【作者】 赵凌；

【导师】 胡文彬；

【作者基本信息】 上海交通大学 ， 材料学， 2007， 硕士

【摘要】 由于空心结构的超细粉末与相应的实心粉末相比具有更大的比表面积、较小的密度以及特殊的力学、光、电等物理化学性质而表现出极大的应用前景。近年来,具有空心结构的超细粉末的制备和应用成为材料研究中的一个热点。本文在采用自催化还原模板法制备超细空心镍球的基础上,对所制备的超细空心镍球进行了电磁性能分析,并重点研究了超细空心镍球-聚乙烯缩丁醛(PVB)混合体的微波吸收性能,从而探索了其在微波吸收性涂层中的应用.研究认为,平均粒径为1.2μm的空心镍球混合体无论是从最小反射损耗来看,还是从频宽比考虑,都是一种较好的微波吸收材料。此外,本文还探索了超细空心镍球在利用太阳能中的应用。即以金属-电介质涂层模型为基础,以超细空心镍球作为内部分散金属颗粒,以丙烯酸树脂作为电介质涂层,以铝板作为基体,用浸沾法制备出太阳能光谱选择性涂层。本文考察了改涂层在紫外-近红外和中红外区的光吸收性能,以及空心镍球的粒径度和涂层厚度对光吸收性能的影响。实验可得,超细空心镍球的粒径的减小会使涂层吸收率增大,但不会引起发射率的变化;涂层厚度的增大,会导致发射率的增大,对于吸收率的影响存在一个临界厚度,当涂层厚度小于临界厚度时,随着厚度的增加,吸收率增大,当涂层厚度大于临界厚度时,吸收率随厚度的增大而略有减小。为进一步提高超细空心镍球的磁性能,本文采用化学镀法在空心镍球的表面包覆了磁性能更好的多孔结构的钴层,从而提高了镍球的磁性能和微波吸收性能,拓宽了超细空心镍球的应用领域,使表面改性后的镍球在制备高效、轻质、宽频、超薄的微波吸收涂层中具有广阔的应用前景。本文对改性涂层的形貌、结构、成分、比表面积、电磁性能、微波吸收性能等进行了分析测试。更多还原

【Abstract】 In recent years, increasing interest has been given to the synthesis of submicrometer-sized materials with hollow structures, such as nanotube, submicrometer hollow spheres, which often exhibit novel properties dramatically different from their solid counterparts in the fields of chemistry, physics, biotechnology, and material science.Recently, we fabricate submicrometer-sized nickel hollow spheres(NHSs) by a facile autocatalytic reduction method. In this paper, we analyze the electromagnetic properties of NHSs, and investigate the complex permittivity , permeability and the microwave absorption properties of the composite samples prepared by homogeneously mixing the nickel powders with polyvinyl butyral (PVB) to explore the application of NHSs in microwave absorption materials. The study shows that the composite of NHSs with average diameter 1.2μm exhibits better microwave absorption property and broader bandwidth. Additionally, we also explore the application of NHS in building solar selective absorption materials. Basing on the metal-dielectric medium model, we use NHSs as the dispersion metal particles, acrylic resin as the dielectric medium, aluminium sheet as the basal body to fabricate the solar selective absorption coating by dipping method. We study the solar absorption properties of NHSs in UV-Visible-IR wavelength range and the effects of the particle sizes and the thickness of the coatings on solar selective absorption. It is investigated that with the decrease of particle sizes, the absorptivity will be increased and the emissivity will remain unchanged. Meanwhile, when the coating thickness is increased ,the emissivity will be enhanced as a result. However, when the thickness value exceeds the threshold, the emissivity will be decreased.In order to improve the magnetic performance and microwave absorption properties of the NHSs, we coat the NHSs surface with porous Co shells by更多还原