Papers by Author: Lian Cheng Zhao

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Authors: Cheng Xin Lin, Nanju Gu, Lian Cheng Zhao, Qing Suo Liu, Chun Sheng Wen
Authors: Wei Cai, Y. Cheng, Y.F. Zheng, Hong Tao Li, Lian Cheng Zhao
Abstract: Ti-50.6 at.% Ni shape memory alloy was coated with tantalum using multi arc ion-plating technique with the aim to increase its radiopacity and biocompatibility. The surface characteristics were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results of XPS survey spectra show that a thin oxide film are formed inside tantalum coating as a result of natural passivation of Ta in atmosphere. The hemocompatibility was evaluated in vitro by clotting time and platelet adhesion measurement. The results of our study showed that the clotting time of tantalum was higher than that of the TiNi alloys and no sign of accumulation and only slight pseudopodium was observed on the tantalum coatings, suggesting that the tantalum coatings can improve the biocompatibility of TiNi alloy.
Authors: Ailian Liu, Xianglong Meng, Wei Cai, Lian Cheng Zhao
Abstract: The effect of cerium addition on the martensitic transformation behavior and microstructure of Ti50-x/2Ni50-x/2Cex (x=0, 0.5, 2, 5 and 10at.%) alloys have been studied by differential scanning calorimetry (DSC) and energy dispersive spectroscopy (EDS). The results show that the addition of cerium affects the martensitic transformation temperature obviously. With the increase of Ce content, the phase transformation temperatures first increase rapidly and then decrease slightly, which may be attributed to the change of the Ni/Ti ratio in matrix. Moreover, the dispersed Ce-riched second particles with various morphologies are observed in TiNiCe alloys.
Authors: Hong Tao Li, Zhi Jie Sun, Shaojian Ye, Wei Cai, Lian Cheng Zhao
Abstract: Zn,Fe co-doped near stoichiometric LiNbO3 crystals with variant Zn concentrations and with same Fe concentrations were grown by top-seeded-solution-growth (TSSG) method. The optical damage resistances of SLN crystals were studied by the method of transmittance facula distortion. The UV-Vis spectra showed that the grown undoping crystal had a composition very close to stoichiometric LiNbO3 crystal, and the absorption edges moved as the doping concentration changed. The optical damage experiments showed that, the crystal with 2mol% of Zn was with high resistance to optical damage, and the optical damage resistance was improved evidently as the Zn concentration increased further.
Authors: Chun Jiang Li, Yu Feng Zheng, Lian Cheng Zhao
Abstract: The feasibility of using an alternating magnetic field from induction heating furnace to heat the NiTi stent and the influence of hyperthermic on smooth muscle cells (SMCs) have been studied in the present work. The electromagnetic field is capable of significantly heating NiTi stents and the heating temperature can be adjusted by changing the voltage and heating time of the furnace and the position of NiTi stents. The shape and living status of SMCs were influenced by the heat treatment procedures. There were three stages of SMCs reaction to heat: (1) when the temperature below 44°C, the living status was not changed; (2) between 44°C to 50°C, the cells shrinked and were less dyed with trypan blue, which indicated that they were still alive; (3) when the temperature was above the 50°C, all the cells died. It was found that from 44°C to 50°C, the SMCs died in apoptosis, which might allow us to heat the implanted stent to prevent restenosis.
Authors: L. Sun, F.Y. Guo, Q. Lv, Hong Tao Li, Wei Cai, Y.H. Xu, Lian Cheng Zhao
Abstract: In: Eu: Fe: LiNbO3 crystals were firstly grown from a congruent melt according to the Czochralski method, with the various ratios of Li/Nb =0.885, 0.946, 1.051. The new crystal composition and defect structure were analyzed by the UV-Vis spectroscopy. In the two-wave coupling experiments, writing and erasure time, maximum diffraction efficiency, photorefractive sensitivity and dynamic range were measured and calculated. The dependence of the photorefractive properties on the defect structure of In: Eu: Fe: LiNbO3 Crystals were discussed.
Authors: Xiang Long Meng, Yu Dong Fu, Wei Cai, J.X. Zhang, Qing Fen Li, Lian Cheng Zhao
Abstract: The martensitic transformation behavior and shape memory effect (SME) have been investigated in a Ni-rich Ti29.6Ni50.4Hf20 high temperature shape memory alloy (SMA) in the present study. After aging, the transformation temperatures of Ti29.6Ni50.4Hf20 alloy increase obviously due to the precipitation of (Ti,Hf)3Ni4 particles. And the transformation sequence changes from one-step to two-step. When the experimental alloy is aged at different temperatures for 2h, the transformation temperatures increase rapidly with increasing the aging temperature and then change slightly with further increasing the aging temperature. Most of the martensite variants preferentially oriented in the aged Ti29.6Ni50.4Hf20 alloy. The aged Ti29.6Ni50.4Hf20 alloy shows the better thermal stability of transformation temperatures than the solution-treated one because the precipitates depress the introduction of defects during thermal cycling. In addition, the proper aged Ti29.6Ni50.4Hf20 alloy also shows the larger SME than the solution-treated one since the precipitates strengthen the matrix strongly.
Authors: Feng Chen, Wei Cai, Lian Cheng Zhao, Yu Feng Zheng
Abstract: In present paper, the mechanical properties and fracturegraphs of Mn-rich polycrystalline alloys are investigated by compression tests and scanning electron microscope (SEM) observations. It is shown that the fracture strength and the rupture strain decrease with the increase of Mn content. It is suggested that the substitution of Mn for Ga reduces the ductility of Ni-Mn-Ga alloys. SEM observations of fracture surface show us typical intergranular crack. There are many little holes and micro-cracks on the grain boundary, which weakens the bond strength of grain boundary causing the intercrystalline cracking.
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