为了获得满足一定气密性和强度要求的陶瓷-金属封接接头，本文采用Ag-Cu-Ti钎料作为连接材料，在真空环境下钎焊高纯氧化铝陶瓷和金属铌，研究了连接工艺（钎焊温度和保温时间）和钎料组成对接头组织、界面反应和接头性能的影响，分析了相关因素影响的原因；并且获得了合适的封接工艺条件，实现了高纯氧化铝与铌的气密性封接。研究了Ag-Cu-Ti钎料连接氧化铝陶瓷与铌时的接头组织和界面反应。接头主要由Al2O3/反应层/钎缝/Nb(Cu，Ti)/Nb组成；反应层中的元素主要为Ti、Cu、O、Al，反应产物主要为Ti的氧化物（Ti2O，TiO）和Cu3Ti3O(Al溶在其中)。钎料中的含Ti量、钎焊温度以及保温时间对接头组织中反应层的影响比较明显。合适的含Ti量、钎焊温度和保温时间下，有利于形成连续、致密的反应层；钎焊温度过高或保温时间过长时则使反应层连续性和致密性变差。Ag-Cu-Ti钎料在复合型和合金型两种使用型式下接头强度相差不大。钎料中含Ti量为1wt%和2wt%时，接头强度也相差不大；含Ti量增加到3wt%后，接头强度显著下降。钎料为AgCu1Ti时，当钎焊温度为850℃，保温时间为60min时接头剪切强度最高，达到119MPa。断裂多发生在近界面的陶瓷基体和反应层中。封接实验结果表明：封接温度对接头气密性的影响明显，封接时需合理选择；保证一定的封接压力有利于提高接头气密性。钎料使用AgCu3Ti，封接温度为850~875℃，保温时间为20min，一定钎焊压力下，可实现金属Nb（Nb引针，Nb盘）与高纯氧化铝的气密性封接，接头漏气率可达到10-12Pa•m3/s以下。实际构件上Nb引针的气密性封接结果显示，接头漏气率<5×10-11Pa•m3/s的接头比例可达97%。

To obtain hermetic joint of ceramic with metal, an active filler metal of Ag-Cu-Ti alloy was used to braze high purity alumina to niobium in the vacuum. The effects of filler metals and brazing conditions on joint microstructures, interfacial reactions and mechanical properties were studied, and the influence factors were discussed. Leak-tight joints were successfully made under proper conditions. Microstructures and interfacial reactions of the joints obtained were studied. The results show that the joints are composed of Al2O3 substrate/reaction layer/brazing seam/Nb (Cu, Ag)/Nb substrate. Elements of the interfacial reaction layer are mainly Ti, O, Cu and Al, corresponding the reaction products Cu3Ti3O (Al dissolves in it) and oxides of Ti (mainly Ti2O and TiO). The Ti-content in the filler metal, brazing temperature and holding time affect the reaction layer remarkably. Appropriate Ti-content in the filler metal, brazing temperature and holding time are in favor of forming continuous and compact reaction layers, which would become incompact when them are too much , too high and too long.The joint strength changes slightly when the Ti-content in the filler metal is 1wt% and 2wt%, and decreases significantly when it reaches 3%.The maximum shear strength of joints reaches 119MPa at 850℃ for 60min with the Ti-content 1wt%. Joint fractures were mostly occurred in the ceramic and the reaction layer. The results of experiments on sealing metal to ceramic show that the temperature for sealing carefully controlled and some pressure applied are helpful to obtain leak-tight joints. The conditions to obtain leak-tight joints are: temperature should be at 850~875℃, holding time is 20min ,using AgCu3Ti filler metal.The leak rate could be lower than 10-12Pa•m3/s。