Effect of Acidic Media During the Hydrothermal Leaching of NiTi Alloy

Abstract Nickel and titanium-based alloys are commonly used for engineering or medical applications. At the end of their lifetime NiTi alloys are recycled as additive materials. Separate recovery of metals present in NiTi alloy is possible via hydrometallurgical methods, however NiTi alloys are highly resistive towards corrosion. Different mineral acids (H2SO4, HCl, HNO3, H3PO4) have been investigated and the effect of presence of H2O2 in leaching medium has also been explored. Different leaching yields have been observed and correlation between them according to treatment conditions have been established. Microstructure and chemical properties of alloys were characterized by SEM, XRF and EDS techniques. Among mineral acids, H2SO4 and HCl illustrated the highest extraction efficiencies. Nevertheless addition of hydrogen peroxide decreased this efficiency severely. Throughout kinetics of dissolution were obtained through decreased leaching efficiency with addition of hydrogen peroxide.