可伐合金气密封接的预氧化

可伐合金和硅硼硬玻璃是通过可伐合金表面的氧化物与玻璃互溶而紧密结合在一起的,所以可伐合金的预氧化是金属外壳制造的一个非常重要的工艺环节,是直接影响气密封接的一个重要因素。为实现气密封接,可伐合金预氧化需要得到的氧化物应是Fe_3O_4和FeO,而不希望得到Fe_2O_3。同时,氧化膜的厚度要控制在一定的范围内;氧化膜过薄则氧化物完全溶于玻璃,造成玻璃与金属基体表面的直接封接,使封接强度下降;氧化膜过厚则造成金属表面氧化物较粗糙疏松,封接件容易漏气。为达到上述两个目的,可以从可伐合金氧化的热力学和动力学出发,通过控制氧化气氛,氧化温度和时间来实现。

Preoxidation of Kovar Alloy for Hermetic Sealing

Hermetic sealing of kovar to borosilicate glass is achieved by oxide of kovar surface. Preoxidation of kovar alloy is a very important process in manufacturing metal packages and directly influences whether hermetic sealing can be made. Fe_3O_4 and FeO are preferred and Fe2O_3 is undesired on kovar surface in order to achieve hermetic sealing. At the same time, the thickness of oxide should be controlled in some range. If it is underoxidized, glass will touch with metal substrate directly and lead to poor sealing strength because oxide is resolved in glass completely. If it is overoxidized, seals will be prone to leak because oxide is rough and loose. Therefore, these can be realized by controlling atmosphere、temperature and time of oxidation based on thermodynamics and kinetics of kovar alloy.