对分别在空气气氛中使用100炉和在氮气气氛中使用5炉后（每炉均设定为1500℃保温3 h）的国产MoSi2发热元件进行了XRD、SEM和EDS分析，并探讨了其损毁机制。结果表明：1）国产MoSi2发热元件未变层气孔较多，腐蚀性气体易通过气孔与MoSi2反应造成损毁，少量的杂质相也可加速损毁；2）MoSi2发热元件在空气气氛中损毁的原因在于SiO2玻璃相以SiO气体挥发致使电阻不均，局部过热；3）氮气气氛中不能形成保护性玻璃膜，N2和少量CO与MoSi2反应生成Mo5 Si3、Mo3 Si、Mo、Mo2 C和Si3 N4，使其变质损毁。
Home-made MoSi2 heating elements were used at 1 500 ℃ for 3 h in air for 100 heats and N2 at-mosphere for 5 heats,respectively.They were analyzed by XRD,SEM and EDS,and their failure mecha-nisms were discussed.The results show that:(1 )there are many pores in the original part,which provide channels for the corrosive gas leading to failure,and a little impurities in the heating elements promote the failure as well;(2)failure of MoSi2 heating elements in air is attributed to SiO gas volatilization from SiO2 glass phase on the surface leading to uneven resistance and local overheat;(3)a protective film cannot form in N2 atmosphere because N2 and a few CO react with MoSi2 forming Mo5 Si3 ,Mo3 Si,Mo,Mo2 C and Si3 N4 leading to the deterioration damage.
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