Marietta, GA, United States
Marietta, GA, United States

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Su Y.-Y.,Amorphous Oxide Technology Inc. | Shih C.-C.,Taipei Veterans General Hospital | Shih C.-C.,National Yang Ming University | Shih C.-C.,University of Taipei | And 6 more authors.
Surface and Interface Analysis | Year: 2010

Wallstent has been successfully used to open up clogged peripheral arteries. Co-Cr alloy is the preferred metal for the construction of wallstent. Unfortunately,major complications such as in-stent intimal hyperplasia,stent obstruction, and stent stricture are often reported, and these complications could be related to the metallic properties of the wallstent. In this study, the electrochemical properties of Co-Crwires from wallstentwere investigated using cyclic polarization, open-circuit potential, potentiostatic condition, and electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray mapping were also employed to investigate the surface morphology and elemental distribution after electrochemical measurement. Results of this study showed the heterogeneous electrochemical properties of Co-Cr alloy wires that could result in severe galvanic corrosion of wallstent after implantation. Severe corrosion process could cause fracture of wallstent, resulting in localized inflammation, allergy, and thicker neointima. Copyright © 2009 JohnWiley & Sons, Ltd.


Su Y.-Y.,Amorphous Oxide Technology Inc. | Shih C.-C.,National Yang Ming University | Shih C.-C.,Taipei Veterans General Hospital | Chen L.-C.,Shin Kong Memorial Hospital | And 3 more authors.
Applied Surface Science | Year: 2012

Different oxide structures can be formed on passive stainless steel sternal wires by various surface modifications. Oxide structure has a significant influence on the efficacy and biocompatibility of the medical devices. In this study, cathodic reduction was used to distinguish the oxide structures on 316L stainless steel sternal wires in a buffered phosphate electrolyte. TEM, Auger depth profile, XPS, and SEM were applied to examine the oxide structures. Interfacial resistance was measured using electrochemical impedance spectroscopy. Results indicate that cathodic reduction profiles have the capability to identify oxide structures on the passivated medical devices. © 2011 Elsevier B.V. All rights reserved.


Morimoto T.,Amorphous Oxide Technology Inc. | Shin Y.,Amorphous Oxide Technology Inc. | Kumai T.,Yoshikawa Kogyo Co. | Yanagimoto J.,University of Tokyo
Tribology Online | Year: 2015

Hard materials were mixed with alloy powders and thermally sprayed at an ultra rapid cooling rate of more than 106°C/s. For example, 65Ni15Cr16P4B at% alloy powder containing tungsten carbide was thermally sprayed. SEM image showed tungsten carbide paticles were scattered in the amorphous alloy coatings. The resulting thermal coatings showed low friction and high wear resistance in a reciprocating-slide-type friction-testing machine because tungsten carbides exhibited cleavage fracture. The stress analysis of an amorphous alloy coating with low friction was also carried out by the finite element method. © 2015 Japanese Society of Tribologists.


Shin Y.,Amorphous Oxide Technology Inc. | Ohmori Y.,Yoshikawa Kogyo | Morimoto T.,Amorphous Oxide Technology Inc. | Kumai T.,Yoshikawa Kogyo | Yanagida A.,Tokyo Denki University
Materials Transactions | Year: 2016

A new thermal spray gun for nitrogen gas cooling and mist cooling has been developed. Aluminum-magnesium alloy films prepared by nitrogen gas cooling using the thermal spray gun had a partial nano microstructure because residual strains induced by rapid cooling acted as solid nuclei and a small amount of the amorphous phase became crystalline as a result of the heat of the thermal spray. Furthermore, the nano- microstructured aluminum magnesium films exhibited high corrosion resistance. Moreover, aluminum-magnesium alloy films containing a small amount of titanium prepared by mist gas cooling exhibited higher corrosion resistance than those without titanium. We consider that the aluminum -titanium compound acted as solid nuclei during ultra rapid solidification and that a strong passive layer was formed by mist gas cooling. © 2016 The Japan Institute of Metals and Materials.


Shih C.-C.,Taipei Veterans General Hospital | Shih C.-C.,National Yang Ming University | Su Y.-Y.,Amorphous Oxide Technology Inc. | Chen L.-C.,National Yang Ming University | And 5 more authors.
Acta Biomaterialia | Year: 2010

Sterilization is an important step prior to the implantation of medical devices inside the human body. In this work we studied the influence of steam sterilization cycles on the oxide film properties of stainless steel sternal wire. Characterization techniques such as open-circuit potential, potentiodynamic measurement, electrochemical impedance spectroscopy, cathodic stripping, transmission electron microscopy, atomic force microscopy and scanning electron microscopy were employed to investigate the cycles of steam sterilization on the corrosion behavior of sternal wire. The results showed that the oxide properties are a function of the number of steam sterilization cycles and deteriorate as the number of cycles increases. Steam sterilization might damage the implant integrity and heavy metals could be released to the surrounding tissues due to deterioration of the oxide film. © 2010 Acta Materialia Inc. All rights reserved.


Su Y.-Y.,Amorphous Oxide Technology Inc. | Nakayama S.,Sumitomo Electric Industries | Osakai T.,Kobe University
Corrosion Reviews | Year: 2011

The determination of oxide thickness via cathodic reduction was developed in 1936. It is a simple laboratory practice that has the sensitivity and capability to analyze total oxide thickness of both cuprous and cupric oxides within the same run. Unfortunately, contradictory results and misidentifi cation of oxide layers on the copper surface have caused ambiguity in the interpretation of many published results, leading to its incorrect use in industrial applications. This review surveys experimental parameters used by the authors, such as electrolyte composition and concentration, current density, current effi ciency, sample history, interfacial impedance, crystalline orientation, and concentration of depolarizer on the cathodic reduction of copper oxides. Ultimately, the goal of the review is to propose solutions by which more precise measurement and correct identifi - cation of oxide layers could be derived from this type of experiment. © 2011 by Walter de Gruyter - Berlin - Boston.


Su Y.-Y.,Amorphous Oxide Technology Inc. | Shemenski R.M.,RMS Consulting Inc.
Materials and Design | Year: 2010

Torsion testing is used to determine the quality of steel wire used for beads in pneumatic tires. However, strain aging (dynamic and static) caused by interstitial carbon and nitrogen atoms bound to mobile dislocations increases yield strength and decreases bead formability. Processing parameters of bead wire, such as line speed, lead bath temperature and wire diameter, were investigated, and theoretical calculations were made to estimate the effect of these parameters on strain aging. Nitrogen concentration was measured in bead wire samples with varying numbers of twists to failure during torsion testing. Surface morphologies of twisted bead wires were examined by scanning electron microscopy. Experimental data showed that torsional properties of bead wire were a function of stress relief temperature on and theoretical calculations showed that line speed and temperature have to be optimized for optimum torsion ductility. © 2009 Elsevier Ltd. All rights reserved.

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