Invar合金与Si_3N_4陶瓷钎焊接头界面组织和性能研究

采用Ag Cu Ti活性钎料对Invar合金和Si3N4陶瓷进行钎焊连接,研究了接头界面组织及其形成机制,分析了钎焊工艺参数对接头界面结构和性能的影响。结果表明,钎焊过程中液态钎料中的活性元素Ti与Si3N4陶瓷发生反应,在陶瓷界面形成致密的Ti N和Ti5Si3反应层;同时,Invar合金向液态钎料中溶解,与活性元素Ti反应生成脆性的Fe2Ti和Ni3Ti化合物。钎焊温度和保温时间影响Si3N4陶瓷界面反应层的厚度以及接头中Fe2Ti和Ni3Ti脆性化合物的形成量和分布,这两方面共同决定着接头的抗剪强度。当钎焊温度为870℃,保温15 min时,接头的平均抗剪强度最大值达到92.8 MPa,此时接头的断裂形式呈现沿Si3N4陶瓷基体和界面反应层的复合断裂模式。

Microstructure and Mechanical Properties of Invar Alloy

Invar alloy and Si3N4 ceramic were brazed with AgCuTi active filler metal and the interfacial structure as well as the forming mechanism of the joint was studied. The effect of brazing parameters on the microstructure and mechanical properties of Invar/Si3N4 joints was investigated. The results show that TiN and Ti5Si3 layers were formed adjacent to Si3N4 ceramic due to the reaction between active Ti element and ceramic substrate. Meanwhile, Invar alloy dissolved into the liquid filler and reacted with Ti to form Fe2Ti and Ni3Ti compounds. The thickness of the reaction layer at Si3N4 ceramic and the formation of Fe2Ti-Ni3Ti brittle compounds were influenced by brazing temperature and holding time. When Invar alloy and Si3N4 ceramic were brazed at 870 oC for 15 min, the maximum shear strength of the joint reached 92.8 MPa. The crack primarily propagated at Si3N4 substrate and partially along the reaction layer.