【作者】 吴甲民；

【导师】 吕文中；

【作者基本信息】 华中科技大学 ， 微电子学与固体电子学， 2012， 博士

【摘要】 在阅读大量文献的基础上,结合科研项目的实际需要,本文以0.9Al2O3-0.1TiO2和90wt.%(0.75ZnAl2O4-0.25TiO2)-10wt.%MgTiO3(ZTM)(?)氐介微波介质陶瓷以及45wt%Ba0.6Sr0.4TiO3-55wt%MgO (BSTM)铁电陶瓷为研究对象,采用凝胶注模工艺制备了这三类陶瓷材料,系统研究了制备方法对这些陶瓷材料相组成、微观结构以及相关性能的影响。首先在简单介绍陶瓷浆料流变学特性及丙烯酰胺凝胶体系凝胶固化原理的基础上,研究了pH值、分散剂以及固相含量对陶瓷浆料的流变学特性的影响,并研究了环境温度、引发剂和催化剂加入量以及单体浓度对陶瓷浆料凝胶固化速率的影响。采用水基凝胶注模工艺和干压法制备了0.9Al2O3-0.1TiO2陶瓷。研究了制备工艺对0.9Al2O3-0.1TiO2陶瓷的相组成、微观结构以及微波介电性能的影响。通过采用合适的粉体预烧温度和连续缓慢的降温处理,消除了Al2TiO5第二相,在最终制备得到的0.9Al2O3-0.1TiO2陶瓷中只存在A12O3和Ti02两相。与干压法相比,采用水基凝胶注模工艺制备的0.9Al2O3-0.1TiO2陶瓷的气孔较少、晶粒较大且分布更加均匀。此外,采用水基凝胶注模工艺制备0.9Al2O3-0.1TiO2陶瓷能够有效改善其微波介电性能。基于分步干燥法和缓慢的排胶制度,采用水基凝胶注模工艺制备了完整的大尺寸、复杂形状的0.9Al2O3-0.1TiO2陶瓷部件。采用水基凝胶注模工艺和干压法制备了ZTM陶瓷。研究了制备工艺对ZTM陶瓷的相组成、微观结构以及微波介电性能的影响。结果表明,无论采用哪种制备方法,制备的ZTM陶瓷的相组成都是一样的。与干压法相比,采用水基凝胶注模工艺制备的ZTM陶瓷的气孔较少、晶粒较大且分布更加均匀。此外,采用水基凝胶注模工艺制备ZTM陶瓷不但可以有效改善其微波介电性能,而且还能够在一定程度上降低其烧结温度。基于分步干燥法和缓慢的排胶制度,采用水基凝胶注模工艺制备了ZTM微波介质天线基板,最后制备出可以满足实际应用要求的GPS天线。采用水基、半水基凝胶注模工艺以及干压法制备了BSTM铁电陶瓷。研究了制备工艺对BSTM陶瓷的相组成和微观结构的影响。结果表明,无论采用哪种制备方法,制备的BSTM陶瓷的相组成都是一样的。同时,采用水基和半水基凝胶注模工艺制备的BSTM陶瓷的微观结构都比较均匀。采用非水基凝胶注模工艺和干压法制备了BSTM陶瓷。研究了制备工艺对BSTM陶瓷的相组成、微观结构以及介电性能的影响。结果表明,无论采用哪种制备方法,制备的BSTM陶瓷的相组成都是一样的。与干压法相比,采用非水基凝胶注模工艺制备的BSTM陶瓷的微观结构更加均匀。此外,采用非水基凝胶注模工艺制备BSTM陶瓷不但能够改善其性能的稳定性,而且还能够在一定程度上改善其介电性能。采用水基凝胶注模工艺辅助固相反应法(AGASSM)与固相反应法(SSM)制备了BSTM陶瓷粉体。研究了陶瓷粉体制备方法对制备的陶瓷粉体的相组成和微观结构的影响。随后采用干压法成型,研究了陶瓷粉体制备方法对最终制备的BSTM陶瓷的相组成、微观结构以及介电性能的影响。结果表明,与SSM相比,采用AGASSM制备的BSTM陶瓷粉体粒径更小(Dav=1.00μm)、呈球状,而且分布更加均匀。无论采用哪种粉体制备方法,制备的BSTM陶瓷粉体以及用该陶瓷粉体干压成型的BSTM陶瓷的相组成都是完全一样的。与SSM相比,采用AGASSM制备的陶瓷粉体干压成型的BSTM陶瓷的微观结构更加均匀。此外,采用AGASSM制备陶瓷粉体可以改善BSTM陶瓷的介电性能,并能够在一定程度上降低其烧结温度。采用改进的水基凝胶注模工艺辅助固相反应法(IAGASSM)、AGASSM和SSM制备了BSTM陶瓷粉体。研究了陶瓷粉体制备方法对制备的陶瓷粉体的相组成和微观结构的影响。随后采用干压法成型,研究了陶瓷粉体制备方法对最终制备的BSTM陶瓷的相组成、微观结构以及介电性能的影响。结果表明,与SSM和AGASSM相比,采用IAGASSM制备的BSTM陶瓷粉体的粒径最小(Dav=0.83μm),而且分布最均匀。无论采用哪种粉体制备方法,制备的BSTM陶瓷粉体以及用该陶瓷粉体干压成型的BSTM陶瓷的相组成都是完全一样的。与SSM和AGASSM相比,采用IAGASSM制备的陶瓷粉体干压成型的BSTM陶瓷的微观结构最均匀。此外,采用IAGASSM制备陶瓷粉体可以显著改善BSTM陶瓷的介电性能,并能够在一定程度上降低其烧结温度。更多还原

