Intrinsic Kinetics of Chlorination of WO<Subscript>3</Subscript> Particles With Cl<Subscript>2</Subscript> Gas Between 973 K and 1223 K (700 °C and 950 °C)

Chlorination is one of the methods applied in extractive metallurgy for the treatment of minerals to obtain valuable metals, such as titanium and zirconium. The possibility of applying chlorination metallurgy to other metals such as tungsten was the major aim of this study. The kinetics of the chlorination of tungsten oxide (WO₃) particles has been investigated by thermogravimetry between 973 K and 1223 K (700 °C and 950 °C) and for partial pressures of chlorine ranging from 15 to 70 kPa. The starting temperature for the reaction of WO₃ with chlorine is determined to be about 920 K (647 °C). The influence of chlorine diffusion through the bulk gas phase and through the particle interstices in the overall rate was analyzed. In the absence of these two mass-transfer steps, a reaction order of 0.5 with respect to chlorine partial pressure, and an activation energy of 183 kJ/mol were determined. For tungsten oxide particles of less than 50-μm size, a complete rate expression has been obtained.     

Effects of Reducing Gas on Swelling and Iron Whisker Formation during the Reduction of Iron Oxide Compact

The effects of different types of reducing gas on swelling and iron whisker formation during the reduction of iron oxide compacts were investigated. The compacts sintered in air at 1273 K were reduced at 1173 K in different reducing atmospheres. The results indicated that catastrophic swelling can happen in CO but not when H₂ is present in the reducing gas mixture. Scanning electron microscope (SEM) micrographs showed that catastrophic swelling was caused by a large amount of long iron whiskers formed during the reduction. The presence of N₂ and CO₂ in CO changed the amount of long iron whiskers and its distribution, which determined the extent of swelling.     

Disparities in exploitative and exploratory patenting performance across regions: Focusing on the roles of agglomeration externalities

We try to identify the determinants of regional variation in both exploitative and exploratory innovative competencies. Hereby, we focus on how a knowledge-creation mechanism with specialized externalities differs from one with diversified externalities. Innovative competence in the US is measured by local patenting performance; exploitative and exploratory patenting performances are distinguished by the degree of backward citation. Based on the extended knowledge-production function, including the two agglomeration externalities, our findings show that specialized externalities are associated with exploitation, while diversified externalities are positively related with both exploration and exploitation, regardless of industrial sectors.     

Unsupervised and non-parametric learning-based anomaly detection system using vibration sensor data

Multimedia Tools and Applications - In this paper, we propose an anomaly detection system of machines using a hybrid learning mechanism that combines two kinds of machine learning approaches,...     

Effect of Compositional Variation in TiO<Subscript>2</Subscript>-Based Flux-Cored Arc Welding Fluxes on the Thermo-physical Properties and Mechanical Behavior of a Weld Zone

The effect of compositional variation in TiO₂-based flux-cored arc welding fluxes on viscosity, wettability, and electronegativity was studied. The thermo-physical properties of the retrieved fluxes and their relationship with the mechanical properties of the weld zone, including tensile strength and micro-Vickers hardness, after welding were identified. Microstructural observation under similar welding conditions revealed significant grain coarsening at a corrected optical basicity (Λ^corr) of 0.62, resulting in reduced strength and hardness due to greater heat transfer. Welding fluxes containing TiO₂-based simple structural units should result in greater heat transfer due to the deficiency in complex [AlO₄]^5?- and [SiO₄]^4?-based structural units, as identified through spectroscopic analyses using fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The electronegativity of the retrieved fluxes was also evaluated since higher electronegativity results in greater absorption of electrons in the arc, resulting in arc condensation towards the center direction. Consequently, deeper penetration could be obtained, where the highest electronegativity was identified to be approximately 0.62 of the corrected optical basicity. Thus, both the thermal conductivity and electronegativity of the welding fluxes were identified to determine the heat transfer phenomenon during flux-cored arc welding.     

Structural evaluation of thermal stratification for PWR surge line

Recent observations at operating plants and subsequent US NRC requirements have identified flow stratification in surge lines as a phenomenon that must be considered in the design basis of surge lines. To address these concerns, the stratified loading conditions were included in the design of YGN 3 and 4 surge line as a design basis transient and pipe temperature and displacement measurement were taken during YGN 3 pre-core hot functional testing to determine the degree of surge line flow stratification. The measured displacements and temperatures were extensively reviewed and evaluated in detail: (1) to verify the validity of the thermal hydraulic model used to predict the pipe top-to-bottom temperature differentials; (2) to analytically correlate measured surge line temperatures and displacements; and (3) to confirm the validity of the stratified flow analysis procedure. This paper shows that the stratified flow phenomenon is generic and therefore generic loadings can be developed and evaluated for the surge line analyses.     

Ultrastrong Medium‐Entropy Single‐Phase Alloys Designed via Severe Lattice Distortion

Severe lattice distortion is a core effect in the design of multiprincipal element alloys with the aim to enhance yield strength, a key indicator in structural engineering. Yet, the yield strength values of medium‐ and high‐entropy alloys investigated so far do not substantially exceed those of conventional alloys owing to the insufficient utilization of lattice distortion. Here it is shown that a simple VCoNi equiatomic medium‐entropy alloy exhibits a near 1 GPa yield strength and good ductility, outperforming conventional solid‐solution alloys. It is demonstrated that a wide fluctuation of the atomic bond distances in such alloys, i.e., severe lattice distortion, improves both yield stress and its sensitivity to grain size. In addition, the dislocation‐mediated plasticity effectively enhances the strength–ductility relationship by generating nanosized dislocation substructures due to massive pinning. The results demonstrate that severe lattice distortion is a key property for identifying extra‐strong materials for structural engineering applications.     

Dry sol-gel polycondensation of hydrosilanes to organosilicas catalyzed by colloidal nickel nanoparticles

The dry sol-gel polycondensation at toluene in ambient air atmosphere of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) to silica p-X-C6H4SiO15 in high yield, catalyzed by colloidal nickel nanoparticles in-situ generated from nickelocene(II), nickel(II) acetate, and bis(1,5-cyclooctadiene)nickel(0), is described. Similar catalytic activities were observed for the catalysts. Similarly, the dry sol-gel polyco-condensation p-X-C6H4SiH3 (X = CH3, CH3O, F, Cl):C6H4SiH3 (9:1 mole ratio) at toluene in ambient air atmosphere of was performed to yield co-silicas (p-X-C6H4SiO1.5)9(p-X-C6H4SiO1.5)1 in high yield using nickelocene. The co-gels with higher molecular weights and TGA residue yield were obtained when compared to the homogels. The highest yield, molecular weight, polydispersity index, and TGA residue yield were obtained for p-Cl-C6H4SiH3. Some degree of unreacted Si-H bonds still remained in the gel matrix because of steric bulkiness. All the insoluble gels adopt an amorphous structure with a smooth surface. A plausible mechanism for the dry sol-gel reaction was suggested.