云母微晶玻璃复合材料的研究进展

An Overview on Study of the Mica-based Glass-Ceramic Composites

云母微晶玻璃具有优异的可加工性、高热震性及良好的断裂韧性等多种优异性能,尤其是加工性能使其展现了良好的工程应用前景,引起人们广泛的兴趣。但层片状云母晶体的析出会使微晶玻璃强度有所下降,因此如何提高云母微晶玻璃的强度是多年来人们研究的重点。目前,用于提高云母微晶玻璃强度的方法可归纳为四种:(1)通过改变云母晶体层间结合离子的种类,提高云母晶体间的结合力;(2)通过调整基础玻璃组成和热处理制度裁剪显微组织,改善材料的强度;(3)通过热压等工艺实现定向析晶;(4)通过复合化设计形成复合材料,提高云母微晶玻璃的综合性能。其中云母微晶玻璃的复合化设计因具有复合相种类选择范围宽、添量可控、性能改善效果显著等优势而得到较大的发展。云母微晶玻璃复合材料的复合相以颗粒和纤维两大类为主。颗粒复合相包括惰性颗粒、非活性颗粒及活性颗粒。其中惰性颗粒是指颗粒本身不发生相变,与玻璃基体亦不发生反应的颗粒;非活性颗粒是指颗粒自身不发生相变,但颗粒成分之间可以发生反应的颗粒;活性颗粒可通过自身或与基体玻璃发生反应形成增强相。颗粒可添加到基础玻璃中,亦可添加到热处理前的母体玻璃中,通过改变微晶玻璃复合材料的组成,或改变云母基玻璃的析晶过程,或通过反应改变云母玻璃的析晶规律,进而影响材料的烧结。在此类云母微晶玻璃中,颗粒的种类和析出是影响云母微晶玻璃最终性能的关键。颗粒的选择及具有特殊功能的复合微晶玻璃材料的开发是未来研究的主要方向。纤维复合相主要以外加方式掺入,可有效改善云母微晶玻璃复合材料的韧性特征。有报道将碳纤维、SiO2/Al2O3纤维、AlN纤维等用于云母微晶玻璃复合材料的制备。在纤维云母微晶玻璃复合材料中,纤维与玻璃基体的界面结合问题是获得高性能复合材料的关键。本文综述了云母微晶玻璃复合材料的研究进展,介绍了云母微晶玻璃复合化的种类、制备及性能,着重评述了复合相在云母微晶玻璃中的作用及特征,提出了云母微晶玻璃基复合材料的发展趋势。

Mica-based glass-ceramics (MGCs) have gained extensive interests due to some interesting features of good machinability, high thermal shock resistance and fracture toughness etc., especially the machinability, exhibiting a variety of engineering applications. However, the MGCs show low strength because of the weak bonds between the layer structures of mica crystals. Therefore, it has always been one of the key points to increasing the strength in investigation of MGCs for many years. Up to now, there have been many methods to increase the strength of MGCs, in which, the strength could be increased by:(i) increasing the bonding force between the interlayers of mica structure by introducing the varieties of ions;(ii) tailoring the microstructure by adjusting the composition of base glasses and thermal treatments;(iii) the preferential crystallization by extruding or hot pressing processes, and (iv) fabricating the composites by adding or precipitating reinforced second phases. Among them, the MGC composites have been made obvious advances because of the wide choices of the reinforced phases, the controlled adding amounts and the improved excellent properties. The reinforced phases in MGC composites mainly include two types: particle and fiber. The particle phases compose inert particles that they are inert, there are not phase transition of themselves and would not react with components of parent glasses in the fabricating processes of MGC composites, un-active particles that they could not take place phase transition of themselves but might react with components of parent glasses, and active particles that they could react of themselves or with components of parent glasses. Those particles were introduced into composites by adding into base glasses or parent glasses before the thermal treatment. The formation of particle reinforced phases could influence the sintering processes of MGC composites by changing the components of composites or compositions of the parent glasses, or altering the crystallizing cha- racteristics owing to the reaction between particles and glasses. In particle-reinforced MGC composites, the types of particles and the precipitation of particles are two significant factors that influence the final properties of MGC composites. The choices of reinforced particles and MGC compo- sites with special functions will be main aspects to be explored. The fibers were usually introduced into composites by mixing with grains of the parent glasses before thermal treatment. The addition of the fibers were beneficial to improve the toughness strength of MGC materials. Nowadays, carbon fiber, SiO2/Al2O3 fiber and AlN fiber have been reported to be used for the fabrication of MGC composites. In fiber-reinforced MGC composites, the interfaces bonding between fiber and the parent glasses is a key factor, which affects the properties of MGC composites. In this paper, the development of MGC composites is reviewed. The varieties, preparation and properties of the MGC composites are summarized, in which, the effects and characteristics of the reinforced phases are emphasisly discussed. Also the development trends of MGC compo- sites are referred.