospheric pressure. Additionally, the results showed that increasing Pt loading in Pt/C catalyst …

The Study On Carbon Nanotube-Loaded Pt Catalysts For Proton Exchange Membrane Fuel Cells, Hong Zhu, Feng-Juan Ge, Xiao-Hong Kang, Yu-Guo Yang, Yun-Hua Xu

Journal of Electrochemistry

Carbon nanotube-supported-platinum (Pt/CNTs) and carbon-supported-platinum (Pt/C) catalysts were synthesized by in-situ chemical reduction. They were analyzed using TEM and XRD, then made into electrodes to be part of assemable PEMFC for the performence tests. The resulted show that Pt clusters in both catalysts are of small particle size (about 4nm), and Pt/CNTs exhibits a higher catalytic activity than Pt/C.