Development of a bonding technique for replantation of support leg on W-monoblock component

EAST upper divertor has been upgraded to ITER-like actively-cooled W/Cu components in May 2014. In the manufacture, assembling and disassembling of this W/Cu divertor, it was found that more than 10 support legs have dropped from the W/Cu-monoblock. In this work, the welding technique and drop reason of the support leg have been summarized and analyzed. To replant the dropped legs, some weld methods, including the middle-temperature brazing, electric resistance welding and 3D printing, have been performed and compared. Finally, the replantation technique based on 3D printing with laser beam has been developed and the nickel leg has successfully been printed on W block without the copper interface. In the development of the replantation technique, the microstructure and mechanical properties of the nickel leg have been researched to modify the printing technique. It is considered that this replantation technique also could be used in the ITER W divertor project.