碳化硅陶瓷烧结助剂的作用机制与研究进展

Sintering Aids for Silicon Carbide Ceramics:Action Mechanisms and Research Progress

碳化硅(SiC)陶瓷由于其优异的高温强度、抗氧化性和化学稳定性,在石油化工、航空航天和热交换器等众多领域有广泛的用途。此外,SiC及其复合材料被认为是先进裂变反应堆和未来聚变反应堆的重要结构材料。由于Si-C键的高共价键合性和低自扩散性,纯SiC的烧结极为困难,只能通过高温高压的方式进行致密化。添加烧结助剂对促进SiC的致密化、缓和烧结条件至关重要。本文阐述了烧结助剂存在条件下碳化硅陶瓷致密化的热力学条件,总结了不同烧结机制下烧结助剂的作用机理。从助剂种类的角度综述了目前碳化硅陶瓷烧结领域的常用助剂体系及其研究进展,并展望了碳化硅致密化研究的发展方向。

Silicon carbide(SiC)ceramics are widely used in petrochemical,aerospace and heat exchangers owing to its excellent properties,such as high strength,high hardness and excellent resistance to oxidation,corrosion and thermal shock.In addition,SiC is also considered to be a structural component of future fission and fusion reactors because of its low activation under neutron irradiation conditions.However,pure dense SiC ceramics can only be obtained by sintering at high temperature with high pressure due to the high covalent bonding of Si-C bonds and low self-diffusion.In order to promote the densification of SiC and to alleviate the sintering conditions,the addition of sintering aids is crucial.In this paper,the thermodynamic conditions by adding sintering aids are discussed and the mechanisms of sintering aids to promoting SiC densification under different sintering conditions are summarized.The classification and the research progress of sintering aids for SiC ceramics in recent years are introduced.Future prospects of the research and development trend of the densification SiC ceramics are proposed.