【Abstract】 Based on studying lots of relevant research papers and the requirements of our research programs, in this dissertation, the0.9Al2O3-0.1TiO2,90wt.%(0.75ZnAl2O4-0.25TiO2)-10wt.%MgTiO3(ZTM) low-permittivity microwave dielectric ceramics, and45wt%Ba0.6Sr0.4TiO3-55wt%MgO (BSTM) ferroelectric ceramics were prepared by gelcasting. The effects of different preparation methods on the phase compositions, microstructures and relevant properties of the prepared ceramic materials were systematically investigated.Based on the simple introductions for the rheology properties of ceramic slurry and the solidification theory of acrylamide gelcasting system, the effects of pH value, dispersant and solids loading on the rheology properties of ceramic slurry and environmental temperature, initiator and catalyst contents, and monomer concentration on the solidification rate of ceramic slurry were all investigated.The0.9Al2O3-0.1TiO2ceramics were prepared by aqueous gelcasting and dry pressing. The effects of different preparation methods on the phase compositions, microstructures and microwave dielectric properties of0.9Al2O3-0.1TiO2ceramics were investigated. With adopting proper powder calcining temperature and continuous and slow cooling treatment, the Al2TiO5secondary phase is eliminated, and there are only Al2O3and TiO2phases. Compared with dry pressing, there are fewer pores, larger grains and more uniform grain distribution in the0.9Al2O3-0.1TiO2ceramics prepared by aqueous gelcasting. Moreover, adopting aqueous gelcasting to prepare0.9Al2O3-0.1TiO2ceramics could effectively improve their microwave dielectric properties. Based on stepped drying and slow binder removal, some intact, large dimension and complex shaped0.9Al2O3-0.1TiO2components were prepared by aqueous gelcasting.The ZTM ceramics were prepared by aqueous gelcasting and dry pressing. The effects of different preparation methods on the phase compositions, microstructures and microwave dielectric properties of ZTM ceramics were investigated. The results demonstrate that the phase compositions of the ZTM ceramics are the same no matter what preparation method is adopted. Compared with dry pressing, there are fewer pores, bigger grains and more uniform grain distribution in the ZTM ceramics prepared by aqueous gelcasting. Furthermore, adopting aqueous gelcasting to prepare ZTM ceramics could not only improve their microwave dielectric properties effectively, but also decrease their sintering temperature in some extent. Based on stepped drying and slow binder removal, the ZTM microwave dielectric antenna substrates were prepared by aqueous gelcasting, and then a GPS antenna was fabricated, which meets the requirements of real application.The BSTM ferroelectric ceramics were prepared by aqueous gelcasting, semi-aqueous gelcasting and dry pressing. The effects of different preparation methods on the phase compositions and microstructures of the BSTM ceramics were investigated. The results demonstrate that the phase compositions of the BSTM ceramics are the same no matter what preparation method is adopted. Meanwhile, the microstructures of the BSTM ceramics prepared by aqueous and semi-aqueous gelcasting are all uniform.The BSTM ceramics were prepared by non-aqueous gelcasting and dry pressing. The effects of different preparation methods on the phase compositions, microstructures and dielectric properties of the BSTM ceramics were investigated. The results demonstrate that there is no influence on the phase compositions whatever preparation method is adopted. Compared with dry pressing, the microstructures of the BSTM ceramics prepared by non-aqueous gelcasting are more uniform. Moreover, adopting non-aqueous gelcasting to prepare the BSTM ceramics could acquire the ones with more stable dielectric properties and could improve their dielectric properties in some extent.The BSTM ceramic powders were prepared by aqueous gelcasting-assisted solid-state method (AGASSM) and solid-state method (SSM). The effects of different ceramic powder preparation methods on the phase compositions and microstructures of the ceramic powders were investigated. Subsequently, adopting the dry pressing method to form samples, the effects of different ceramic powder preparation methods on the phase compositions, microstructures and dielectric properties of the BSTM ceramics were investigated. The results demonstrate that the BSTM ceramic powders prepared by AGASSM are more uniform with smaller (Dav=1.00μm) and more sphere-like particles than those prepared by SSM. The phase compositions of the prepared BSTM ceramic powders and the BSTM ceramics from the prepared ceramic powders are the same no matter what ceramic powder preparation method is adopted. Compared with SSM, the microstructures of the BSTM ceramics from ceramic powders prepared by AGASSM are more uniform. Furthermore, adopting AGASSM to prepare ceramic powders could not only improve the dielectric properties of the BSTM ceramics, but also decrease their sintering temperature.The BSTM ceramic powders were prepared by improved aqueous gelcasting-assisted solid-state method (IAGASSM), AGASSM and SSM. The effects of different ceramic powder preparation methods on the phase compositions and microstructures of the BSTM ceramic powders were investigated. Subsequently, adopting the dry pressing method to form samples, the phase compositions, microstructures and dielectric properties of the BSTM ceramics were investigated. The results demonstrate that the BSTM ceramic powders prepared by IAGASSM are the most uniform with the smallest particles (Dav=0.83μm) than those prepared by SSM and AGASSM. The phase compositions of the prepared BSTM ceramic powders and the BSTM ceramics from the prepared ceramic powders are the same no matter what ceramic powder preparation method is adopted. Compared with SSM and AGASSM, the microstructures of the BSTM ceramics from ceramic powders prepared by IAGASSM are the most uniform. Moreover, compared with SSM and AGASSM, adopting IAGASSM to prepare ceramic powders could not only improve the dielectric properties of the BSTM ceramics dramatically, but also decrease their sintering temperature.更多还原