Helmut Takahiro Uchida

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Helmut Takahiro verified their affiliation via an institutional email.

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• Ph.D.
• Associate Professor (Full) at Tokai University

The hydrogenation of nanocrystalline Mg films on Si- and Pd substrates was studied by electromotive force and X-ray diffraction measurements. A strong loading current dependency of the hydrogenated volume was found. While for high current densities i > 1 × 10-6 A cm-2 only about 10 nm could be hydrogenated, about 200 nm could be reached for small c...

Electrochemical hydrogen permeation measurements and in situ gas-loading X-ray diffraction measurements were performed on polycrystalline Mg films. Hydrogen diffusion constants, the hydride volume content and the in-plane stress were determined for different values of driving forces at 300 K. For α-Mg–H, a hydrogen diffusion constant of D H Mg = 7...

2-layer laminated sheets (PE/PET) with Polyethylene (PE) and Polyethylene Terephthalate (PET) were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (≦1.30 MGy) homogeneous low energy electron beam irradiation (HLEBI) prior to hot-press under 5 MPa and 403 K. Although the weak hot-press adhesion of the PE/PE...

Magnetostrictive materials are widely used to build actuators, sensors, and vibration energy harvesting devices. Generally, the interfacial adhesion between the substrate and thin films plays important roll from the practical point of view. Therefore, establishing precise techniques to evaluate the interfacial adhesion energy are quite important as...

The thermodynamics of structural phase transformations in thin films depends on the mechanical stress that can be released by plastic deformation. For thin films below a critical film thickness, plastic deformation is energetically unfavourable: thus, the system stays coherent and stress remains. For PdHc films less than 22 nm thick, a new situatio...

Polycarbonate (PC) is a highly recyclable thermoplastic with high impact strength that bodes well to re-melting extrusion and shredding for positive environmental impact. For the goal of improving impact strength further, layered carbon fiber (CF) reinforcement has been added between PC sheets by hot pressing at 6.0 MPa and 537 K for 8 min. An addi...

The development of efficient hydrogen recovery methods for fusion reactor divertor materials is key to their long-term stability. In this work, a novel hydrogen recovery technique using solid-state diffusion was investigated, focusing on the intrinsic hydrogen solubility properties of metals.A tungsten (W) substrate was coated with a Niobium (Nb) t...

TiNi-based alloys are widely utilized in various engineering and medical applications. This study presents a newly developed and optimized technology for producing TiNi wires with a diameter of 40 μm utilizing a combined mechano-chemical treatment and drawing process. The resulting thin wires were tested and characterized using multiple methods to...

It is a serious problem that short carbon fiber reinforced polyamide 66 (SCFRPA66) cannot be easily shaped by 3D-printing for practical usages. In order to improve on the brittleness, homogeneous low potential electron beam irradiation (HLEBI) to both sides of 3D-SCFRPA66 samples was found to increase strain at tensile strength (εts), corresponding...

In short-carbon-fiber-reinforced polyamide 66 articles shaped by 3D printing (3D-SCFRPA66), the interfaces between printed layers are often susceptible to damage, and the composite is excessively brittle. Therefore, a novel treatment for 3D-printed short-carbon-fiber-reinforced polyamide (3D-SCFRPA66) using homogeneous low-potential electron beam i...

Understanding resonance phenomena in materials is crucial in many fields, from controlling noise in small mobile devices to designing seismic-safe large structures or in energy harvesting. Resonance depends on material elasticity and its shape, influenced by temperature. While controlling elastic properties can control vibrations, seeking practical...

Conventionally, vibration energy and sound energy are emitted as noise and vibration. We have proposed a system that converts the vibration of the plate into energy. In this study, a circular plate of constant thickness, on which a piezoelectric element was installed, was adopted as the host structure of an energy-harvesting system. The plate was s...

Since 1998, our target of the projects has been the international active collaborations for Research for constructed and smart materials with original concepts. Excellent achievements were getting PhD (INSA Lyon) of master (Tokai U.) M. Kanda as well as more than 30 papers worked with three Research Unites in France.

As part of the international effort to deal with climate change, the renewable energy sources needed by society will fluctuate over time and season. Meanwhile, there is a demand for a stable supply on the consumption side. Hydrogen is therefore attracting attention as a low environment load energy carrier to bridge the gap between them. A technical...

Carbon fiber reinforced thermoset (TS) plastics (CFRP) are widely used as structural materials. However, TS CFRP requires a long curing time, resulting in poor productivity. To reduce the production time for composite fabrication, the use of thermoplastic polycarbonate as a base material, which can be molded by hot pressing, has been considered. Th...

New types of hybrid aluminum joints: Al/acrylonitrile butadiene styrene (ABS) carbon fiber reinforced thermoplastic polymers (CFRTP) designated Al/Ni-CFP/ABS, and Al/Stainless steel (18-8), (Al/Ni-CFP/18-8), by Ni-plated carbon fiber plug (Ni-CFP) insert not before seen in the literature have been fabricated. The goal is to take advantage of extrem...

