Current Nanoscience - Volume 10, Issue 1, 2014

Sintered bodies of TiO2nanopowders were fabricated by magnetic pulsed compaction (MPC) and subsequent 2 step sintering in this study and then, the effect of micro Ti and P-25 nano TiO2 powder addition on density, shrinkage and hardness was investigated. The optimum processing conditions in order to find the maximum density, hardness and shrinkage were found to be 0.5~0.7 GPa MPC pressure and 1450°C sinte Read More

Polycrystalline copper nanoparticles were synthesized from copper chloride dihydrate solution using the liquid phase plasma reduction method. A bipolar pulsed power supply with tungsten electrodes was used to generate discharge in the aqueous solutions. While large size of dendrite-shaped copper nanoparticles were mostly observed in the initial stage and particle size decreased with discharge time. The particles were dispe Read More

Used mainly in industries manufacturing secondary battery, display, LED, semiconductor, and other state-of-the-art products, rare earth elements (REEs) remain in demand and such demand has increased drastically. However, due to the lack of alternative materials and recycling technologies for REEs, many countries encounter difficulty in acquiring REEs. As part of the efforts to secure REEs, some studies have developed wet Read More

Using an a–InGaZnO(amorphous-IGZO) n-type semiconducting material, a vertically operating two terminal metalsemiconductor- ferroelectric-metal (MSFM) non-volatile resistive switching structure has been investigated. PZT thin film of composition Zr/Ti=10/90 was prepared by spin-coating method on the Pt/Ti/SiO2/p-Si(100) substrate, and 50 nm thick a-IGZO semiconductor thin film was deposited as a resistive layer Read More

This study attempted to manufacture Cu-In and Cu-Ga coating materials via the cold spray deposition (as a new process for sputtering target material) and to investigate the material’s applicability as a sputtering target for solar cell. To examine the microstructural and property changes made to those coating layers, purity, density, hardness, and porosity were measured. The results showed that coating layers of Cu-In an Read More

The need for composites has been growing in various industries because it has high mechanical properties for weight as well as superior stiffness and strength. The composites addressed in this study are multi-pore aluminum foam and honeycomb whose have excellent impact energy-absorption capability. In this study, impact tests of aluminum foam and honey core sandwich composite with porous core are conducted Read More

In order to find an effective method to increase the coercivity of Nd-Fe-B magnets using less Dy quantity, an ordinaryprocessed Nd-Fe-B sintered magnet was treated with dysprosium-compound suspension in this work. After the magnets were prepared by a normal sintering process, they were cut into the size of 10 x10 x5 mm3 pieces and then dipped in 20 % DyF3 suspension and 20 % DyHx suspension, for one minute, so Read More

Microwave sintering has emerged in recent years as a promising technology for faster, cheaper and eco-friendlier processing of a wide variety of materials, which are regarded as significant advantages against conventional sintering procedures. The present investigation describes a technique for sintering two different ceramic materials by microwave heating: alumina-15vol.% zirconia and hydroxyapatite nanopowders. The res Read More

The oxidation behaviors of Ti powder thermal spray coated Mo-Si-B alloys have been investigated in order to identify the underlying mechanism for the effect of precursor Ti coatings on Mo-Si-B alloys. Pure Ti powder was thermally sprayed on the two phase alloy (Mo (solid solution)+T2(Mo5SiB2)) fabricated by arc melting elemental components. The oxidation tests performed at 1100 °C show that the Ti po Read More

In this study, the mechanical properties and hot extrusion of carbon nanotubes (CNTs)-reinforced Mg (AZ31) based composite were investigated. To improve the mechanical properties of the Mg alloy AZ31, CNT /AZ31 composites were fabricated by mechanical alloying and hot extrusion process. Then, extrudates of these composites were formed using a hot-extrusion process. The conditions to prepare the extruded specimens, w Read More

The core structures of future nuclear systems require tolerance to extreme irradiation, and some critical components, for example, the fuel cladding in Sodium-cooled Fast Reactors (SFRs), have to maintain mechanical integrity to very high doses of 200 – 400 dpa at high temperatures up to 700 °C. The high Cr nanostructured ferritic alloys (NFAs) are under intense research worldwide as a candidate core material. Althoug Read More

The mechanical properties of automobile bevel gears manufactured by carburized guenching process are evaluated by using a finite elements method. The gear teeth of super, helical, and warm gears typically have constant cross sections and the same module, which results in the same frictional wear and stress. Bevel gears, however, are of a cone shape and thus the cross section of gear tooth change in the axial directi Read More

Wire cutting Electrical Discharge Machine (Wire EDM) uses the electrical discharge heat to cut the work piece with thin wire of brass or stainless steel by electrical discharge heat. The electrode and the work piece are melted and the cutting fluid between the electro and the piece is evaporated with burst. The melted material is spread in the shape of very tiny sphere chip. By the abrupt heating and cooling on the cut Read More

This study aims to understand the changes in mechanical properties when WC-7.5wt%Co and WC-12wt%Co compositions were experimented with various mixing, milling and consolidation conditions. Magnetic Pulsed Compaction (MPC) was used to consolidate WC-7.5wt% Co and WC-12wt% Co powders where high-energy ball milling with varying duration was employed for generating various powder types. Mechanically alloyed Read More

