Corrosion of AZ31 Mg alloy was systematically investigated by different experimental approaches in the presence and in the absence of NH4+. Remarkable reactivity of Mg/NH4+ system was manifested by copious evolution of hydrogen over a dark corrosion film, associated to active deprotonation of complex Mg hydrides, more likely bridged Mg2+(AlH4-)2Mg2+(H-)2 complexes covered by a skin of MgO. Metastability of hydride phases is favored in the presence of species that alter the equilibrium dissociation of water, such as NH4+ and SO42-. Chemical recombination of hydrogen atoms of oxidic Mg hydrides is proposed as the kinetically determinant process.

Corrosion of Mg alloy in the presence of ammonium ion : evidence of hydride sub-products / D. Buggio, M. Trueba, S.P. Trasatti. - In: CORROSION SCIENCE. - ISSN 0010-938X. - 104(2016), pp. 173-186. [10.1016/j.corsci.2015.12.008]

Corrosion of Mg alloy in the presence of ammonium ion : evidence of hydride sub-products

M. Trueba
;
S.P. Trasatti
Ultimo
2016

Abstract

Corrosion of AZ31 Mg alloy was systematically investigated by different experimental approaches in the presence and in the absence of NH4+. Remarkable reactivity of Mg/NH4+ system was manifested by copious evolution of hydrogen over a dark corrosion film, associated to active deprotonation of complex Mg hydrides, more likely bridged Mg2+(AlH4-)2Mg2+(H-)2 complexes covered by a skin of MgO. Metastability of hydride phases is favored in the presence of species that alter the equilibrium dissociation of water, such as NH4+ and SO42-. Chemical recombination of hydrogen atoms of oxidic Mg hydrides is proposed as the kinetically determinant process.
Magnesium; Hydrogen absorption; Negative difference effect
Settore ING-IND/23 - Chimica Fisica Applicata
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/450518
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