3D-SiO_(2)-fiber中间层对SiC与Nb真空钎焊的影响

Effect of 3D-SiO_(2)-fiber interlayer on SiC and Nb vacuum brazing

缓解异种材料钎焊接头残余应力过程中,针对颗粒增强相添加量少、团聚等问题,引入一种新型三维SiO_(2)短纤维编织,呈疏松、多孔结构的复合材料中间层(3D-SiO_(2)-fiber)辅助SiC陶瓷与Nb钎焊连接。采用SEM,XRD和电子万能试验机等对活性钎料在3D-SiO_(2)-fiber中间层表面润湿性、接头微观组织和力学性能进行表征与分析。结果表明,当Ti元素含量从4.5%增加到6.0%,AgCu-Ti活性钎料在3D-SiO_(2)-fiber中间层表面润湿角从90°降低到3°,润湿性得到显著改善,且AgCu-Ti活性钎料浸入3D-SiO_(2)-fiber中间层深度不断增加;随着钎焊温度的提高(950~980℃)及保温时间(10~25 min)的延长,SiO_(2)短纤维与AgCu-6.0Ti活性钎料反应逐渐充分。该方法不仅保证SiO_(2)短纤维能够大量添加到合金钎料中,而且形成Cu 3 Si,TiSi,α-Ti及Ti 2 Cu颗粒相弥散分布于焊缝中,从而有效缓解钎焊接头残余应力,提高接头力学性能,实现陶瓷与金属复合构件的可靠连接。

In order to solve the problems such as the less addition and agglomeration of enhanced particles,a new composite interlayer was introduced to assist in brazing between SiC and Nb.The composite interlayer was braided by SiO_(2)-fiber in three dimension with loose and porous structure(3D-SiO_(2)-fiber).The wettability of 3D-SiO_(2)-fiber,microstructure and mechanical property of the joints were analyzed by SEM,XRD and electronic universal testing machine.The results show that,when the content of Ti increased from 4.5%to 6.0%,the wetting angle of AgCu-Ti active filler metal on the surface of 3D-SiO_(2)-fiber interlayer decreased from 90°to 3°.The wettability was significantly improved.Moreover,the immersion depth of AgCu-Ti active filler metal in 3D-SiO_(2)-fiber interlayer increased continuously.With the increase of brazing temperature(950~980℃)and holding time(10~25 min),the reaction between 3D-SiO_(2)-fiber and AgCu-6.0Ti active filler metal was gradually full.This method not only ensured that 3D-SiO_(2)-fiber was able to be added to the filler metal in a large amount,but also Cu 3 Si,TiSi,α-Ti and Ti 2 Cu particles dispersed in the joint.So,the residual stress was relieved and the shear strength of joint was improved.Then the reliable joint between ceramic and metal was realized.