磁性微晶玻璃连接锂铁氧体接头组织演变及磁性能模拟  

Microstructure Evolution of Magnetic Glass-ceramic Brazed Lithium Ferrite Joint and Simulation of Magnetic Properties

作　　者：陈倩倩 马典 林盼盼[1] 林铁松[1] 何鹏[1] CHEN Qianqian;MA Dian;LIN Panpan;LIN Tiesong;HE Peng(State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin 150001)

机构地区：[1]哈尔滨工业大学先进焊接与连接国家重点实验室,哈尔滨150001

出　　处：《机械工程学报》2022年第4期34-40,共7页Journal of Mechanical Engineering

基　　金：国家自然科学基金(51805112,51974101,51975150);装备预研领域基金(61409230512);黑龙江省自然科学基金(LH2020E037);山东省重大科技创新工程(2019JZZY010366)资助项目。

摘　　要：锂铁氧体的玻璃连接技术能够克服常规烧结法无法制备复杂结构微波铁氧体构件的困难,并且微晶玻璃能够在铁氧体接头中原位析出磁性微晶相,进而实现连接件结构-功能一体化。设计并制备LFBi5B、LFBi15B、LFBi25B微晶玻璃钎料用于连接锂铁氧体,研究微晶玻璃在锂铁氧体表面的润湿性,钎料成分和连接温度对接头微观组织的影响规律,及锂铁氧体接头中焊缝的磁性来源。结果表明,三种微晶玻璃在铁氧体表面均具有较好的润湿性,锂铁氧体接头中原位析出LiFeO;晶体;随着连接温度升高,部分析出晶溶解,生成少量钛酸铋晶须。第一性原理模拟结果表明,钎缝中析出的主晶相LiFeO;总磁矩不等于0,上下自旋能带不对称,态密度图呈现自旋劈裂状态,均证明LiFeO;晶体具有磁性,其磁性来源为Fe、O原子的p、d态电子交换作用。通过试验与理论相结合,采用微晶玻璃连接锂铁氧体实现了接头中LiFeO;磁性微晶相的原位形成,验证了LiFeO;晶体的磁性来源,为磁性接头结构功能一体化设计提供了新思路。The glass joining technology of lithium ferrite can overcome the difficulty that the conventional sintering method cannot manufacture microwave ferrite components with complex structures, and the glass-ceramic can precipitate the in-situ magnetic microcrystalline phase in the ferrite joint, thereby realizing the structure-function integration of connected components. The glass-ceramics(LFBi5B,LFBi15B,LFBi25B) are designed for the joining of ferrite. The wettability of glass-ceramic, the effect of glass-ceramic composition and bonding temperature are studied, as well as the source of magnetism in the joint seam. The results show that the three glass-ceramics perform favorable wettability on YIG substrate. LiFeO;crystals are precipitated in situ in the joint.Some of the precipitated crystals dissolve with the temperature increasing. A small amount of bismuth titanate whiskers are generated.The simulation via the first-principle indicates that the total magnetic moment of the crystal is not equal to 0, the upper and lower spin energy bands are asymmetric, and the state density diagram shows the spin-split state, which proves that the LiFeO;crystal owns magnetism. The magnetism results from the exchange of electrons in the p and d states of Fe and O atoms. This investigation combines experiment and theory, realizing the in-situ growth of magnetic LiFeO;microcrystals in YIG joint brazed by glass-ceramic,meanwhile verifying the magnetic source, which provides a new idea for the integrated design of structure and function of magnetic joints.

关 键 词：磁性微晶玻璃 铁氧体 微观组织 磁性能 第一性原理 

分 类 号：TG425[金属学及工艺—焊接]