Eiji Yamasue

Thermal conductivities of silicon and germanium in solid and liquid states measured by non-stationary hot wire method with silica coated probe

The thermal conductivities of silicon and germanium have been determined using the non-stationary hot wire method. Measurements were carried out over the temperature range 293–1724 K on solid and liquid silicon and on liquid germanium in alumina tube. For solid silicon, the thermal conductivities were about 139 W/mK at 293 K and 19 W/mK at 1573 K and displayed temperature dependence steeper than T � 1 ; where T is the temperature. Calculation of thermal conductivities for solid silicon based upon isotope, three-phonon and four-phonon scatterings indicates that phonon conduction dominates heat conduction at temperatures below 1000 K. At temperatures above 1000 K, on the contrary, contributions from electron, hole and electron–hole pair to heat conduction became greater progressively with a temperature rise. For liquid silicon, the thermal conductivity was about 57 W/mK at 1700 K and exhibited a slight increase with an increase in temperature. The thermal conductivity of liquid germanium was about 43 W/mK at 1273 K and slightly increased with increasing temperature. In both liquids, temperature dependency of thermal conductivity values was discussed from the view point of the Wiedemann–Franz law. r 2002 Elsevier Science B.V. All rights reserved.

Deviation from Wiedemann–Franz Law for the Thermal Conductivity of Liquid Tin and Lead at Elevated Temperature

The thermal conductivities of tin and lead in solid and liquid states have been determined using a nonstationary hot wire method. Measurements on tin and lead were carried out over temperature ranges of 293 to 1473 K and 293 to 1373 K, respectively. The thermal conductivity of solid tin is 63.9±1.3 W⋅m−1⋅K−1 at 293 K and decreases with an increase in temperature, with a value of 56.6±0.9 W⋅m−1⋅K−1 at 473 K. For solid lead, the thermal conductivity is 36.1±0.6 W⋅m−1⋅K−1 at 293 K, decreases with an increase in temperature, and has a value of 29.1±1.1 W⋅m−1⋅K−1 at 573 K. The temperature dependences for solid tin and lead are in good agreement with those estimated from the Wiedemann–Franz law using electrical conductivity values. The thermal conductivities of liquid tin displayed a value of 25.7±1.0 W⋅m−1⋅K−1 at 573 K, and then increased, showing a maximum value of about 30.1 W⋅m−1⋅K−1 at 673 K. Subsequently, the thermal conductivities gradually decreased with increasing temperature and the thermal conductivity was 10.1±1.0 W⋅m−1⋅K−1 at 1473 K. In the case of liquid lead, the same tendency, as was the case of tin, was observed. The thermal conductivities of liquid lead displayed a value of 15.4±1.2 W⋅m−1⋅K−1 at 673 K, with a maximum value of about 15.6 W⋅m−1⋅K−1 at 773 K and a minimum value of about 11.4±0.6 W⋅m−1⋅K−1 at 1373 K. The temperature dependence of thermal conductivity values in both liquids is discussed from the viewpoint of the Wiedemann–Franz law. The thermal conductivities for Group 14 elements at each temperature were compared.

Hybrid LCA of a Design for Disassembly Technology: Active Disassembling Fasteners of Hydrogen Storage Alloys for Home Appliances

In the current recycling system of end-of-life (EoL) appliances, which is based on shredding, alloying elements tend to end up in the scrap of base metals. The uncontrolled mixing of alloying elements contaminates secondary metals and calls for dilution with primary metals. Active disassembling fastener (ADF) is a design for disassembly (DfD) technology that is expected to solve this problem by significantly reducing the extent of mixing. This paper deals with a life cycle assessment (LCA) based on the waste input-output (WIO) model of an ADF developed using hydrogen storage alloys. Special attention is paid to the issue of dilution of mixed iron scrap using pig iron in an electric arc furnace (EAF). The results for Japanese electrical and electronic appliances indicate superiority of the recycling system based on the ADF over the current system in terms of reduced emissions of CO(2). The superiority of ADF was found to increase with an increase in the requirement for dilution of scrap.

Performance Analysis Between Well-Being, Energy and Environmental Indicators Using Data Envelopment Analysis

Data Envelopment Analysis (DEA) has been applied to know the performance of 40 countries in terms of energy, environmental and well-being related indicators. The method used is a basic Charnes, Cooper and Rhodes (CCR) DEA model applied to countries treated as Decision Making Units (DMUs) with two energy related indicators as inputs and one well-being indicator as output. The variables were selected based on correlations between seven energy-environmental indicators, and eight well-being indexes. From the correlations, two DEA models were constructed and compared. The first one, named “Production” DEA model, using electricity consumption per capita and CO2 emissions per capita as inputs and GDP per capita as output. The second one, “Development” DEA model using the same inputs but Human Development Index (HDI) as output. Results show that most developed countries compared to the others have low efficiency in the production model and even lower results in the development one. Among the “best” performing countries were Costa Rica, Ghana and the Philippines for the production model, and Tanzania and Nigeria for the development one.