In an interlayered carbon fiber-reinforced polycarbonate polymer (CFRPC) composite composed of three sized of CF plies, alternating between four PC sheets, designated [PC]4[CF]3, and a new process of activating CF cross-weave cloth plies directly on both sides with homogeneous low-energy electron beam irradiation (HLEBI) before lamination assembly...

A literature review of up-to-date methods to strengthen Ti/carbon-fiber-reinforced polymer (CFRP) hybrid joints is given. However, there are little or no studies on Ti/CFRP joints by carbon fiber plug insert, which takes advantage of the extremely high surface adhesion area of ~6 μm CFs. Therefore, we cover the current status and review our previou...

New types of hybrid aluminum joints: Al-acrylonitrile butadiene styrene (ABS) carbon fiber reinforced thermoplastic polymer (CFRTP) designated Al/Ni-CFP/ABS, and Al-18-8 Stainless steel, Al/Ni-CFP/18-8, by Ni-plated carbon fiber plug (Ni-CFP) insert not before seen in the literature have been fabricated. The goal is to take advantage of extremely h...

Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (Vc) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, h...

As the hydrogen society progresses, Fuel Cell Vehicles (FCVs) are rapidly becoming more widespread. Metal hydrogen permeable membranes, which are the essential parts of the hydrogen fuels for polymer electrolyte fuel cells (PEFCs), require an alternative material to palladium from a cost point of view. Austenitic stainless steel, which is low cost,...

Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (Vc) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, h...

Impact by hailstone, volcanic rock, bird strike, or also dropping tools can cause damage to aircraft materials. For maximum safety, the goal is to increase Charpy impact strength (auc) of a carbon-fiber-reinforced thermoplastic polyphenylene sulfide polymer (CFRTP-PPS) composite for potential application to commercial aircraft parts. The layup was...

Carbon fiber reinforced epoxy plastics (CFRP) is widely utilized for light weighted aerospace structural materials. However, CFRP require a long curing time of epoxy plastics to make composites. To shorten the molding time, the thermoplastics of polycarbonate instead of epoxy resin was applied to make composite of carbon fiber reinforced thermoplas...

Strong adhesion between recyclable thermoplastic (TP) polymer and carbon fiber (CF) has always been highly sought after. Therefore, for an interlayered CF reinforced TP polypropylene (CFRTPP) composite composed of 3 sized CF plies, alternating between 4 PP sheets, designated [PP]4[CF]3, a process of activating CF plies directly on both sides with h...

A literature review of up-to-date methods to strengthen Ti/carbon-fiber-reinforced polymer (CFRP) hybrid joints is given. However, there are little or no studies on Ti/CFRP joints by carbon fiber plug insert, which takes advantage of the extremely high surface adhesion area of ~6 μm CFs. Therefore, we cover the current status and review our previou...

This study examined the electricity generation performance of an energy-harvesting system, in which a circular plate with a piezoelectric element was excited by a harmonic point force. The theoretical electricity generation efficiency, which does not involve acoustic radiation from the plate, is greater than the experimental efficiency in such a po...

A new process of activating sizing film free (removed sizing) carbon fiber (SFF-CF) mats directly with electron beam irradiation (EBI) under oxygen-rich nitrogen gas prior to lamination assembly and hot-press was found to increase bending strength of CFRTP (CF reinforced thermoplastic polypropylene (PP)) interlayered composite composed of 3 SFF-CF...

Recently, the nuclear fusion power generation has attracted attention as a future power generation method. Tungsten is considered to be a promising candidate for divertor materials because of its excellent wear resistance, heat resistance, and low hydrogen gas solubility. However, the possibility of hydrogen embrittlement caused by hydrogen atoms d...

In this study, the in-plane stress in magnetostrictive thin films was evaluated by the changes in ion bombardment parameter Pi during the deposition. Despite the control of ion bombardment, the values of in-plane stress for the thin films were not continuous. This suggests that true stress of sputtered magnetostrictive thin films is governed by not...

The gyro effect is generally well known as a gyroscope sensor, but it is not very common to use it as an actuator. The gyro monorail is defined as a monorail that runs on a single rail using gyro effect. The largest advantage of the gyro monorail is that it runs on only a single rail and can run on different and existing tracks universally even at...

Negative magnetostrictive Sm-Fe films and Pd films were prepared by a DC magnetron sputtering process on single-crystal Si (100) substrates and on polyimide substrate. Controlled amount of hydrogen was loaded electrochemically via step-by-step method to the prepared films. The interferometric microscope and Newton ring method were applied to scan t...

The collisions of elastic bar and elastic beam have been analyzed. It is already known that the collision phenomena of a bar and a beam will change from only a one-time collision pattern to two or more intermittent types of collision patterns, and these patterns are determined by 1) the mass ratio m1/m2, 2) the natural-frequency ratio in the first-...

In recent years, many researchers have focused on the energy harvesting from the light, heat, vibration, etc., especially vibration energy harvesting has been reached for many applications. On the other hand, the acoustic energy is extremely smaller than the mechanical energy such as excitation energy. Thus, it has been discarded as noise except a...

