Galvanic process for Cu-infiltration of W fibre-reinforced heat sinks

A challenging aspect in view of the realization of a future magnetic confinement fusion reactor is the design and manufacture of highly loaded divertor target plasma-facing components (PFCs) which have to sustain intense particle, heat and neutron fluxes. In this context, tungsten-copper (W-Cu) composites are currently being investigated as potentially advanced heat sink materials for PFCs. The development and manufacture of W-Cu composite pipes, which are bonded to tungsten monoblocks, poses new challenges in terms of manufacturing and accuracy.A new approach is proposed to produce the W-Cu composite pipe. The proposed alternative is to directly infiltrate tungsten fibers with galvanic copper instead of by copper infiltration in an furnace. The paper presents the status of the development to better assess the impact of various parameters affecting the galvanic process. Different braid thicknesses (3 and 6 layers) and their orientation (70° and 80°) have been tested. The effects of the electrolytic bath circulation, the variation in the braid material (porosities), and the electrolytic exchange by using pulsating direct current on the diffusion in the braid have been investigated. The influence of the passivation mode has also been carefully analyzed because in the case of a strong passivation copper only grows too quickly outwards from the core and not onto the tungsten braid.