In this study, eco-friendly Pb-free Bi2O3–B2O3–ZnO glass frits were selected as an inorganic additive for the Al paste used in Si solar cells. The effect of glass chemistry on the electrical property of the Al electrode and on the cell performance was investigated. The results showed that as the molar ratio of ZnO to B2O3 increased, the glass transition temperature and softening temperature decreased because of the reduced g Read More

We synthesized Y2O3-reinforced nickel-matrix nanocomposites by mechanical alloying of Ni-Y2O3, Ni-Y, Ni-NiO-Y and Ni- CuO-Y powders. Mechanical alloying of constituent powder mixtures resulted in a complete dissolution of yttrium or Y2O3 in nickel, forming a nickel-based solid solution. However, undesirable oxides such as NiO easily formed after a prolonged milling and subsequent sintering even in an inert gas atmosph Read More

This work was conducted to establish an electrochemical noise (EN) measurement combined with a direct-current potential drop (DCPD) method, namely, an EN-DCPD technique, for in-situ monitoring of nano- or micro-scale crack initiation and the propagation of primary water stress corrosion cracking (PWSCC) of nickel based alloys, and to investigate its underlying mechanism. The EN signals of the potential and current were Read More

A model gas that mimics the syngas produced from gasification of municipal solid waste was applied, for the first time, to the synthesis of methanol over commercial Cu-based catalysts. The effects of various operation conditions, such as temperature, pressure, contact time (W/F), and H2/COx and CO/COx ratios, on the methanol yield were investigated. The Cu-based catalysts containing a small amount of Mg showed a higher a Read More

Stress corrosion cracking (SCC) is one of major threats against the integrity of the structural materials composing a nuclear power plant (NPP). Lead is deleterious element accelerating the SCC of Alloy 600 used as a steam generator tubing material in an NPP. In the present work, the oxide property grown on an Alloy 600 surface was evaluated as a function of PbO content using electrochemical impedance spectroscopy (EIS Read More

A new fabrication process for generating open-cell metallic and alloyed foams was developed by combining electrical explosion of wire (EEW) and electrospray (ESP) techniques. Fe-Cr-Al alloy nano-powders prepared by EEW in ethanol were used as a starting material, and commercial polyurethane (PU) sponges were used as templates. Fe-Cr-Al foams were successfully fabricated with porosities greater than 90%. The p Read More

In Pressurized Water Reactor (PWR) power plants, Alloy 600, a Ni-Cr-Fe alloy, is used for steam generator tube materials. However, these tubes have experienced a lot of corrosion problems during their operation times. Several chemicals have been investigated for inhibitors of stress corrosion cracking (SCC) in the tube materials. Titanium dioxide (TiO2), which is sonochemically treated in water, was tested to evaluate Read More

ODS steel normally contains an exceptionally high oxygen concentration owing to oxygen adsorption on the metal powder surfaces, as well as to the contamination during mechanical alloying and consolidation. In this study, the effect of oxygen concentration on the size distribution of oxide particles in ODS steel has been investigated. The oxygen concentration in one ODS steel sample was about 7000 ppm (sample A), while Read More

Ti3Al0.3Si0.7C2 compounds were synthesized via the powder metallurgical process, and oxidized isothermally and cyclically between 900 and 1200 °C in air. They had good thermal shock resistance, forming adherent oxide scales during cyclic oxidation. They oxidized to rutile-TiO2, α-Al2O3, and amorphous SiO2, together with gaseous escape of carbon. The oxide scales that formed during isothermal and cyclical oxidation were si Read More

The formation of hollow Cu oxide nanoparticles through the oxidation process has been studied with Cu nanoparticles produced by the plasma arc discharge method. The initial copper nanoparticles had a size range of 40 - 60 nm and a thin Cu2O layer on the surface. After oxidation at 100°C, there was no significant change in the particles. After oxidation at 200°C, however, the particles consisted of Cu2O and CuO instead of Read More

Waste PCBs (Printed Circuit Boards) from LCDs (Liquid Crystal Displays) contain valuable raw materials, Sn, Cu, and other noble metals. Among these, high purity tin was obtained by electro-winning after appropriate acid leaching of tin. For this, leaching and electro-winning process parameters were optimized for solution stability, dissolution and electrolytic efficiency. Two aqueous procedures were developed and tes Read More

The effects of aluminum and strontium content on an Mg-Al-Ca-Sr alloy were investigated in terms of microstructural and mechanical properties. The addition of up to 2 wt% of strontium to the Mg-5Al-2Ca alloy caused the major interdendritic intermetallic phase to change from Al2Ca to a combination of Mg2Ca, Al4Sr, and Mg17Sr2. Moreover, the addition of 2 wt% of aluminum to the Mg- 5Al-2Ca-xSr alloys caused the for Read More

