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铁基微波吸收粉体材料制备与表征研究
Alternative TitlePreparation and Characterization of Iron-based Microwave Absorbing Powder Materials
尹春雷
Subtype博士
Thesis Advisor袁方利
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline化学工程
Keyword吸波   羰基铁粉   机械球磨   铁基合金   空心
Abstract摘 要 微波吸收材料作为一种重要的功能材料,既具有重要军事意义,又具有广阔民用市场。高性能微波吸收材料的研究目标可以用四个字概括,即薄、轻、宽、强。铁基微波吸收材料饱和磁化强度高,通过引入形状各向异性可以突破Snoek限制,使其具备更高的磁导率,吸波能力显著强于铁氧体;同时居里温度高,能够在较高温度工作。这类微波吸收材料不仅具有良好的电磁参数,而且可以通过调节微粉的粒度和组成、改变形貌和结构、与其他材料复合等多种手段来达到调节电磁参数的目的,有利于进行阻抗匹配和展宽吸收频带。 本文的研究目标是,开发用于超薄吸波涂层(厚度1 mm以下)的高性能微波吸收材料。为了实现这一目标,开展了以下研究: (1)片状羰基铁粉制备及表征。通过高能机械球磨的方法制备片状羰基铁粉,对制备的片状羰基铁粉的形貌、晶体结构、松装密度、氧含量、电磁参数及反射率进行了表征,系统研究了球磨方式、球磨频率、球磨时间、球料比等工艺参数对铁粉性能的影响。机械球磨制备的片状羰基铁粉与原始羰基铁粉相比,磁导率显著提高,有利于增大电磁波损耗;同时介电常数也增大,需要进一步调控以改善阻抗匹配性能。 (2)片状羰基铁粉表面处理。在前期制备片状羰基铁粉的基础上,研究了包覆硬脂酸、包覆二氧化硅、二氧化碳钝化处理、深冷处理以及退火处理对铁粉性能的影响。包覆硬脂酸和包覆二氧化硅可以在保持较高磁导率的同时,显著降低介电常数,从而改善阻抗匹配性能,进而提高了吸波性能。采用二氧化碳钝化高活性的片状羰基铁粉,既显著提高了片状羰基铁粉的抗氧化性能,又保持了片状羰基铁粉的吸波性能,同时具有操作简便、不会过度氧化的优点。综合上述研究成果,制备的片状羰基铁粉性能已初步达到高端应用要求,为客户提供初期样品10 kg。 (3)片状铁基合金粉制备及表征。通过高能机械球磨方法制备了FeNiMo、FeNi、FeSi、FeSiCr四种片状铁基合金粉末,比较了这四种铁基合金粉末和羰基铁粉的吸波性能及抗氧化性能。片状FeSi、FeSiCr合金粉末具有较好的吸波性能,同时具有优异的抗氧化性能。 (4)空心羰基铁粉制备及表征。采用孔蚀法制备空心羰基铁粉,既能减小其松装密度,同时能提高其吸波性能,同时该方法具有操作简便,易于大规模制备的优点。吸波性能提高的原因:一是部分消除了趋肤效应。二是电磁波在刻蚀后空心球内壁的多次反射,导致反射后微波的相互干涉,从而增加了电磁波能量损耗。
Other AbstractAbstract Microwave absorbing materials, as important functional materials, not only have an important military significance, but also have broad civilian market. The research objectives of high-performance microwave absorbing materials can be summarized in four words, which are thin, light, wide and strong. Iron-based microwave absorbing materials have higher saturation magnetization than ferrites and can break Snoek’s limit through the introduction of shape anisotropy, so the flaky iron-based magnetic particles could have large values of microwave permeability and significantly stronger microwave absorption properties than ferrites. Meanwile iron-based microwave absorbing materials have high Curie temperature, so the materials can work at a relatively high temperature. This kind of microwave absorbing materials not only have good electromagnetic parameters, and the electromagnetic parameters can be changed by adjusting the size and composition of the powders, morphology and structure and combing with other materials, that can benefit impedance matching and broadening the absorption band. The goal of this study is to develop high-performance microwave absorbing materials for super-thin (below 1 mm) absorbent coating. To achieve this goal, the following researches were accomplished: (1) Preparation and characterization of flaky carbonyl iron powder. The flaky carbonyl iron powder was prepared by high energy mechanical milling method and the morphology, crystal structure, apparent density, oxygen content, electromagnetic parameters and reflection loss of the prepared flaky carbonyl iron powder were characterized. The relations of milling way, milling frequency, milling time and ratio of grinding media to material to the performance of the flaky carbonyl iron powder were studied systematically. Compared with the original carbonyl iron, the permeability of the flaky carbonyl iron powder was significantly improved, that favors increase of the electromagnetic wave loss; but the permittivity was also increased at the same time, that need for further control in order to improve impedance matching performance. (2) Modification of the flaky carbonyl iron powder. On the basis of pre-preparation flaky carbonyl iron powder, the influences of coating with stearic acid, coating with silica, passivation with carbon dioxide, cryogenic treatment and annealing were studied. Coated with stearic acid or coated with silica can maintain high permeability and significantly reduce permittivity simultaneously, so the impedance matching and microwave absorption performance were improved. Passivation with carbon dioxide can significantly increase the antioxidation properties of the flaky carbonyl iron powder, while maintain the microwave absorption properties. And this method has several advantages: easy to operate and no excessive oxidation. According to the research results, the performance of the prepared flaky carbonyl iron powder has reached the high-level application requirements and 10 kg samples were provided to the customers. (3) Preparation and characterization of flaky iron-based alloy powder. The flaky FeNiMo, FeNi, FeSi, and FeSiCr powders were prepared by high energy mechanical milling method. The microwave absorption and antioxidant properties of these four iron-based alloy powders were compared with carbonyl iron powder. The flaky FeSi and FeSiCr powders have good absorption properties and excellent antioxidation properties. (4) Preparation and characterization of hollow carbonyl iron powder. Hollow carbonyl iron powder was prepared by pitting corrosion method. The apparent density decreases while the microwave absorption performance can be improved. The possible reasons of the improvement of absorption properties are elimination of the skin effect and interference of multiple reflections of microwaves in the inner wall of hollow microspheres.
Pages114
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8290
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
尹春雷. 铁基微波吸收粉体材料制备与表征研究[D]. 中国科学院研究生院,2013.
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