Materials Science and Engineering Commons^™

Effect Of Temperature And Pressure On The Densification Of Titanium Silicide Compound, P Thapnuy, S Larpkiattaworn, T Luangvaranunt, J Ikeuchi

Journal of Metals, Materials and Minerals

Titanium silicide compound was synthesized from the mixture of titanium and silicon powder with atomic ratios of 60:40 and 70:30. The powders were mixed by ball milling and pressed by different methods: by using uniaxial pressing at 64 MPa, cold isostatic pressing (CIP) at 200 MPa, hot forging (HF) at 648 MPa, and hot pressing (HP) at 24 MPa. The samples were then sintered at 1300o C or 1600o C for 2 hours soaking time in argon atmosphere. The sintered samples were subsequently characterized for phase constitution using X-ray diffraction (XRD). Ti5Si3 was observed as main compound of mixtures with …

Effects Of Aluminium On Sintered Properties Of Cu-10wt%Sn Bearing, V Chobaomsup, T Luangvaranunt

Journal of Metals, Materials and Minerals

Self-lubricating bearings are one of the oldest industrial applications of porous powder metallurgy parts, dating back to the mid-1920s. They remain the highest part produced by the P/M industry. The objective of this research was to study the effects of sintering time, sintering temperature and ratio of adding aluminium on sintered properties of Cu-10wt%Sn bearing that was produced from powder metallurgy processing. Various physical and mechanical properties such as density, percentage of porosity and hardness were tested to elucidate the effect of processing parameters. Phase identification and microstructure were analyzed by X-Ray Diffractometer and optical microscope, respectively. Sintering times in …

Pickling Behavior Of Aisi 304 Stainless Steel In Sulfuric And Hydrochloric Acid Solutions, W Homjabok, S Permpoon, G Lothongkum

Journal of Metals, Materials and Minerals

Oxide scales as well as a Cr-depleted layer, which grows between the oxide scale and base metal, are formed on AISI 304 stainless steel surface during high temperature processing. Pickling is an important process which includes mechanical and chemical operations to remove oxide scales, Cr-depleted layers, and to recover the surface passivity. The multi-step pickling is commonly used because of its higher efficiency than a single step pickling. In this study, the multi-step pickling of AISI 304 stainless steel in HCl solution was investigated instead of H2SO4 solution for the first step of pickling. HF+HNO3 mixed acid is traditionally used …

Development Of An Aluminum Semi-Solid Extrusion Process, T Rattanochaikul, S Janudom, N Memongkol, J Wannasin

Journal of Metals, Materials and Minerals

Semi-solid extrusion process is a new forming process that is quite promising because the process requires lower forming pressure than conventional solid extrusion. In addition, semi-solid extrusion does not require large machines, which results in lower production costs. The aim of this article is to study the feasibility of an aluminum semi-solid extrusion process. The semi-solid technique selected for usage in this study was the Gas Induced Semi-Solid (GISS) process. The laboratory extrusion system was developed in this work. In the experiments, nitrogen gas was injected into aluminum melt for about 5 seconds. After that, the obtained semi-solid slurry was …

Development Of Layered Zn-Fe Coatings For Better Corrosion Protection, R S. Bhat, R Udupak, A C. Hegde

Journal of Metals, Materials and Minerals

In this research, the Zn-Fe coating having successive layers of alloys of two different compositions were developed alternatively on mild steel for better corrosion protection. The multilayer coatings, or alternatively, composition modulated alloy (CMA) coatings of different configurations have been developed, and their corrosion behaviors were evaluated by electrochemical DC and AC methods. The cyclic cathode current densities and numbers of layers have been optimised for peak corrosion stability of the coatings. Under optimal condition, the CMA coating having 300 layers, having about 67 nm average thickness was found to be approximately six times higher corrosion resistant than monolayer coating …

Effect Of Sintering On Microstructure And Properties Of Hydroxyapatite Produced By Different Synthesizing Methods, N Monmaturapoj, C Yatongchai

Journal of Metals, Materials and Minerals

The aim of this study is to investigate the effect of the sintering schedule on microstructure and properties of hydroxyapatite which is produced by different synthesizing methods. Hence, wet-chemical precipitation and solid-state reaction were performed to prepare nano-sized hydroxyapatite (HA) powders. Powders were then uniaxially pressed and sintered by varying temperatures and times. XRD and SEM were used to identify phases and morphology. Density and porosity of the sintered sample were determined using the Archimedes technique. Flexural strength was measured by a universal testing machine. The results show that density and strength could be improved by increasing the sintering temperature …

Hardness And Fracture Toughness Of Alumina-Based Particulate Composites With Zirconia And Strontia Additives, T Oungkulsolmongkol, P Salee-Art, W Buggakupta

Journal of Metals, Materials and Minerals

This project aims to study characteristics and mechanical properties i.e. hardness and fracture toughness of alumina matrix composite materials containing zirconia and strontium oxide. Two groups of composite specimen were fabricated: (i) Al2O3 matrix with 3 mol% Y2O3- ZrO2, varied from 10, 20, 30 and 40 vol%, and (ii) Al2O3 matrix with 2, 5, 10 and 15 vol% SrO added in the form of SrCO3. The powders were blended and then pressed into pellets. The compacts were pressureless sintered at 1600 o C for 2 hours in air. Density measurement of the sintered composites was carried out using liquid immersion. …

