The nano-TiO2 microspheres were prepared by a hydrothermal method with urea in ethanol/water solution in the presence of sodium sulfate. The prepared samples were characterized by X-ray diffraction, transmission electron microscopy, N-2 adsorption-desorption and UV-Vis diffuse reflectance spectroscopy, the effects of hydrothermal temperature on the nano-TiO2 microspheres morphology were investigated, and the photocatalytic activities toward gaseous benzene of the samples were studied. The results indicate that the microspheres are composed of tiny nanoparticles, the TiO2 microspheres pose high specific surface areas and uniform porous nanostructures, the optical absorption edges of the samples have "blue shift". The photocatalytic results confirm the benzene-degrading effectiveness of the TiO2 microspheres, especially, the results show that no benzene detected after 20 min reaction with TiO2 microspheres prepared at 180 degrees C, however, the produced CO2 concentration continues to increase, it indicates that TiO2 microspheres with very high adsorptive capacity can enhance the subsequent photocatalytic reaction, and the mineralization ratio of this TiO2 microspheres can be as high as 5. 5, which is double of P25 (2. 7).
为实现螺旋碳纳米线新型微纳米机器人磁场驱动运动,开展了螺旋碳纳米线截断、磁性修饰及磁场驱动运动研究.提出硝酸氧化-超声振动-滤纸过滤的长度截断筛选方法,实现了螺旋碳纳米线分散且可控截取长度2～8μm.实验对比研究了磁控溅射镍、化学镀镍、水热法生长Fe3 O4纳米颗粒的磁性修饰方法.通过扫描电子显微镜、能量色散X射线谱分析等方法对修饰效果进行了评价,获得了具有较强磁性的螺旋碳纳米线.微流道液体中磁场驱动特性实验表明:磁控溅射修饰的螺旋碳纳米线可实现较为快速(3.35μm/s)的微纳米机器人运动特性,轨迹运动精度可控小于5μm.
以中间相沥青基炭纤维为增强相,热解炭与树脂炭为基体,采用化学气相沉积与液相浸渍-炭化补充增密工艺制备了高导热炭纤维改性C/C复合材料,研究了不同热处理温度(2 000和3 000 ℃)材料的微观结构、力学与导热性能.结果表明,经2 000 ℃处理后,高导热炭纤维与热解炭结构变化不明显,且热解炭与炭纤维界面结合紧密,结合处未形成裂纹等缺陷;当热处理温度提升至3 000 ℃时,高导热炭纤维与热解炭石墨化度明显升高,且炭纤维与热解炭的界面结合处均产生了较明显的微裂纹缺陷.高导热炭纤维改性C/C复合材料经2 000℃处理后,其弯曲强度与室温热导率分别为101.81 MPa和14.739 W/m·K;当热处理温度升高至3 000 ℃时,材料的弯曲强度降低为49.35 MPa,热导率提升为63.568 W/m·K.材料弯曲强度的降低与热导率的增加主要与3 000 ℃处理后,材料内各炭相的石墨化度提升有关.
壳聚糖是一种来源丰富、无毒无害的天然吸附材料,对污水中Cr(Ⅵ)有较好的吸附效果.介绍了Cr(Ⅵ)在水溶液中的存在形式、分析了壳聚糖吸附Cr(Ⅵ)的机理,综述了化学改性和复合改性两类壳聚糖的研究进展.详细介绍了交联改性壳聚糖、接枝改性壳聚糖、有机材料复合改性壳聚糖、磁性材料改性壳聚糖、复合载体材料改性壳聚糖的结构、活性官能团类别、吸附原理和应用.最后对改性壳聚糖的新材料研发、制备工艺优化、应用拓展等研究方向进行了展望.
高Bs铁基纳米晶合金(high Bs nanocrystalline alloys,HBNAs)具备高磁导率、低高频铁损和近零的磁致伸缩,是制备高性能小型电子元器件的理想材料.一直以来,铁基纳米晶合金的Bs受限于合金成分中Fe含量的高低,而如何掌控非晶前驱体的非晶形成能力(glass forming ability,GFA)和后端的电磁性能之间的平衡点,是推动HBNAs进一步发展的关键难题.在回顾Fe基纳米晶软磁合金发展历程的基础上,系统阐述了纳米晶的晶化热力学与动力学、晶化机制和高Bs铁基纳米晶合金非晶形成能力改善方法的现有认识.通过分析高Bs铁基纳米晶合金制备的研究现状及亟待解决的问题,以期为高Bs铁基纳米晶软磁合金成分的开发、退火工艺的设计提供一定的启发和技术思路.
