Hardenability Improvement Mechanisms and Hardenability-Controlling Factors in Steels With Combined Mo–B Addition

Metallurgical and Materials Transactions A - To elucidate the hardenability improvement mechanisms and hardenability-controlling factors in low-carbon (C) steels with the combined addition of...     

An etching characterization method for revealing the plastic deformation zone in a SUS303 stainless steel

Etching characteristics used to reveal localized plastic deformation zones in a SUS303 stainless steel have been examined. The etching was conducted on a sample using an etchant consisting of 5-g ferric chloride, 50-mL hydrochloric acid, and 100-mL water. The sample was deformed severely and heated to various temperatures before the etching process. With this etching technique, the plastically deformed area is clearly observed even at low magnification. This is due to a change of the microstructural characteristics in the plastic deformation zone. There are different microstructure patterns that reveal the plastic zone in the sample with and without heating, e.g., plastic zone in the sample with heating to 800 °C is observed clearly due to randomly oriented crystals and recrystallized small grains with precipitated nano-size particles. Details of the etching characteristics that reveal the plastic deformation zone are further discussed.     

Preparation of ultrasmooth and defect-free 4H-SiC(0001) surfaces by elastic emission machining

In this work, elastic emission machining (EEM), which is a precise surface-preparation technique using chemical reactions between the surfaces of work and fine powder particles, is applied to the flattening 4H-SiC (0001) surface. Prepared surfaces are observed and characterized by optical interferometry, atomic force microscopy (AFM), and low-energy electron diffraction (LEED). The obtained images show that the processed surface has atomic-level flatness, and the subsurface damage and surface scratches of the preprocessed surface are almost entirely removed.     

Physically Asymmetric Star Network with CWDM Wavelength Router

We propose and demonstrate a CWDM full-mesh wavelength-routing system with an asymmetric physical star topology. We design a wavelength router to optimize this topology in which the node distances from the wavelength router are unequal. In addition, the router utilizes all the wavelengths making it possible to increase the maximum number of nodes in the system. The routing function is confirmed experimentally using transceivers with two different optical budgets     

Demand–Supply Balancing Capability Analysis for a Future Power System

Under the anticipated high penetration of variable renewable energy generation such as photovoltaics and higher share of nuclear generation, the issue of supply–demand balancing capability should be evaluated and fixed in a future power system. Improvement of existing balancing measures and new technologies such as demand activation and energy storage are expected to solve the issue. In this situation, a long‐range power system supply–demand analysis should have the capability to evaluate the balancing capability and balancing countermeasures. This paper presents a new analysis methodology of activated demand model and evaluation of supply–demand balancing capability for a long‐range power system demand–supply analysis model, ESPRIT. Model analysis was made to verify the new methodology of the tool including day‐ahead scheduling of a heat pump water heater, an EV/PHEV, and a battery. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 21–30, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22488     

Structural, Mechanical and Erosion Properties of Yttrium Oxide Coatings by Axial Suspension Plasma Spraying for Electronics Applications

Yttrium oxide (Y₂O₃) coatings have been prepared by axial suspension plasma spraying with fine powders. It is clarified that the coatings have high hardness, low porosity, high erosion resistance against CF₄ -containing plasma and retention of smooth eroded surface. This suggests that the axial suspension plasma spraying of Y₂O₃ is applicable to fabricating equipment for electronic devices, such as dry etching. Surface morphologies of the slurry coatings with splats are similar to conventional plasma-sprayed Y₂O₃ coatings, identified from microstructural analysis. Dense coating structures with no lamellar boundaries have been seen, which is apparently different from the conventional coatings. It has also been found that crystal structure of the suspension coatings mainly composed of metastable monoclinic phase, whereas the powders and the conventional plasma spray coatings have stable cubic phase. Mechanism of coating formation by plasma spraying with fine powder slurries is discussed based on the results.     

Charge evaluation of EDLC for autonomous microgrid energy storage

Electric double layer capacitor (EDLC) is now playing more and more roles in microgrids for renewable energy storage due to its characteristic merits in high charging and high energy density. Different charging modes of EDLC are mainly studied in this paper. Compared with traditional constant-voltage and constant-current charging modes, constant-power charging mode (CPCM) ranks more reasonable positions for autonomous systems. Numerical calculations were presented for practical analysis, which was validated to be accurate enough and applicable by a simple case with PV/EDLC system configuration. Charging efficiency of different charging modes was also reviewed with strict mathematic deductions. Furthermore, trade-off problems, between charging time/efficiency/energy loss, were also investigated in brief for practical optimization of application occasions. For practical applications, how to utilize and manage the relationship of shifting modes in a reasonable way can be dealt with the actual requirements.     

Visualization of deuterium flux and grain boundary diffusion in duplex stainless steel and Fe–30 % Ni alloy,using secondary ion mass spectrometry equipped with a Ga focused ion beam

Time of flight secondary ion mass spectrometry (TOF-SIMS) equipped with a high spatial resolution Ga focused ion beam (Ga-FIB) was applied to understand hydrogen diffusion and desorption behavior in duplex stainless steel and Fe–30 % Ni alloys. Deuterium was used as a tracer of hydrogen. Results showed that the secondary ion intensity from body-centered cubic (bcc) and face-centered cubic (fcc) Fe represents the flux of deuterium from the surface and the concentration of deuterium, respectively. The deuterium-depleted zone can be visualized from the interface between bcc and fcc phase to fcc Fe on the surface. Furthermore, direct visualization of the grain boundary diffusion of deuterium is also possible in fcc Fe–30 % Ni alloys, using Ga-FIB-TOF-SIMS.