Electrochemistry and corrosion of beryllium in buffered and unbuffered chloride solutions

The electrochemical behavior of Be (99%) in buffered and unbuffered chlorid e solutions is reported. Anodic oxidation and hydrogen evolution partial cu rrents were delineated by measuring the total current density and the rate of evolution of hydrogen from the metal surface. The partial anodic current density is found to decrease with increasing voltage within the passive ra nge at low voltages, but it tends toward a constant value at high voltages. Beryllium is observed to undergo passivity breakdown in chloride solutions , with the dependencies of the breakdown voltage on chloride concentration and pH being in accordance with the predictions of the point defect model. The barrier layer on beryllium in contact with aqueous solutions is most li kely defective BeO, with the principal defects bring oxygen vacancies and/o r beryllium interstitials. However, the present data do not discount the po ssibility that the barrier layer is the hydride, BeHx (x less than or equal to 2). (C) 2000 The Electrochemical Society. S0013-4651(99)04-032-X. All r ights reserved.