SiO_2在SHS铝热-重力分离法制备陶瓷内衬复合钢管中的作用

采用自蔓延铝热-重力分离法,制备了陶瓷内衬复合钢管,并系统研究了SiO_2添加剂对SHS燃烧过程、陶瓷层相对密度与组织结构、复合钢管力学性能的影响。经研究发现,SiO_2在铝热燃烧过程中作为稀释剂存在,随着SiO_2添加量增多,燃烧温度与蔓延速率下降,并使分布于α-Al_2O_3枝晶晶界处的亚稳定相FeO·Al_2O_3增多;陶瓷相对密度与复合钢管抗压溃强度在SiO_2含量为2wt％时出现极大值(分别为92.5％与430MPa);陶瓷硬度、断裂韧性与复合钢管抗压剪强度随SiO_2含量增加而降低。

THE ROLES OF SiO_2 IN THE CERAMIC - LINED PIPES PRODUCED BY SHS GRANITATIONAL SEPARATION THERMIT METHOD

The ceramic - lined pipes have been produced by the gravitational separation -thermit method, and the effects of SiO2 additive on the combustion process, dentification, structure of ceramic layer and mechanical propertites of the pipes have been investigated. It is considered that SiO2 in thermit acts as the diluent during combustion process, causing combustion temperature and propagation rate to be reduced, and mestastable phase FeOAl2O3 distributed at dendritic grain boundary of a- Al2O3 to be increased. As SiO2 addtive is up to 2wt% , relative density of ceramic layers and the compressive strength of the pipes present the maximum values (up to 92.5% and 430MPa, respectively), and hardness, fracture ductility of ceramic layers and compressive shear strength of the pipes are reduced with increasing content of SiO2 additive