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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
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    Mechanical Characterizations of Saxidomus purpuratus Shells

    W. YangY. JiangG.P. ZhangY.S. Chao...
    601-604页
    查看更多>>摘要：A sort of biological shells (Saxidomus purpuratus), which belongs to Bivalve, was selected as the target material, and hardness and dynamic three point bending fatigue tests were conducted to examine its mechanical properties. Microhardness measurements showed that the inner layer is the hardest. The indentation on the specimen with a lower bending strength was damaged more seriously by the same load. Three point bending fatigue tests demonstrated that this kind of the shells with a special structure comprising mineral and organic matrix can experience the repeated loads instead of immediate breaking. The fatigue results on a single shell investigated here indicated that the fatigue strength is usually less than the static bending strength. Most of the fatigue lives of the specimens are less than 2×10~5 cycles. In addition, fatigue fracture surfaces are observed by scanning electron microscopy.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Mineralization of Bone-like Apatite in Chitosan Hydrogel

    Baoqiang LiYanming HuangYongliang WangYu Zhou...
    605-608页
    查看更多>>摘要：Polymers with negative charge groups, such as carboxylic or phosphatic groups, were frequently used to induce or promote the apatite deposition. However, chitosan with potentially chelated calcium ions, were ignored. Inspired by layer by layer technology, chitosan hydrogel without any surface modification process was used as framework to mineralize bone-like apatite. XRD and IR results shown that in situ synthesis bone-like apatite, similar to apatite in rib of rabbit, was carbonate ions partially substituted apatite and preferred growth orientation in direction of their c-axis. Bone-like apatite with nano-flake shape with size of 1um fully covered chitosan in short period of time. In case of chelation effect of amino groups, chitosan hydrogel provided heterogeneous apatite nucleation sites, which supported by fact that bone-like apatite tended to deposit on porous wall of chitosan, rather than grow in form of free-standing.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Comparative Study of Biomorphic Silicon/Silicon Carbide Ceramic from Birch and Compressed Birch

    Zili YanJie LiuJianchun ZhangTian Ma...
    609-612页
    查看更多>>摘要：Wood compression process was innovatively introduced as a pre-treatment method to birch into the fabrication of biomorphic silicon/silicon carbide (Si/SiC) ceramic with high density. Firstly, birch blocks were compressed to the density in the range of 0.85-1.00g/cm~3. Secondly, both birch blocks and compressed birch blocks were carbonized at 1200℃ to get carbon templates. Lastly, carbon templates were infiltrated with liquid silicon to obtain biomorphic Si/SiC ceramics. The effect of compression process on the density and microstructure of both carbon template and ceramic was investigated. The results show that the maxium density of biomorphic Si/SiC ceramic from compressed birch is 3.01g/cm~3, whereas the density of the ceramic from birch is only 2.80-2.89g/cm~3. So the compression process was an effective method to increase the density of biomorphic Si/SiC ceramic.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    In Vivo Study of Carbon Artificial Femoral Head

    Lan ChenXiaobing YuanHongwei SunMingzhao Chen...
    613-616页
    查看更多>>摘要：Hip hemiarthroplasty is a popular method for curing hip joint diseases. Comparing with the total hip replacement (THR), hip hemiarthroplasty has some advantages, such as simpler operation, lower cost and less injury. However, inevitable acetabular cartilage wear, which leads to ultimately conversion to THR, has been reported by many authors. That limits its applications. To solve this problem, more suitable biomaterial should be chosen to make the femoral head. In this research, a kind of carbon femoral head, which was made of graphite coated with low temperature isotropic pyrolytic carbon, was studied in vivo. Nineteen New Zealand adult white rabbits were divided into 3 groups. Every rabbit was taken the replacement operation and time-dependently killed after certain periods. X-ray photographs of the hip joint, macroscopic apperarance and histological morphometry of the neocartilage around the prosthesis, were examined. The results proved that the coating material of the femoral head was biocompatible and the neocartilage tissue around the prothetic head might protect the acetabulum from wear. However, because of the complicated physiological environment, further research is needed.
      原文链接:
    • NETL
    • NSTL

    Preparation of Porous HA_w/β-TCP Ceramics with In situ Synthesis of HA Whiskers

    Qingfeng ZanYaocong HanLimin DongChen Wang...
    617-619页
    查看更多>>摘要：Adding whiskers to ceramic was a way that has been used to strengthen the ceramics matrix. For porous materials, strength of pore walls was an important factor for strength of the whole materials. Porous calcium phosphate ceramics were always used as scaffolds of bone tissue engineering because of their biocompatible and osteoconductibility. In this work, HA whiskers were born in the porous β-TCP ceramic during in situ procedure. The HA whiskers with about 2μm for length and 100nm for diameter were observed from SEM photographs of as-fabricated porous HA ceramics, and the phase content was determined by XRD.
      原文链接:
    • NETL
    • NSTL

    Porous β-Ticalcium Phosphate Composite Scaffold Reinforced by K_2HPO_4 and Gelatin

