High Heat Flux Testing of Graded W-Steel Joining Concepts for the First Wall

The realization of the first wall (FW), which is composed a protective tungsten (W) armor covering structural steel material, critical challenge in development future fusion reactors. Due to different coefficients thermal expansion (CTE) W and steel, direct joining them results cyclic stress at their bonding seam during operation reactor. To address this issue, study benchmarks two concepts. concept uses an atmospheric plasma sprayed graded interlayer W/steel composites with varying content gradually change CTE. second spark sintered interlayer. Furthermore, order benchmark these concepts, directly bonded W-steel reference joint as well featuring vanadium were also tested. These joints tested under steady-state high heat flux loading, starting from 1 MW/m2 up 4.5 MW/m2, stepwise increments 0.5 MW/m2. At each level, 200 cycles performed. survived only until 1.5 while V 3