TiB_(2)-TiC-SiC复合陶瓷接触反应钎焊接头界面组织及力学性能

Interfacial microstructure and mechanical properties of TiB_(2)-TiC-SiC ceramics joints fabricated by contact reactive brazing technique

采用Ti-Ni中间层体系对TiB_(2)-TiC-SiC(TTS)复合陶瓷进行了钎焊连接,研究不同的钎料成分和保温时间对接头界面组织和力学性能的影响。结果表明:钎料成分变化会引起界面反应机制由Ti与TTS复合陶瓷反应为主的过程向Ni与TTS复合陶瓷反应为主的过程转变。采用Ti-24at%Ni钎料钎焊TTS复合陶瓷时,界面反应主要发生在Ti与TTS复合陶瓷之间,反应产物主要为Ti与TiB_(2)反应形成的TiB以及与SiC反应形成的TiC和Ti_(5)Si_(3)。采用Ti-83at%Ni钎料钎焊TTS复合陶瓷时,界面反应主要发生在Ni与TTS复合陶瓷之间,尤其是与SiC的反应,反应产物主要为Ni;Si和C。此外,保温时间显著影响TTS/Ti-24at%Ni/TTS接头的界面组织和力学性能。随着保温时间的延长,接头中连续的Ti_(2)Ni化合物消失,形成大量的TiB和Ti_(5)Si_(3)。与此同时,TTS复合陶瓷侧界面反应层逐渐增厚。在钎焊温度为1040℃,保温时间为30 min条件下,采用Ti-24at%Ni钎料钎焊TTS复合陶瓷获得的接头室温抗剪强度最大,达到168±10 MPa,高温(800℃)抗剪强度达到81±18 MPa。

Ti-Ni brazing alloy is successfully used to braze the TiB_(2)-TiC-SiC(TTS)composite ceramic.The influence of change in Ti-Ni brazing alloy composition and brazing time on the interface microstructure and mechanical properties of the joint is studied.The results show that the change of Ti-Ni brazing alloy composition caused the interface reaction to change from a process dominated by the reaction of Ti and TTS ceramic to a process dominated by the reaction of Ni and TTS ceramic.When TTS ceramic is brazed using Ti-24 at%Ni brazing alloy,the interface reaction mainly occurred in Ti and TTS ceramic,and the reaction products were TiB_(2),TiC and Ti_(5)Si_(3).When TTS ceramic is brazed using Ti-83 at%Ni brazing alloy,the interface reaction,especially the reaction with SiC,mainly occurred in Ni and TTS composite ceramics,and the reaction products are mainly Ni;Si and C.With an increase in the brazing temperature,the continuous Ti_(2)Ni layer in the brazing seam gradually disappeared,and is replaced by TiB and Ti_(5)Si_(3).In addition,the thickness of the reaction layer increased with the increase of the brazing temperature.The maximum shear strength of the joint achieved at room temperature was 168±10 MPa when the TTS ceramic joint was brazed using Ti-24 at%Ni brazing alloy at 1040℃for 30 min,whereas it was 81±18 MPa when the joint is tested at 800℃.