SiC与耐热钢在高温真空中的界面反应机制研究

Interfacial Reaction Mechanism of Silicon Carbide and Heat Resistant Steel in High-Temperature Vacuum

碳化硅陶瓷可用作镁冶炼还原钢罐的内衬。在真空和1 200℃条件下,通过扩散偶试验,对SiC与耐热钢的界面反应进行了系统研究。结果表明,在反应初期,界面反应的主要产物为金属硅化物和石墨,其中分布在界面的片状石墨阻碍了界面反应。由于界面上低熔点硅镍化合物的熔化,片状石墨在Ni的催化作用下转变为纤维状石墨,失去了对碳化硅的保护作用。界面反应由固-固反应转变为固-液反应,界面反应过程加快,加速了钢对碳化硅的侵蚀。与耐热钢相比,SiC与纯铁的界面反应速率明显降低,金属熔化所需温度也显著升高。减少耐热钢中的Ni含量,可以有效阻止耐热钢和SiC之间的反应。

Silicon carbide(SiC) ceramics can be used as inner lining of reduction tank for magnesium smelting.The interfacial reaction between SiC and heat resistant steel was systematically investigated by diffusion couple experiment under vacuum and 1 200 ℃.The results show that at the early stage of reaction,the main products of interfacial reaction are metal silicide and graphite,and the lamellar graphite distributing at the interface hinders the interfacial reaction.However,due to the melting of silicon-nickel compounds with low melting point at interface,the lamellar graphite is transformed into fibrous graphite under the catalysis of Ni,losing its protective effect on silicon carbide.In addition,the interface reaction changes from solid-solid reaction to solid-liquid reaction,and the interfacial reaction process is accelerated,which accelerates the corrosion of silicon carbide by steel.Compared with heat resistant steel,the interfacial reaction rate between SiC and pure iron is obviously decreased,and the temperature required for the reaction is obviously increased.Reducing Ni content in heat resistant steel can effectively prevent the reaction between heat resistant steel and SiC.