Refining silicon and silicon nanoparticles are an important research area in solar energy research. These are related with solar cell efficiency. Silicon nanoparticles are also used for thin film solar cell and screen printing technology. We review the synthesis of silicon nanoparticles and refining of silicon. Refined silicon nanoparticles with minimal boron content were fabricated with transferred arc plasma equipped with i Read More

Nanocrystalline n-type 95%Bi2Te3-5%Bi2Se3 bulk with prepared by the combined application of high energy milling and hot extrusion processes in this study. The effect of milling time on the microstructure of powders was characterized by scanning electron microscopy (SEM). With increasing milling time, powder size quickly decreased, and finally yielded nanocrystalline Bi2Te3 of less than 200nm grain size and of spherical mo Read More

In this work, we implemented a chemical rate theory model for the growth of nano-sized point defect clusters (PDCs) and copper- rich precipitates (CRPs) which can change the mechanical properties in the reactor pressure vessel material of a nuclear power plant. For the calculation of irradiation defect evolution, a number of time-dependent differential equations were established and numerically integrated. The conce Read More

The effects of Nd-Fe-B magnet scrap size on extraction behavior were investigated by liquid metal extraction using molten Mg. The magnet scraps with Mg were placed into a stainless steel crucible and then heated to 1,073K for 10 to 50min. The amount of extracted Nd after liquid metal extraction process was increased with an increasing with holding time and scrap size, and the maximum contents of Nd in Mg were obse Read More

The niobium capacitor shows somewhat more unstable characteristics than the commercial tantalum capacitors, but it will be nonetheless considered as an excellent substitute of tantalum capacitors in the future. In this study, niobium powder is fabricated by metallothermic reduction process using K2NbF7 as a raw material, KCl and KF as diluents, and Na as a reducing agent. The niobium particle size greatly decrease Read More

The CVD apparatus for the uniform coating of silicon carbide was suggested and realized into a 3-dimensional computer-aided design (CAD) model. An experimental condition is simulated with a computational fluid dynamic program to obtain temperature and flow distribution in the CVD chamber. The simulated temperature showed the very uniform distribution especially in the hot zone region and that is thought to be th Read More

The effective recovering process that consists of air-jetting, centrifugation and air-classifying was developed for phosphor recycling from flat panel display devices. At the first processing stage of air-jetting, 95% phosphor could be recovered while the recovery rate was dependent on the dimension of CCFLs. After two subsequent stages of mechanical separation, Blue, Red and Green rich phosphor could be selectively colle Read More

We have developed a mass production process of Si quantum dots using photo-induced chemical etching method with oxidation and etching agents and have investigated its optical properties. Average size of the fabricated Si quantum dots was estimated to be 2 nm. Absorption peaks of the fabricated quantum dots were observed in the short wavelength regions, e.g., 200 - 350 nm. On the other hand, in the case of raw sludg Read More

In this study, the effect of Sc addition on the microstructure and mechanical properties of Al-20Si alloys fabricated by extrusion of powders was investigated. The Al-Si-(Sc) powders produced by high pressure gas atomization were used in starting materials. The microstructure and structural characterization were performed by optical microscopy (OM), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and trans Read More

The purpose of this study is to investigate the microstructure and mechanical properties in 9Cr-1Mo-V steel and its weld. A 220 mm thick forged plate with a typical composition of G91based on ASME A336 was used. Narrow gap welds were produced by submerged arc welding (SAW) with two different welding speeds. The microstructures in the base metal were typical tempered martensite at all locations, and the sizes of prior Read More

The present work investigated the effects of MgO as a thermodynamic stabilizer and ZrO2 and mullite (3Al2O3·SiO2) as kinetic stabilizers on the mechanical properties of Al2TiO5 at high temperatures. Al2TiO5 was synthesized using reaction sintering at 1500, 1550, and 1600°C for 2 h. The mix-stabilized Al2TiO5 sintered at 1500°C showed the highest mechanical strength (138 MPa) at 1100°C, while the mullite-only Al2TiO5 s Read More

TaNx(1, 3 & 5 nm) films deposited on the Ag(10 nm)/Si(3 nm)/glass show dense microstructure, and this structure was stable even after annealing at 300 °C in Ar (80%) + O2 (20%) ambient for 5 min. The RMS (Root Mean Square) roughness of the films decreased with increasing the TaNx film thickness. The partial oxidation of TaNx was observed in TaNx(3 & 5 nm)/Ag(10 nm)/Si(3 nm)/glass at 300 °C annealing temperature, but Read More

The microstructures and electrochemical properties of rapidly-solidified silicon alloys mixed with various forms of carbon have been investigated. Rapidly-solidified Si70Ni15Ti15 (at%) alloy (SNT1515) ribbons were prepared by arc-melting, followed by melt spinning process in vacuum. The obtained ribbons were fragmented by ball milling to produce a fine powder of -500mesh. The alloy powder was mixed with various types Read More

Ultrasonic spray pyrolysis (USP) and thermal reaction were combined to fabricate lithium iron borate compound nanopowder in cost-effective and high throughput manner. This procedure exploits USP process to prepare homogenous precursor nanopowders, thereby imparting improved reaction during post thermal process. It is believed to be a distinguished route to produce a cathode material in lithium secondary battery.