In a layered carbon fiber reinforced thermoplastic polymer (CFRTP) composite composed of 3 cross-weave carbon fiber (CF) cloth sheets between 4 polypropylene (PP) mats, [PP]4[CF]3 (55 vol%-CFs), effects of: (1) factory provided sized CF (sizing film (SF) coated CFs with nano-scale rough surface after anodic oxidization), and (2) electron beam irrad...

A new method of linear connected joints (Ti/CF-plug/Epoxy) of Ti (Titanium) to Epoxy connected by CF-plug was innovated and developed, since fine carbon fibers (CFs) generate the extremely large friction force by their broad interface between metals and Epoxy polymer (M/Epoxy). Compared with glue and spontaneous adhesions of M/Glue/Epoxy and M/Epox...

A new process of internal activation of carbon fiber reinforced thermoplastic polymer (CFRTP) of polypropylene (PP) by applying electron beam irradiation (EBI) under oxygen (O2)–rich nitrogen gas (N2) atmosphere to CF chopped strand matt (CSM) layers prior to assembly and hot press to strengthen the typically weak CF/thermoplastic polymers (TPs) ad...

A new method to fabricate linear connected joints of Ti (titanium) to Epoxy polymer connected by CF-plug designated here as [Ti/CFW-CFRP] was innovated to enhance safety level of airplanes, since fine carbon fibers (CFs, 6-7/1000 mm) generate extremely large friction force by their broad interface between Ti and Epoxy [Ti/Epoxy] giving strong adhes...

Interconnection of Polymers to Ti by Using CF-Plug

Tensile strength at each accumulative probability of strength (Pf) was obtained for 28mass% carbon fibers (CF) reinforced thermoplastic polypropylene (PP) with and without sizing epoxy film on the fibers prior to making composites (CFRTP) of three cross CF cloth sheets and four PP matts, layer by layer. The sizing film covered on CF apparently impr...

Adhesion induced by homogeneous low voltage EB-irradiation (HLEBI) under O2 partial pressure from 0.02 mol% to 20 mol% in N2 gas atmosphere of CFRP/Al lamination has been successfully developed. Its adhesive tensile shear strength of CFRP/Al with 0.30 MGy-HLEBI under optimal O2 partial pressure in N2 atmospher of 0.2 mol% is 8.2 MPa, which is about...

An optimal condition to improve the adhesion of PTFE/PE lamination of Polytetrafluoroethylene (PTFE) untreated and Polyethylene (PE) activated by homogeneous low voltage electron beam irradiation (HLEBI) under each O2 partial pressure in N2 gas atmosphere prior to hot-press was studied. Its adhesive force of PTFE/PE with 0.22 MGy-HLEBI under optimal...

The authors regret that two important funding sources were unintentionally omitted from the final version of the manuscript. The complete acknowledgement should read: Funding by the Deutsche Forschungsgemeinschaft (DFG), projects PU 131/7-2, PU 131/9-1/2, SFB1073-C06, JO 348/6-2, and of the Czech Science Foundation, project P108/12/G043, is gratefu...

For thin metal films adhered to rigid substrates hydrogen uptake results in compressive stresses in the GPa range. Stresses affect the thermodynamics as well as the durability of thin films, but many films can release stress above critical stress values. Depending on the films' thickness, microstructure and adhesion to the substrate, which determin...

A Pd-H system is a model system suitable for studying interactions of hydrogen with metals. In the present work, we studied hydrogen-induced buckling of thin Pd films deposited on various substrates with different bonding strengths (sapphire, glimmer) and also the effect of deposition temperature. Lattice expansion and phase transitions were invest...

Hydrogen interaction with defects and structural development of Pd films with various microstructures were investigated. Nanocrystalline, polycrystalline and epitaxial Pd films were prepared and electrochemically loaded with hydrogen. Structural changes of Pd films caused by absorbed hydrogen were studied by in-situ X-ray diffraction combined with...

The development of the microstructure in nanocrystalline, polycrystalline and epitaxial Pd films loaded with hydrogen is investigated. Structural changes in Pd films loaded with hydrogen were characterized by positron annihilation spectroscopy combined with electron microscopy and X-ray diffraction. It was found that hydrogen charging causes plasti...

Hydrogen absorption and diffusivity in high quality ZnO crystals were investigated in this work by X-ray diffraction combined with slow positron implantation spectroscopy and electrical resistometry. ZnO crystals were covered by a thin Pd over-layer and electrochemically charged with hydrogen. It was found that absorbed hydrogen causes plastic defo...

In the present work hydrothermally grown ZnO single crystals were electrochemically charged with hydrogen. The influence of hydrogen on ZnO microstructure was investigated by positron annihilation spectroscopy (PAS) combined with X-ray diffraction (XRD) using synchrotron radiation. Hydrogen concentration in the samples was determined by nuclear rea...

Hydrogen absorption in Pd causes a significant volume expansion. In free-standing bulk Pd, the hydrogen-induced volume expansion is isotropic. However, the situation becomes more complicated in thin Pd films. Contrary to bulk samples, thin films are clamped to an elastically stiff substrate, which prevents in-plane expansion. Hence, the volume expa...