Hydrogen absorption due to wear between Ni–Ti superelastic alloys in water

Abstract

Hydrogen absorption behavior has been investigated during wear between Ni–Ti superelastic alloys in purified water at room temperature by a hydrogen thermal desorption analysis. For the present wear test under a rotation speed of 100 rpm and an applied load of 2.0 N, the amounts of mass and thickness losses of a specimen increase without marked corrosion with increasing wear time. Even after 0.5 h, there is sufficient hydrogen absorption (approximately 12 mass ppm) to be detected. The amount of desorbed hydrogen (absorbed hydrogen) increases with increasing wear time. The hydrogen desorption behavior of wear specimens is not necessarily the same as those of cathodically hydrogen-charged specimens and specimens that absorbed hydrogen in acid solutions, as reported previously. The residual martensite phase and hydride are observed after the wear test. The present results indicate that Ni–Ti superelastic alloy absorbs a substantial amount of hydrogen, which causes hydrogen embrittlement, during wear in water within a short time.