Parametric studies of multi-material laser densification

Fabrication of multi-material components via a laser-assisted layer-by-layer fabrication process has been numerically simulated and analyzed using a three-dimensional thermo-mechanical model. Effects of the chamber preheating temperature, laser scanning rate, initial porosity and thickness of each powder layer on the out-of-plane warping and residual thermal stresses of a nickel/porcelain workpiece have been investigated. It is found that warping and residual thermal stresses of the laser-densified multi-material workpiece are more sensitive to the chamber preheating temperature and the thickness of each powder layer than to the laser scanning rate and the initial porosity of the powder layer. The major mechanism responsible for these phenomena is identified to be related to the change of the temperature gradient induced by these laser processing parameters.     

陶瓷／金属梯度热障涂层的制备及性能评价

为了评价陶瓷／金属梯度热障涂层的性能，设计了4种涂层方案和2种基体材料（1Cr18Ni9Ti和2Cr13）．利用单枪单送粉器成功地制备了线性梯度涂层．通过观察涂层的微观结构、测量涂层的抗热震性能和热残余应力来评价涂层的性能．利用扫描电镜对各种陶瓷涂层的微观结构进行了观察和分析，利用X射线能谱分析得到了陶瓷梯度涂层试样中的不同区域的衍射图．热震试验表明，梯度涂层比非梯度涂层具有更好的抗热震性能．采用钻孔法对不同涂层方案进行了残余应力的测量，结果表明，压应力出现在1Cr18Ni9Ti基体材料上，而拉应力出现在2Cr13基体材料上．     

Fabrication of GaN films through reactive reconstruction of magnetron sputtered ZnO/Ga_2O_3

1　INTRODUCTIONGallium nitride (GaN) is one of the most po tential semiconductors. GaN has a direct energyband gap of 3.4 eV at room temperature and highexternal photoluminescence quantum efficiency, aswell as a high excitonic binding energy of20 meV[1]. It is an ideal material for fabrication ofultraviolet(UV)/blue/green light emitting diodes(LEDs), laser diodes(LDs), UV detectors and de vices operating in high temperature, high frequen cy and high power co…     

透明导电氧化物薄膜及其制备方法

综述了透明导电氧化物(TCO)薄膜的特性、应用及制备技术的发展,重点讨论了磁控溅射、脉冲激光沉积、溶胶-凝胶、喷射热分解等制备技术和柔性衬底TCO薄膜的制备状况、进展及发展趋势,并指出改进TCO薄膜制备技术的努力方向应体现完善薄膜性能、降低反应温度、提高控制精度、降低制备成本和适应集成化等趋势,而制备方法的选择则应根据薄膜的性能要求和不同的应用目的而不同.     

实验大鼠脑缺血模型的制作及效果评价

缺血性脑血管病是临床上常见的一类疾病，其致残率和死亡率均较高。采用一种线栓法，制备大鼠局灶性脑缺血再灌注模型，并从动物神经病学评分、鼠脑整体观、鼠脑切面氯化三苯四氮唑染色、鼠脑组织光镜下观察等进行评价，表明该模型达到脑缺血的效果。在此基础上可进行缺血性脑血管病的多种实验性研究。     

Silicon-based miniature sensor for electrical tomography

The paper describes the fabrication of a novel miniature sensor for electrical tomography. The sensor comprises a number of copper electrodes that are fabricated around a small hole that is etched through a silicon wafer. Copper electrodes are electroplated to fill channels that are formed in thick photo-resist on top of the silicon wafer. Electrodes with a thickness of 60 μm, surrounding a hole of diameter 300 μm, have been realised. Initial measurements have been made using a commercial LCR meter applied to an eight-electrode sensor and images of a 80 μm diameter wire have been obtained. Future work will consider the integration of measurement circuitry alongside the electrodes in order to reduce parasitic capacitances.     

三元复合管道的制备工艺

为解决现有复合管道在腐蚀与磨损共存工况下使用的寿命短问题,研制了耐磨耐蚀型三元复合管道.该新型复合管道是由金属、陶瓷、聚合物三层材料组成,通过反应加工工艺和反应浸渍工艺复合而成.对新制品在不同腐蚀介质和温度下的耐蚀性能进行了表征分析和评价,应用实例证明,三元复合管道具有优异的耐磨耐蚀性能和防磨阻垢功能,尤其在复合腐蚀、冲蚀磨损、高温运行和负压工况等复杂条件下具有使用寿命长和性格比高等优点.     

磁控溅射技术新进展及应用

主要简介了磁控溅射技术的基本原理、基本装置、近年来出现的新技术(多靶磁控溅射技术、磁场扫描法、非平衡磁控溅射、脉冲磁控溅射技术、磁控溅射技术与其它成膜技术相结合等),以及国内外利用磁控溅射技术在多层膜和化合物薄膜制备方面取得的一些成果.     

镁基复合材料制备技术、性能及应用发展概况

镁基复合材料因其轻量化和高性能而成为当今高新技术领域中最富竞争力和最有希望采用的复合材料之一.全面综述了常用镁基复合材料研究概况、制备技术、性能及应用前景,并指出了今后的研究方向.     

壳牌气化技术中关键设备压力容器的制造与检验(一)

根据煤气化装置中最重要的设备———气化关键设备压力容器的制造实践,综合论述了该设备的主要制造工艺、检验和试验的要点