Analysis of hydrogen thermal desorption behavior of Ni-Ti superelastic alloy hydrogen-charged by cathodic charging and immersion testing

Abstract

We investigated differences in the hydrogen thermal desorption mechanism for Ni-Ti superelastic alloys following hydrogen charging by cathodic charging in a 0.9% NaCl aqueous solution and by immersion testing in a 0.2% APF aqueous solution. For the immersed specimen, the presence of corrosion products on the surface resulted in an upward shift of the hydrogen desorption peak by approximately 100 °C. When the total amount of desorbed hydrogen was almost the same for both specimens, a higher fraction was desorbed at temperatures below 200 °C for the cathodically charged specimen. Furthermore, a larger amount of hydride was formed for the cathodically charged specimen. These results indicate that the hydrogen thermal desorption mechanism depends on the presence of corrosion products on the surface and the amount of hydride formed.