反应合成非氧化物陶瓷材料

Reactive Synthesis of Non-Oxide Ceramics

反应合成是陶瓷材料的重要制备工艺之一,在制备块体陶瓷、纤维增强复合材料基体、复合材料的陶瓷防护涂层等方面具有广泛的应用。本文简要介绍了作者多年来在反应合成复相陶瓷方面的研究结果,包括硼化钛体系、硼化锆体系、碳化物体系、氮化硼体系以及最近发展起来的高熵陶瓷体系。不同的反应体系包含有化学性质完全不同的反应物、化学反应中可能存在较大的放热现象、反应物存在分解后再反应等中间过程、产物中可能存在气相副产物等不同特征,后续致密化过程与前期反应过程的控制具有复杂多样的密切关系,所以深入研究前期反应过程和后期致密化及显微结构形成机理对反应合成具备特殊显微结构和性能的陶瓷材料具有重要的意义。高温化学反应不仅可以用于合成陶瓷材料,在采用非反应合成的常规工艺制备陶瓷材料特别是非氧化物陶瓷的过程中也普遍存在,了解这些化学反应进行的条件有利于设计合理的工艺制度,从而获得性能优越的材料。

Reactive synthesis is an important processing for the preparation of ceramic materials,including bulk ceramics,the matrix of fiber-reinforced ceramic matrix composites,as well as the protection coatings for ceramic matrix composites.In this paper,the research results on the reactive synthesis of particulate ceramic composites in the decades by the research group including titanium diboride-based systems,zirconium diboride-based systems,carbide-based systems,hexagonal boron nitride-based systems and the recently developed high-entropy ceramic systems are comprehensively introduced.The reactants for a special reactive synthesis system are much different,for example,metallic reactants or gaseous reactants.Some reactions will generate large heat.Some reactions will demonstrate complicated intermediate reactions including decomposition and then reaction.Some reactions will produce gaseous by-products.Accordingly,it is very important to investigate the reaction mechanisms for the preparation of ceramic materials with special microstructures and enhanced properties.High temperature chemical reactions not only can be used to in-situ synthesize ceramics,but also widely exist in the processing of ceramic materials especially non-oxide ceramics.Understanding the conditions under which how the reactions will take place are very helpful to design the processing parameters for the preparation of ceramic materials with improved properties.