二硅化钼发热体在氢气气氛中使用的侵蚀机制分析
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摘要
将二硅化钼发热体安装在氢气气氛电阻炉中,升温至1 350℃保温6 h后结束为1炉次,共使用5炉。然后截取使用后的二硅化钼发热体热端,用扫描电子显微镜研究其显微结构,用能谱分析仪进行区域元素分析,以剖析二硅化钼发热体在氢气气氛中使用的侵蚀机制。结果表明:在氢气气氛中使用时,二硅化钼发热体表面的保护膜首先被氢气破坏且不能再生,进而发热体中的硅酸盐结合剂也被氢气破坏并形成氢气进一步侵蚀的通道,加速了氢气与本体材料二硅化钼的反应。二硅化钼发热体由于侵蚀变细、结构疏松并剥落,电阻过大、温度过高而熔断,从而导致其在氢气气氛中的使用寿命大大降低。
A molybdenum disilicide( MoSi_2) heating element was equipped in an electric resistance furnace with hydrogen atmosphere. Heating the furnace to 1 350 ℃ and holding for 6 h is defined as one heat. After5 heats,the hot end of the used MoSi_2 heating element was cut and analyzed with SEM and EDS to investigate the erosion mechanism of MoSi_2 heating elements in hydrogen atmosphere. The results show that when serving in hydrogen atmosphere,the surface protective film of the MoSi_2 heating element is first destroyed by hydrogen and cannot regenerate; then the silicate binder of the heating element is also destroyed by hydrogen so the channels for hydrogen erosion form,accelerating the reaction between hydrogen and MoSi_2; due to erosion the heating element becomes thin and loose,and spalls,and due to the high electric resistance and high temperatures,the heat element fuses,which reduce the life of MoSi_2 heating elements in hydrogen atmosphere.
A molybdenum disilicide( MoSi_2) heating element was equipped in an electric resistance furnace with hydrogen atmosphere. Heating the furnace to 1 350 ℃ and holding for 6 h is defined as one heat. After5 heats,the hot end of the used MoSi_2 heating element was cut and analyzed with SEM and EDS to investigate the erosion mechanism of MoSi_2 heating elements in hydrogen atmosphere. The results show that when serving in hydrogen atmosphere,the surface protective film of the MoSi_2 heating element is first destroyed by hydrogen and cannot regenerate; then the silicate binder of the heating element is also destroyed by hydrogen so the channels for hydrogen erosion form,accelerating the reaction between hydrogen and MoSi_2; due to erosion the heating element becomes thin and loose,and spalls,and due to the high electric resistance and high temperatures,the heat element fuses,which reduce the life of MoSi_2 heating elements in hydrogen atmosphere.
引文
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