    JinGou JiXiaoYu YuanZhiNing XiaPengPeng Liu...
    620-623页
    查看更多>>摘要：To improve the mechanical strength of porous P-tricalcium phosphate (β-TCP) scaffold, porous β-TCP composite scaffold was prepared by immersing as-sintered porous β-TCP scaffold mixed with K_2HPO_4 in gelatin solution, following vacuum drying and glutaraldehyde cross-linking. The pattern of samples was characterized by X-ray diffraction (XRD). The surfaces of samples were analyzed by scanning electron microscopy (SEM). The compressive strength of samples was measured by universal test machine. The porosity percentage of samples was investigated by Archimedes method. The effects of time of samples incubating in simulated body fluid (SBF) on compressive strength and weight loss of samples were also studied. The results show that the compressive strength and water-retention rate of samples can be improved by the K_2HPO_4 and gelatin. The decrease rate of compressive strength and weight loss of samples is greater initially, and then slower compared with that of β-TCP scaffolds. When the samples incubate in SBF about 45d, the compressive strength and weight become increase, and finally are greater than that of β-TCP scaffold.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    In-situ Templating Synthesis of Thermally Stable Hydroxyapatite with Ordered Nanostructures

    Haifeng GuoFeng YeXiulan HeHaijiao Zhang...
    624-626页
    查看更多>>摘要：Alkyl phosphates, the products from the reaction between phosphorous pentoxide and various alcohols, were used as the in-situ templates of nanostructure as well as phosphorus source of HAP. The obtained precursor samples had ordered nanostructures:lamellar structure for dodecyl and n-octyl phospahes templated samples, cubic for n-pentyl and hexagonal for ethyl phosphates templated samples. The calcined ethyl phosphate templated sample was pure HAP with a specific surface area of 42m~2/g, and sustained with an orderly hexagonal nanostructure at 400℃. But the calcination at 400℃ caused the collapse of other alkyl phosphates templated nanostructures.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of Carbon Fiber Reinforced Si-HA Bone Cements Composites

    Li Juan-YingHuang Jian-FengCao Li-Yun
    627-629页
    查看更多>>摘要：Carbon fiber reinforced silicon-substituted hydroxyapatite (C_(f)/Si-HA) bone cements composites were prepared by microwave chemical reaction with a later solidification process using carbamide, calcium nitrate, ammonium dibasic phosphate and ethyl silicate as raw materials, and buffer solutions of acrylic acid and itaconic acid as gelling agent. The influences of carbon fibers volume fraction, contents of coupling agents, sodium citrate contents on the flexural strength of silicon-substituted hydroxyapatite bone cements composites were particularly investigated. The phase composition, microstructures and flexural strength of the composites were characterized by X-ray diffraction, scanning electron microscope and universal testing machine analyses. And the flexural strength of the prepared composites reach the maximum value 41.5MPa when the carbon fibers volume fraction, silane agent KH550 and sodium citrate mass fraction arrive to 3.0, 0.6 and 3.0%, respectively.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    An Implantable CPW-fed Antenna on the MgTa_(1.5)Nb_(0.5)O_6 Ceramic Substrate

    Hung-Chi YangTsung-Fu ChienChien-Min ChengKai-Huang Chen...
    630-633页
    查看更多>>摘要：An implantable antenna for the applications of biomedical telemetry has been widely studied in the modern medical science. The purpose of this study is to design and fabricate an implantable antenna which exhibits enhanced bandwidth (25%) and miniaturization for the use of implantation. In this letter, the microwave dielectric ceramic (MgTa_(1.5)Nb_(0.5)O_6) substrate which possesses high dielectric constant (ε_r= 28) and high quality factor is used as the substrate of the implantable antenna, a CPW-fed monopole dual spiral structure is adopted as the antenna pattern and fabricated by the print-screening technique. The effects of shape, length, size, and thicknesses of the proposed antenna would be evaluated and investigated in this letter. In addition, the center frequency is required to conform to the band (402 ～ 405 MHz) provided by Medical Implant Communication Services (MICS). From the experimental results of the proposed antenna immersed in phantom fluid, the optimum antenna exhibits a miniaturized volume of 288 mm~3, bandwidth of 134 MHz (33%), return loss -16.32 db at 404 MHz, the SAR of 142 W/Kg, and gain of-16 db, respectively.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Ceramic Coatings of Magnesium Alloy for Biomaterial Applications

    Zhang PuliangLiu BinZhang DongTao Yongwei...
    634-637页
    查看更多>>摘要：Ceramic coatings were produced on magnesium (Mg) alloy of AZ91D for biomaterial applications by micro-arc oxidation (MAO) and electrodeposition methods. The morphology, microstructure, phase composition and corrosion properties of the prepared coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and potentiodynamic polarization tester, etc. The results indicated that a porous oxide layer was grown on the Mg alloy sheets after MAO process and the compositions of oxides were mainly Mg_2SiO_4 and MgO. After further electrodeposition and alkaline treatment, a flake-like structure diverging from centre to periphery was grown on the MAO coating and the coating was mainly made up of hydroxyapatite (HA). Moreover, the corrosion resistance of the Mg alloy after being treated with MAO and electrodeposition technique increases obviously, which was evaluated in stimulated body fluid (SBF).
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd