《印制电路材料与工艺》课程教学改革与探索

本文从《印制电路材料与工艺》课程的教学目的出发,分析、探讨了教学过程中存在的问题,通过将教学内容与PCB行业技术发展相融合、整合教学资源与教学方法、采取多样化的考核方式、以及开辟多种渠道以培养学生实践与创新能力等方面,对课程教学进行了改革与探索。     

水力条件对污泥颗粒化过程的影响、控制与表达研究进展

颗粒污泥具有沉降速度快、生物浓度高、污泥产率低等优点,自被发现以来就引起了国内外研究者的广泛关注。当前已有大量针对污泥颗粒化条件及其影响机制的研究,其中反应器水力条件是被广泛接受的影响污泥颗粒化的关键因素。对现有的关于水力条件对好氧和厌氧颗粒污泥形成与稳定性影响的研究结果进行了分析,发现颗粒污泥形成与稳定必须控制在一定的水力条件范围内,但不同研究平台的结果难以统一,其原因是影响水力条件的因素非常复杂。进而,对现有水力条件控制与表达的方式进行汇总,从微观层面解析了不同控制方式对水力条件的影响机制,分析了当前水力条件表达还存在比较宏观或难反映局部特征的问题,而近年被引入反应器水力条件研究的计算流体力学的方法,将在污泥颗粒化水力条件精确表达方面发挥重要作用。通过对污泥颗粒化过程水力条件影响、控制与表达的回顾、总结、分析及发展预测,为后续的研究提供参考。      

溶胶-凝胶法制备晶粒择优取向铁电薄膜的研究

本文综述了用溶胶－凝胶法制备择优取向铁电薄膜的工艺方法、特点和机理的最新研究进展；详细分析溶胶－凝胶法制备择优取向铁电薄膜的影响因素，探讨了晶粒择优取向生长的机理。     

钛酸钡基厚薄膜PTCR的研究

介绍了钛酸钡基厚、薄膜PTCR的制备方法与研究进展。射频磁控溅射和溶胶-凝胶成膜技术是制备陶瓷PTCR薄膜的较理想的方法。陶瓷PTCR厚膜技术由于具有成本低和较好的市场前景受到人们的高度重视。目前钛酸钡基PTCR厚、薄膜技术的研究已经取得了较大的进步和发展。PTCR膜材正向着低室温电阻、高升阻比和集成化的方向发展。     

高施主掺杂还原再氧化钛酸钡陶瓷的阻温特性研究

通过还原后在空气中热处理氧化的方法制备热敏陶瓷层的高浓度La施主掺杂BaTiO3陶瓷以获得温度热敏半导化陶瓷热敏层。样品在火焰中快速热处理形成半导化层。由于氧空位处于不稳定态,该样品在空气中经过850℃2 h热处理后氧化。与未掺杂Mn的样品比较,掺杂了Mn的样品在比较低的温度下出现PTC效应和具有大的PTC效应。从退火处理的半导化陶瓷层的PTC特性与相同组分陶瓷的介温特性比较看出,相变和氧吸附均是产生PTC效应的主要原因。     

Adsorption property of citrate dispersant on BaTiO3 particles in aqueous solution

Dispersion behavior of ultra fine BaTiO3 particles in the aqueous solution of ammonium citrate （NH4-CA） or citric acid lanthanum chelate （NH4-La-CA） was investigated. The dispersion property was characterized with sedimentation value. It is easier to obtain well dispersed slurry with NH4La-CA than NH4-CA. In an attempt to better understand the role of citric acid radical, simulation of the dispersant adsorption on BaTiO3 particle was performed with universal force field （UFF）. It is demonstrated that the interaction between citric acid radical and BaTiO3 particle surface is a weak chemical adsorption. Trivalent citric acid radical is adsorbed on BaTiO3 particle surface with maximal adsorption energy. And, larger molecules of NH4-La-CA formed by adding La^3＋ lead to better dispersion property than NHn-CA.     

Dispersing and doping of BaTiO<Subscript>3</Subscript> powder by adsorption

Dispersing and doping of BaTiO3 powder by adsorption method were investigated. Ultrafine BaTiO3 powders were dispersed in the aqueous with ammoniumized citrate （NHa-CA） or ammoniumized citric lanthanum chelate （NH4-La-CA） as dispersant by ultrasonic bath. Better dispersion of BaTiO3 slurry was obtained in the aqueous with NH4-La-CA than that of NH4-CA when the mass ratio of citric acid （CA） to BaTiO3 was less than 0,007. The pH value hardly affects the dispersion property of BaTiO3 suspension dispersed by NH4-La-CA. BaTiO3 powder could be well dispersed （median size D50=0.45 μm） and also doped with high uniformity of added components by adsorbing citric acid chelate on surface. Compared with solid mixing, better microstructure and properties of La/Mn codoped ceramics were obtained by adsorption method.