Co-Nb-Pd-Ni-V钎料真空钎焊Cf/SiC复合材料的接头组织与性能

Microstructure and strength of the Cf/SiC composite joint brazed with Co-Nb-Pd-Ni-V filler alloy

关键词:  碳纤维增强碳化硅  钎焊  接头组织  接头强度  界面反应

Key words:  C_f/SiC composite  brazing  microstructure  joint strength  interfacial reaction

摘要:

采用自行设计的Co-Nb-Pd-Ni-V高温活性钎料对碳纤维增强碳化硅（C_f/SiC）复合材料进行钎焊连接，钎焊温度为1 200 ~ 1 320 ℃，钎焊时间固定为10 min. 结果表明，钎料中的V和Nb元素同时发挥反应活性，与C_f/SiC复合材料发生界面反应，在陶瓷界面形成了VC和NbC双层界面反应层. 当钎焊参数为1 280 ℃/10 min，典型的接头组织为（VC/NbC）双界面反应层/（Co，Ni）₂Si + CoSi + NbC + Pd₂Si/（NbC/VC）双界面反应层. 在此参数下获得的接头性能最佳，其中室温三点弯曲强度为61.0 MPa，在900和1 000 ℃下测得的强度均高于其室温强度，分别为83.2和87.7 MPa. 接头中的NbC和Pd₂Si高熔点物相弥散分布在钎缝内部，大大提高了接头的高温性能.

Abstract:

The C_f/SiC composite joint was brazed with newly-designed Co-Nb-Pd-Ni-V filler alloy at the brazing temperature from 1 200℃ to 1 320℃, and the brazing time was fixed at 10 min. The results showed that elements V and Nb in filler alloy played active roles in the interfacial reactions during the brazing procedure, and two interfacial reaction layers VC and NbC were formed at the C_f/SiC surface. Under the brazing condition of 1 280℃/-10 min, the joint microstructure can be characterized as (VC/NbC) double layers/(Co, Ni)₂Si + CoSi + NbC + Pd₂Si/(NbC/VC) double layers. The optimum joint strength can be achieved brazed at 1 280℃ for 10 min, and the room-temperature bend strength was 61.0 MPa. Furthermore, the joint strength tested at 900 and 1 000℃ was even elevated to 83.2 and 87.7 MPa, respectively. The good high-temperature joint strength can be attributed to the formation of high-melting-point compounds, such as NbC and Pd₂Si.