Preparation And Properties Of Superhydrophobic Cotton Fabrics, P Kampeerapappun, K Visatchok, D Wangarsa

Journal of Metals, Materials and Minerals

In this study, superhydrophobic cotton fabric was prepared by coating maleic-anhydride grafted poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-MA) triblock copolymer solutions containing calcium carbonate (CaCO3) particles. SEBS-g-MA solutions were prepared using single solvent (toluene and tetrahydrofuran (THF)) and mixed solvent (toluene: ethanol (EtOH) and THF: EtOH). Cotton fabrics were treated with the prepared solution using padding technique. All coated fabrics exhibited a water contact angle (WCA) of more than 100°. Optimum WCA values were observed when THF and 90:10 toluene: EtOH were employed. In case of CaCO3 particles addition, 6% W/V CaCO3 could impart the highest WCA value of 154°. However, the durability of …

Surface Modification Of Polyester Fabrics With Vinyltriethoxysilane, B Kusuktham

Journal of Metals, Materials and Minerals

Surface modification of polyester fabrics was studied aiming at improving the water repellency property. Vinyltriethoxysilane (VTES) was employed as surface modifying agent. Prior to application, VTES was prepared in aqueous emulsion using cetyltrimethylammoniun bromide (CTAB) as an emulsifying agent. The application of VTES emulsion was carried out using a padder and followed by curing at 150° C for 15 minutes. The result showed that the treated fabrics exhibited higher contact angle values when compared to untreated fabric, indicating an increase in water repellency property. It was believed that VTES was converted into silicone through siloxane network. The presence of a …

Preparation And Characteristics Of Galangal Essential Oil/Alginate Microcapsules, T Jiamrungraksa, S Charuchinda

Journal of Metals, Materials and Minerals

Galangal essential oil/alginate microcapsules were prepared by solidifying in liquid (orifice method) between sodium alginate and calcium chloride. The structure, morphology and also the thermal stability of the microcapsules were investigated by FT-IR, optical microscope, infrared moisture determination balance (IMDB) at 120°C for 2 hours. The galangal essential oil release content of microcapsules was estimated by measuring time course of weight of microcapsules determination by isothermal TGA at 37°C and 120°C. FT-IR spectral data confirmed the presence of galangal essential oil in the prepared microcapsules. An increase of sodium alginate concentration and oil content resulted in significantly higher average size …

Utilizing Copper(I) Catalyzed Azide-Alkyne Huisgen 1,3-Dipolar Cycloaddition For The Surface Modification Of Colloidal Particles With Electroactive And Emissive Moieties, Parul Rungta

All Dissertations

The development of charge–transporting and fluorescing colloidal particles that can be directly printed into electroluminescent devices may result in a broad impact on the use of electrical energy for illumination. The objective of this work was to design and synthesize electroactive & fluorescing colloidal particles; establish their optical, electronic, and thermodynamic properties; and transition them into a device format for potential applications. The original intended application of this work was to build “better” colloidally–based organic light emitting devices (OLEDs) by creating functional particles with superior electrical and optical performance relative to commercially available technologies, but through the course of the …

Production And Characterization Of Aramid Copolymer Fibers For Use In Cut Protection, Jeffrey Moreland

All Dissertations

High-performance fibers such as para-aramids are used extensively in gloves for cut protection. However, the inherent cut resistance of these fibers and the relationship between cut resistance and other material properties is not known. To better understand cut resistance at the material level, an experiment was conducted using a lab-scale wet spinning system to produce and characterize aramid copolymer fibers.
To facilitate the use of lab-scale equipment, the experiment was conducted as a four-factor split-plot response surface design. The four treatment factors studied were solvent concentration in the coagulation bath, the amount of salt in the coagulation bath, the degree …

Oxidation Of Cyclohexane And Ethylbenzene By Hydrogen Peroxide Over Co-Substituted Heteropolytungstate Catalyst, W Kanjina, W Trakarnpruk

Journal of Metals, Materials and Minerals

The tetrabutylammonium salt of Co-substituted heteropolytungstate, [(n-C4H9)4N]4 HPW11Co(H2O)O39.3H2O was synthesized and characterized. It was shown to be an active catalyst for the oxidation of cyclohexane and ethylbenzene. The oxidation reactions were performed using green oxidant hydrogen peroxide and acetonitrile as solvent. The major products of the oxidation of cyclohexane were cyclohexanone (K) and cyclohexanol (A). High selectivity towards K-A oil was achieved. At longer time cyclohexanol was converted to cyclohexanone. Ethylbenzene was also selectively oxidized to acetophenone. These oxidation reactions appear to be radical processes since they were totally inhibited in the presence of radical scavenger.

