Electrolytic hydrogen charging of Zr-2.5Nb alloy in molten NaOH-KOH eutectic mixture at low overpotential

The major contributions of this thesis include: first, it proved the effectiveness for the method of electrolytic charging Zr-2.5Nb alloy with hydrogen in moist NaOH-KOH melt at low overpotential; second, it employed a Hg/HgO RE in YSZ membrane and investigated its performance; last, it found an optimized voltage range for the potentiostatic charging process. The equilibrium potential of hydrogen evolution reaction in the melt is estimated to be slightly higher than -0.85V, measured by the Hg/HgO RE. The optimized voltage range is -0.85 V to - 0.875 V. Within this range, scattered hydride distribution in the internal metal bulk is observed, and hydrides precipitate at controllable rates, avoiding the intensive accumulation in a thin subsurface layer. The Hg/HgO RE provides a stable and reproducible OCP reading around - 0.785 V for nickel plated zirconium samples in the melt. The potential difference between the three Hg/HgO RE for this project is ±10 mV. (author)