MoSi2发热元件高温通电氧化成膜规律

研究了MoSi2发热元件在1400～1600℃，空气中氧化0．25～3 h的氧化成膜规律，采用SEM和EDS测试技术分析了MoSi2发热元件通电氧化以后氧化层的组织形貌和相组成，并对其氧化膜的生长规律和抗弯强度变化原因进行了探讨。结果表明：MoSi2发热元件氧化膜生长规律符合L＝0．43＋5．05′107exp（-28397．88T ）t1/2关系，氧化激活能为236 kJ/mol。抗弯强度随着氧化膜的致密和增厚而提高，在1600℃通电氧化3 h后，氧化膜生长了22．3μm，抗弯强度达到了273 MPa，比氧化前提高了51．67％。

ELECTROTHERMAL OXIDATION LAWS OF MoSi2 HEATING ELEMENT FILM

The oxidation kinetics of MoSi2 heating element including thickness of oxidized layer gain vs time and temperature have been studied in the condition of 1 400~1 600 ℃,0.15 ~3 h,in air atmosphere.The changes of substrate and oxidized surface layer of the composite were examined by means of SEM,X -ray diffraction.The growth law of oxidized surface layer and the reasons of bending strength changed has also been explored.The results show that the growth law of oxidized surface layer obeys formula L=0.43＋5.05′107exp（-28397.88 ）t1/2 ,and ac-T tivation energy is 236 kJ/mol.Because oxide film becomes more dense and the thickness of oxidized surface layer increases more,the bending strength of MoSi2 heating element can be improved.When MoSi2 heating element oxi-dized for 3 h at 1 600℃ ,the thickness of oxidized surface layer increases 22.3 μm,the bending strength of oxi-dized MoSi2 heating element reaches 273MPa and increases 51.67% than before oxidation.