Exploration of the applications of graphite/copper composites in accelerators

Purpose The purpose of the study was to prepare and evaluate the performance of graphite/copper composites in accelerators.
Methods A series of graphite/copper composites were prepared by powder metallurgy. Based on the relative density, bending strength, thermal conductivity, linear expansion coefficient, steady-state stability normalized index (SSNI), and electrical conductivity, the ratio of graphite/copper in the composites was optimized.
Results The type of graphite greatly influenced the properties of the resulting graphite/copper composites. Compared with flake graphite/copper, spherical graphite/copper had a higher bending strength, thermal conductivity coefficient, SSNI, and conductivity. Although the dopant did not react with graphite, it greatly impacted the properties of the graphite/copper composite. Increasing the graphite content after doping with Ti and Ni resulted in a higher thermal conductivity and SSNI compared with the undoped or mono-doped composites. The graphite content greatly influenced the thermal conductivity of the composite. When the graphite content did not exceed 40 vol%, the thermal conductivity of the graphite/copper composite changed only slightly with the temperature. When the graphite content exceeded 45 vol%, the thermal conductivity of the graphite/copper composite decreased with temperature.
Conclusion Among the prepared graphite/copper composites, titanium/nickel/spherical graphite/copper with a spherical graphite content of 50 vol% had the largest SSNI, which was higher than that of copper. Under specific conditions, it may be used as a substitute for copper in collimators or beam dumps. Different graphite/copper composites showed different coefficients of linear expansion, with a reasonable allocation of graphite and dopants. These composites may be used as transition layers in the brazing connection of large graphite and copper-based materials.