Erosion–corrosion tests on ITER copper alloys in high temperature water circuit with incident heat flux

Abstract

To investigate the erosion–corrosion behavior of the Cu-alloys, i.e. CuCrZr and CuAl25-candidate materials for the manufacture of the diverter cooling channels for ITER, a test loop has been developed for testing erosion–corrosion behavior under high heat flux conditions. The heat loads on the test specimen surface amounts to 10 MW/m 2. Under adverse testing conditions in oxidizing water (5–10 ppm H 2O 2) at 100 °C, with a flow velocity of 10 m/s and intermittent heat loading, followed by cooling cycles under oxidizing conditions maintained, CuCrZr alloy has shown the formation of a thick surface oxide films (essentially cupric oxide, CuO). This surface layer seems loosely adhesive, and detachable by mechanical or thermal shocks, or by fluid flow velocity effects. Indicated with a rough morphology, surface attacks were somewhat observed in areas after the surface oxide layer spalled off. Present results suggest the necessity for, such as, strict hydrogen water chemistry (HWC), in order to limit the copper corrosion rate or at least the release of copper into the cooling water circuit.