Susceptibility to Stress Corrosion Cracking of Pure Copper in NaNO2 Solutions.

Abstract

The stress corrosion cracking (SCC) of pure copper poly-and single crystals in NaNO2 solutions was investigated potentiostatically by the slow strain rate technique. The susceptibility to SCC has a maximum in 1kmol・m-3 NaNO2 solution of 7.3-7.5 pH, at the strain rate below 1.67×10-5s-1. In this solution, a close correlation was found between the SCC and anodic polarization behavior of pure copper: The potential range for SCC occurrence was 0-100mV (SCE), nearly corresponding to that of passivity/transpassivity transition where the formation or rupture of black tarnish film (Cu2O) occurred. The fractographic results showed that many cracks nucleated from the specimen surfaces with frequent slip-steps, producing the tarnish film. The crack propagation was predominantly transgranular, along <110> direction on {110} plane. The evidence introduced here supports an anodic dissolution mechanism for the transgranular SCC of pure copper in NaNO2 solutions, including a tarnish rupture mechanism.

Stress corrosion cracking of copper in swollen bentonite simulating nuclear waste disposal environment

“…To the best of the authors' knowledge, this is the first report on tarnish crack-type SCC occurring on pure copper in swollen bentonite without NH 3 ; however, the tarnish rupture-type SCC of copper has been reported in various environments. [15,16] The surface oxide/sulfide film mainly consisted of Cu 2 O, which was relatively compact as compared with CuO. In contrast, the particulate deposits distributed randomly on the tensile specimen surface were porous and confirmed to be composed of CuO.…”

“…To the best of the authors' knowledge, this is the first report on tarnish crack‐type SCC occurring on pure copper in swollen bentonite without NH 3 ; however, the tarnish rupture‐type SCC of copper has been reported in various environments. [ 15,16 ]…”