Boron Particle Composite Plating with Ni-B Alloy Matrix

Ni–B alloy films containing amorphous boron particles (referred to as “Ni–B alloy composite films”) were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their hardness was evaluated. The content of boron particles in the alloy composite films increased with boron particle concentration in the plating baths. In addition, the total boron content in the films increased with decreasing current density, reaching a maximum value of 34.3 atom %. The boron particles were homogeneously distributed in these alloy composite films and exhibited no cohesion. Heat-treatment of the alloy composite films consisting of a Ni–B alloy matrix and the boron particles led to a phase conversion from an inhomogeneous amorphous phase to stable homogeneous crystalline phases, which were similar to those in the Ni–B binary alloy phase diagram. The hardness of the Ni–B alloy 34.3 atom % B composite film was higher than that of a Ni–B alloy film both before and after heat-treatment.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY. 157(2):D119-D125 (2010)journal articl

Phosphorus Particle Composite Plating with Ni-P Alloy Matrix

Ni-P alloy films containing phosphorus particles (called Ni-P alloy composite films) were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their friction properties were evaluated using a ball-on-plate method. Composite electroplating in the nickel sulfate and chloride bath containing phosphorus acid and micrometer-sized phosphorus particles resulted in the Ni-P alloy coating with enhanced deposit phosphorus content. The phosphorus content of the films increased with increasing phosphorus particle concentration in the composite plating baths, reaching a maximum value of 29.0 atom %. The phosphorus particles were homogeneously distributed in this Ni- 29.0 atom % P alloy composite film. Heat-treatment converted the phases of the alloy composite films from an amorphous phase to stable crystalline phases, which are the same as those in the Ni- P binary alloy phase diagram. The friction coefficients of the Ni- P alloy films increased with increasing cycle number, whereas those of the Ni- P alloy composite films remained relatively constant. The alloy composite films had lower friction coefficients than the Ni- P alloy films both before and after heat-treatment. These results indicate that phosphorus particles are beneficial for maintaining a lower and stable friction coefficient during the ball-on-plate reciprocating friction test.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY 156: D283-D286(2009)journal articl

THE CHARACTERISTICS OF BACKWARD WALKING AND BACKWARD RUNNING IN PRIMARY SCHOOL CHILDREN

The purpose of this study is to identify the characteristics of both backward walking (BW) and backward running (BR) and show the differences between two kinds of movements according to age. One 'hundred and four primary school children and varsity 20 students participated in this study. The SUbjects were divided into four groups. 15-meters-long lane was used in this experiment. All video pictures were manually digitized on Sony Motion Analyzer (SMC-70G). Cycles of motion in BW &BR were analyzed. The walking velocity didn't increase so with age in BW-test, but the results of BR-test revealed that running velocity increased with age. Step length was increased with age in each test. Step frequency of BR didn't increase with age. Step frequency in BW didn't increase with age. We categorized the form using examples from Miyamaru's procedure. BW was categorized to 5 patterns, and BR divided to 6 patterns

A Numerical Simulation of Evolution Processes and Entropy Generation for Optimal Architecture of an Electrochemical Reaction-Diffusion System: Comparison of Two Optimization Strategies

Employment of electrochemical energy devices is being expanded as the world is shifting toward more sustainable power resources. To meet the required cost efficiency standards for commercialization, there is a need for optimal design of the electrodes. In this study, a topology optimization method is proposed to increase the performance of an electrochemical reaction-diffusion system. A dimensionless model is developed to characterize the transport and rate processes in the system. Two optimization strategies are introduced to improve system performance using a heterogeneous distribution of constituents. In addition, an entropy generation model is proposed to evaluate the system irreversibilities quantitatively. The findings show that the system performance could be enhanced up to 116.7% with an optimal tree-root-like structure. Such a heterogeneous material distribution provides a balance among various competing transport and rate processes. The proposed methodology could be employed in optimal design of electrodes for various electrochemical devices. This study also offers a fundamental comprehension of optimal designs by showing the connection between the optimal designs and the entropy generation. It is revealed that a less dissipating system corresponds to a more uniform current and entropy generation. Some recommendations are also made in choosing a proper optimization approach for electrochemical systems.Alizadeh M., Charoen-amornkitt P., Suzuki T., et al. A Numerical Simulation of Evolution Processes and Entropy Generation for Optimal Architecture of an Electrochemical Reaction-Diffusion System: Comparison of Two Optimization Strategies. Journal of The Electrochemical Society 170, 114520 (2023); https://doi.org/10.1149/1945-7111/ad0a7c

Topological optimization for tailored designs of advection–diffusion-reaction porous reactors based on pore scale modeling and simulation: A PNM-NSGA framework

Alizadeh Mehrzad, Gostick Jeff, Suzuki Takahiro, et al. Topological optimization for tailored designs of advection–diffusion-reaction porous reactors based on pore scale modeling and simulation: A PNM-NSGA framework. Computers & Structures 301, 107452 (2024); https://doi.org/10.1016/j.compstruc.2024.107452

Effect of Rust Inhibitor in Brine on Corrosion Properties of Copper

In this study, the effects of rust inhibitors in brine on corrosion behaviors of copper were investigated by measurement of cathode and anode polarization curves and an immersion test. For rust inhibitors, benzotriazole, sodium benzoate and sodium nitrite were prepared. From measurement results of cathode and anode polarization curves, it was found that the corrosion rate of copper in the benzotriazole solution is low and a stable passive film with excellent corrosion resistance generates on the surface of copper in the solution. In the case of the sodium benzoate solution, the corrosion resistance of the passive film was inferior to that in the benzotriazole solution although the passive film generated on the surface of copper. In contrast, the passive film scarcely generated on the surface of copper in the sodium nitrite solution. The result shows that the rust preventive effect of the solution to copper is weak. Furthermore, the immersion test revealed that the benzotriazole solution has the rust preventive effect to copper. In contrast, the effect of the sodium benzoate solution is weak and that of the sodium nitrite solution is scarcely expected

Mixed topology optimization: A self-guided boundary-independent approach for power sources

As the use of electrochemical devices becomes more prevalent, advanced optimization techniques, such as topology optimization, are being employed to improve their performance. Among various electrochemical systems, power sources have an intrinsic best operating point that corresponds to the maximum output power. This study proposes a mixed topology optimization approach to enhance the performance of these systems by a simultaneous modification of electrode structure and the working condition. In contrast to the conventional approaches, the proposed method focuses on enhancement of the maximum power point. Thanks to its self-guidance feature, this technique outperforms conventional topology optimization methods and eliminates the need for a prior decision on the optimization starting point. Therefore, the proposed approach has a significant potential for adapting the material distribution to the best working condition. The proposed approach enables more effective topological optimization and takes the utilization of topology optimization in power sources to the next level.Alizadeh M., Charoen-amornkitt P., Suzuki T., et al. Mixed topology optimization: A self-guided boundary-independent approach for power sources. Energy Conversion and Management 294, 117567 (2023); https://doi.org/10.1016/j.enconman.2023.117567