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Wang Q.-D.,Shanghai JiaoTong University | Gao Y.,Shanghai JiaoTong University | Gao Y.,Grikin Advanced Materials Co. | Yin D.-D.,Shanghai JiaoTong University | Chen C.-J.,Shanghai JiaoTong University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2010

Characterizations of phases in Mg-10Y-5Gd-2Zn-0.5Zr (WGZ1052) alloy during heat treatments were investigated by OM, XRD, SEM and EDS. The mechanisms of microstructure evolution were discussed. The results show that, after high temperature heat treatments, the Mg12ZnY phases still exist. During solution-treatment at 535 °C, the amount of the long-period stacking order structures decreases. At 545 °C for 20 h and 24 h, there are still remnant Mg12ZnY compounds in the Mg matrix, the shape of which does not change and the amount does not decrease obviously. © 2010 The Nonferrous Metals Society of China.

Li J.,Grikin Advanced Materials Co. | Zheng Y.,China University of Petroleum - Beijing | Cui L.,China University of Petroleum - Beijing
Journal of Materials Engineering and Performance | Year: 2010

Incomplete martensitic transformation characteristics of NiTi shape memory alloys after cold deformation were studied. By designing the shape of the original surface curve, macroscopic domains with different dislocation density were introduced into the NiTi alloys and materials possessing the characteristics of composites were obtained. Due to the interactions between the dislocation texture and martensite variants, the reverse transformation temperatures were found to expand over a large temperature window, which gives temperature memory effect a higher potential for application. © ASM International.

Wang Z.,Grikin Advanced Materials Co. | Wang Z.,Chongqing University of Technology | Huang W.,Chongqing University of Technology | Ma Y.,Chongqing University of Technology
Materials Science and Engineering C | Year: 2014

The micro-scale abrasion behaviors of surgical implant materials have often been reported in the literature. However, little work has been reported on the micro-scale abrasive wear behavior of Ti-25Nb-3Mo-3Zr-2Sn (TLM) titanium alloy in simulated body fluids, especially with respect to friction pairs. Therefore, a TE66 Micro-Scale Abrasion Tester was used to study the micro-scale abrasive wear behavior of the TLM alloy. This study covers the friction coefficient and wear loss of the TLM alloy induced by various friction pairs. Different friction pairs comprised of ZrO2, Si3N4 and Al 2O3 ceramic balls with 25.4 mm diameters were employed. The micro-scale abrasive wear mechanisms and synergistic effect between corrosion and micro-abrasion of the TLM alloy were investigated under various wear-corrosion conditions employing an abrasive, comprised of SiC (3.5 ± 0.5 μm), in two test solutions, Hanks' solution and distilled water. Before the test, the specimens were heat treated at 760 °C/1.0/AC + 550°C/6.0/AC. It was discovered that the friction coefficient values of the TLM alloy are larger than those in distilled water regardless of friction pairs used, because of the corrosive Hanks' solution. It was also found that the value of the friction coefficient was volatile at the beginning of wear testing, and it became more stable with further experiments. Because the ceramic balls have different properties, especially with respect to the Vickers hardness (Hv), the wear loss of the TLM alloy increased as the ball hardness increased. In addition, the wear loss of the TLM alloy in Hanks' solution was greater than that in distilled water, and this was due to the synergistic effect of micro-abrasion and corrosion, and this micro-abrasion played a leading role in the wear process. The micro-scale abrasive wear mechanism of the TLM alloy gradually changed from two-body to mixed abrasion and then to three-body abrasion as the Vickers hardness of the balls increased. © 2014 Elsevier B.V.

Wang Z.,Grikin Advanced Materials Co. | Wang Z.,Chongqing University of Technology | Huang W.,Chongqing University of Technology | Meng X.,Chongqing University of Technology
Materials Science and Technology (United Kingdom) | Year: 2015

The electrochemical corrosion behaviour of biomedical Ti-25Nb-3Mo-3Zr-2Sn (TLM) alloy was investigated in various simulated body fluids at 37±0·5°C utilising potentiodynamic polarisation and current-time curves. The Ti-6Al-4V (TC4) alloy was also investigated to make a comparison. The different simulated body fluids comprised of 0·9%NaCl saline, Hank's and Ringer's solution were employed. The effect of heat treatment on the electrochemical behaviour of the TLM alloy was also considered. It was discovered that all the test specimens were passivated once immersed into the simulated body fluids. It was also found that the TLM alloy has poorer corrosion resistance in Hank's solution, due to the chemical composition of the Hank's. After different heat treated, the TLM alloy had different phases and microstructure, and the corrosion behaviour of the TLM alloy was different. In this study, after the heat treatment of 760°C/1 h/AC+550°C/6 h/AC, the TLM alloy had better corrosion resistance. Owing to the corrosion resistance of the TLM alloy was influenced by numerous factors, such as microstructure and the chemical composition of electrolyte, the corrosion behaviour of the TLM alloy is complex. By comparing with the corrosion behaviour of the TC4 alloy, the TLM alloy has poorer corrosion resistant than the TC4 alloy under the same conditions. But the current-time curves of the TLM alloy were more stable than these of the TC4 alloy with further experiments, because of the more passivation film on the surface of the TLM alloy. © 2015 Institute of Materials, Minerals and Mining.

Kong F.,University of Science and Technology Beijing | Kong F.,Grikin Advanced Materials Co. | Zhang X.,Harvard University | Hai M.,University of Science and Technology Beijing | Hai M.,Harvard University
Langmuir | Year: 2014

We encapsulate the hydrophilic anti-cancer drug doxurubicin hydrochloride (DOX) with about 94% drug encapsulation efficiency, either alone or with nanomagnetite, in monodisperse biocompatible phospholipid vesicles. Glass capillary microfluidics is used to generate monodisperse water in oil in water (w/o/w) double-emulsion templates with a core-shell structure by using a mixture of liquid unsaturated phospholipids and powdered saturated phospholipid. This combination would overcome the low transition temperature of unsaturated powdered phospholipid and the solubility limitation of saturated phospholipid, as well as improving the fabrication of stable monodisperse phospholipid vesicles. The double-emulsion droplet is controlled from 50 to 200 μm according to different flow rates, and the final phospholipid vesicles are retained after a solvent removal step by dewetting. DOX-loaded phospholipid vesicles show sustained release compared with free DOX water solution. The in vitro cell viability of 100 μg/mL phospholipid vesicles on HeLa or MCF-7 cells after 24 h incubation at 310 K is above 90%, confirming the excellent biocompatibility of the phospholipid vesicles. These biocompatible phospholipid vesicles are promising oral drug delivery vehicles for biomedical applications and magnetic resonance imaging contrast agents for biomedical diagnosis. © 2014 American Chemical Society.

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