Vacuum Brazing and Heat Treatment of Cu-Cr-Zr Alloy

摘要

Two pairs of poloidal Limiters, one each on the outboard and the inboard sides of the plasma column, form part of the plasma facing components in SST-1. The limiters receive high heat and particle fluxes and hence the design of them involves actively cooled copper alloy heat sinks. The plasma facing surface temperature of the poloidal limiters may go up to 1000°C and the heat removal rate requirement is estimated to be around 1 MW/m~2. They are also subjected to large electro-magnetic forces due to disruptions and halo currents. Considering the above general aspects and the specific need of high thermal conductivity along with good mechanical strength, the copper-chromium-zirconium (CuCrZr) alloy has been chosen as heat sinks for limiters. This study addresses the mechanical strength and vacuum brazing of CuCrZr alloy with SS304L cooling tube. The UTS of CuCrZr alloy was found to reduce to about 40% of its initial value after subjecting the same to high temperature brazing cycles. Heat treatment and cold working techniques were tried as means to recover the lost strength.