The effect of active elements on the microstructure and properties of graphite and copper-brazed joints

• Published in: Radiation detection technology and methods 2024-12, Vol.8 (4), p.1619-1625
• Main Authors: Yu, Jiebing, Kang, Ling, Chen, Jiaxin, Zhang, Xiaofang, Shen, Xu, Wang, Guangyuan, Yu, Yongji, Liu, Lei
• Format: Article
• Language: English
• Subjects: Beam Physics; Hadrons; Heavy Ions; Nuclear Energy; Nuclear Physics; Original Paper; Particle Acceleration and Detection; Physics; Physics and Astronomy
• ISSN: 2509-9930; 2509-9949
• DOI: 10.1007/s41605-024-00484-7

Purpose To obtain better properties of joints of graphite/Cu brazing, brazing of graphite to oxygen-free copper with different coating has been employed. Methods Graphite is brazed to copper with surface coatings containing Cr, Ni or no element at 860 °C for 10 min. Results The shear strength of all joints exceeds 20 MPa. In addition to the interaction between the Ti element in the filler and the C element leading to the formation of TiC, the coating materials Cr and Ni also form Cr 7 C 3 and Ni 3 C, respectively. Compared to the Cr-coated and no-coated brazed samples, the filler is distributed more evenly in the Ni-plated brazed sample. TEM diffraction patterns have been utilized to calibrate the granular metal phase forming at the brazing filler metal boundary, revealing its composition Ti (Cu, Ni) 2 . The thermal conductivity of the brazed samples has been tested at different temperatures; the Cr-coated samples show significantly lower thermal conductivity than the uncoated samples. Conversely, the thermal conductivity of the Ni-coated samples is significantly higher than that of the uncoated samples. Conclusion Graphite and copper with different coatings can be successfully joined by using AgCuTi at 860 °C for 10 min. The graphite/Cu joint with Ni coating achieves better thermal conductivity with a more even distribution of the filler.