Comparison of aqueous corrosion behavior of zirconium and zircaloy-4 implanted with molybdenum

Abstract

In order to study the effect of molybdenum ion implantation on the aqueous corrosion behavior of zirconium and zircaloy-4, specimens were implanted by molybdenum ions with a dose range from 1 × 10 16 to 5 × 10 17 ions/cm 2 at maximum 160 °C, using MEVVA source at an extracted voltage of 40 kV. Auger electron spectroscopy and X-ray photoemission spectroscopy were employed to investigate the distribution and the valence of oxygen, zirconium and molybdenum ions inside the oxide films before and after implantation. Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zirconium in a 1 N H 2SO 4 solution. Scanning electron microscopy was performed for the three-sweep potentiodynamic polarized samples. It was found that the aqueous corrosion resistance of zirconium implanted with molybdenum declined with the raising dose. The greater is the implantation dose, the bigger is the decline. And the natural corrosion potential of the implanted zirconium became more positive than as-received zirconium. While as for zircaloy-4, the corrosion resistance of samples implanted molybdenum ions will increase when the doses are less than 5 × 10 16 ions/cm 2. Finally, the mechanisms of the corrosion behavior of the molybdenum-implanted zirconium and zircaloy-4 are discussed.