Versatile Route For Preparation Of Polydiacetylene/Zno Nanocomposites And Their Colorimetric Response To Ph And Ethanol, N Rungruangviriya, N Traiphol

Journal of Metals, Materials and Minerals

This contribution presents a simple method to prepare polydiacetylene(PDA)/ZnO nanocomposites, which can be utilized as active materials in sensing technology. The ZnO nanoparticles, which constitute of Zn-OH2 + , Zn-OH and Zn-O- groups at their surfaces, function as nano-substrates for self-assembling of diacetylene monomers, 10,12-pentacosadiynoic acid (PCDA), in aqueous medium. Photopolymerization of the assemblies yields poly(PCDA)/ZnO nanocomposites with core-shell structure. Strong interactions between the active groups at ZnO surface and carboxylic head groups of poly(PCDA) promote chain ordering and reduce segmental dynamics of poly(PCDA) in the nanocomposites. The existence of strong interfacial interaction drastically affects the colorimetric response behavior of …

Study On Flame Retardancy And Anti-Dripping Of Polyester Fabric Treated With Bentonite, Diammonium Hydrogen Phosphate And Aluminium Hydroxide, P Lerdkajornsuk, S Charuchinda

Journal of Metals, Materials and Minerals

The purpose of this research was to improve flame retardancy and anti-dripping of polyester fabric by using bentonite, 3% (w/w) diammonium hydrogen phosphate (DA) and 5, 10% (w/w) aluminium hydroxide (Al(OH)3) via pad-dry technique. The burning behavior of the treated polyester fabric was investigated according to ASTM D1230. The results showed that 10wt% of bentonite alone were capable of imparting anti-dripping. Nevertheless, the preparation of the slurry of bentonite (>10% (w/w)) caused high viscosity leading to difficulties for the preparation and finishing process. Thus, the addition of 4% (w/w) of sodium chloride (NaCl) to the suspension of bentonite (up …

Analyzing The Impact Of Reactive Transport On The Repository Performance Of Triso Fuel, Gregory Schmidt

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the largest determiners of the amount of electricity generated by current nuclear reactors is the efficiency of the thermodynamic cycle used for power generation. Current light water reactors (LWR) have an efficiency of 35% or less for the conversion of heat energy generated by the reactor to electrical energy. If this efficiency could be improved, more power could be generated from equivalent volumes of nuclear fuel. One method of improving this efficiency is to use a coolant flow that operates at a much higher temperature for electricity production. A reactor design that is currently proposed to take advantage …

Chemical And Electronic Structure Of Surfaces And Interfaces In Compound Semiconductors, Sujitra Pookpanratana

UNLV Theses, Dissertations, Professional Papers, and Capstones

The interface formation between two different materials is important in applications for optoelectronic devices. Often, the success or performance of these devices is dependent on the formation of these heterojunctions. In this work, the surface and interfaces in such materials for optoelectronic devices are investigated by a suite of X-ray analytical techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), and X-ray emission (XES) spectroscopies to provide novel insight.

For the group III-nitrides (e.g., AlxGa1-xN) used in many light emitting devices, a significant challenge exists to form an Ohmic contact. The electron affinities and band gaps of GaN and …

Transient Fluid Flow Phenomena During Continuous Casting: Part I-Cast Start, Yufeng Wang, Lifeng Zhang

Materials Science and Engineering Faculty Research & Creative Works

This work presents a three-dimensional numerical simulation of transient fluid flow phenomena during continuous casting of steel. in the Part I, the process of cast start was investigated. Cast start involved the filling process and the caster start process. in the filling process, molten steel was continuously filled into the mold cavity with surrounding mold walls and a dummy bar head at the bottom. to simulate the interface between the molten steel and the air, an algorithm of volume of fluid has been employed. in the cast start process, the dummy bar was gradually dragged out with a low casting …

Transient Fluid Flow Phenomena During Continuous Casting: Part Ii-Cast Speed Change, Temperature Fluctuation, And Steel Grade Mixing, Yufeng Wang, Lifeng Zhang

Materials Science and Engineering Faculty Research & Creative Works

Many complicated phenomena are associated with transient stages during the continuous casting process, especially inside the casting mold cavity. a deep understanding of the phenomena and optimized control over the process ensure the high-quality product and low costs. This work presents a three-dimensional numerical simulation of transient fluid flow phenomena during steel continuous casting. in the Part II, the process of casting speed change (increase or decrease), temperature fluctuation, and steel grade mixing in a slab mold were investigated. the phenomena, such as flow pattern, inclusion removal fraction, temperature variation, top surface profile, and steel transportation, were addressed to evaluate …

A Simple Model To Calculate Dendrite Growth Rate During Steel Continuous Casting Process, Mujun Long, Lifeng Zhang, Fei Lu

Materials Science and Engineering Faculty Research & Creative Works

In the current paper, the relationship between the casting speed and the dendrite growth during steel continuous casting process was studied; and a simple mathematical model to calculate the primary dendrite growth rate according to the casting speed was developed. the model was used to predict the distribution of the dendrite growth rate along width direction and casting direction during a continuous casting process, indicating a dendrite growth rate of 0.1-3.0 mm/s, which is much higher than that in regular ingot casting. the dendrite growth rate fluctuates along casting direction because of the different cooling intensity in each zone of …