Formation of metastable phases by high-energy ball milling in the Ti-O system

Investigation of the phase formation during mechanical alloying (MA) was systematically performed in the Ti-O system. Powder mixtures of Ti and TiO2 with various compositions and single-phase Ti2O, α-TiO and α-Ti2O3 powders were respectively subjected to planetary ball milling. According to X-ray diffractometry, high-temperature phases such as α-Ti solid solution, β-TiO and γ-Ti2O3 were observed for Ti-33 at%O (after 4 h of MA), 40–55 at%O (8 h) and 60 at%O (4 h), respectively. The metastable phase formations are discussed from various viewpoints including local pressure, local temperature, point defects, impurity and repeated deformation. The phase formations by MA are explained by primitive unit cell volume of the crystal structure as an indicator.

Innovations in steelmaking technology and hidden phosphorus flows

This article will outline the historical transition in the flow of phosphorus in steelmaking technology, and examine the current and future phosphorus flow in steel production and the peripheral steelmaking processes. History provides many instances of innovative changes in steelmaking processes driven by various issues associated with raw materials which emerged over time, such as supply, quality and cost issues. The major steel countries with a long history, including Sweden and Japan, have shown flexibility in their ability to adapt to the changes in the value of resources and geopolitical conditions over times, and have enacted survival resource utilization measures over many centuries, leading to improvements in their respective steelmaking processes. Considering these success stories, it stands to reason that the ideal state of steelmaking is one with a clear stance with regard to resource policy.

Adhesion Properties of Milled CuO-CeO2/γ-Al2O3 on Metallic Substrate for Automotive Catalytic Converter

Adhesion properties of CuO-CeO2/γ-Al2O3 layers on FeCrAl metallic substrate was investigated, where the hybrid preparation method between suspension and sol-gel is further combined with the mechanical milling process of the slurry. Poor coating adhesion was observed when the slurry is vigorously stirred, where the milled powders are agglomerated, and the stirring process hardly reduces the particle size. The combined method was found to significantly improve the adhesion property between the milled CuO-CeO2 catalytic layer and the γ-Al2O3 washcoat, compared with the vigorous stirring of the slurry. The so-called “over-milling” phenomenon was also exhibited, where the elongated large particles are observed after sintering of the longer-milled powders, leading to the lowered adhesion quality.

Analysis of Intentions to Recycle Electronic Waste (E-Waste) Using the Theory of Planned Behavior: A Case Study in Urban Areas of Vietnam

The theory of planned behavior (TPB) was used as a theoretical framework for systematically investigating the determinants of e-waste recycling behavior. The data for this study were collected from 1,806 households living in Hanoi city, Danang city and Hochiminh city, Vietnam. The findings suggest that TPB components explained a substantial proportion of variance in intentions to recycle e-waste (26.7%). The most important predictor was perceived behavioral control (β = 0.331, p < 0.001), the second strongest predictor was subjective norm (β = 0.159, p < 0.001) and the weakest was attitudes (β = 0.108, p < 0.001). Recycling habit and interest in economic benefit also were found to be significantly contributed to e-waste recycling intentions. Implication of the findings for establishing a management and recycling system specified for e-waste in Vietnam was discussed.

Molecular dynamics study of the milling-induced allotropic transformation in cobalt

The milling-induced allotropic transformation in cobalt from the stable hcp phase into the fcc phase has been studied by molecular dynamics simulation. Uniaxial compression of nano-sized spheres composed of the hcp Co phase is simulated as the elementary process of milling. The c axis is tilted from the compression direction at 0°, 30°, 60° and 90° to investigate the orientation dependency. The Honeycutt–Andersen index analysis and powder X-ray diffraction pattern calculation by the Debye formula show that the transformation into the fcc phase occurs when the tilt angle is 0–60°. The basal slip is essential for the transformation when the tilt angle is 60°, while the c axis compression-induced transformation mode is observed for the 0° tilt angle, which involves lattice contraction along the c axis and lattice dilation in the basal plane. Both modes are observed for the 30° tilt angle. Analysis of the pressure induced during compression reveals that the pressure necessary to initiate the latter transformation mode is too high to attain during conventional ball milling. The basal slip mode is proposed as the probable transformation mode for the milling-induced allotropic transformation in Co.

Magnetic field effects on photodecomposition of methylene blue over ZnO particles

The magnetic field effects (MFEs) on the photocatalytic degradation of methylene blue (MB) solution over ZnO particles have been studied. A positive MFE was clearly confirmed, while the MFE is decreased with increasing the interval time (settling time) between the preparation of MB solution and the start of photodegradation. It is suggested that one of the key factors of the MFEs is the amount of dissolved oxygen in the MB solution.