Some Unusual Effects of Hydrogen in Corrosion Reactions

Abstract

Consideration of corrosion in the presence of water has led to the postulation of damage by hydrogen produced in the reaction. For cases where the metal surface is covered with a protective layer, it is considered that some hydrogen ions diffuse through the layer and form hydrogen atoms beneath it. The consequence of the production of hydrogen in this location is to decrease corrosion resistance. Three types of harmful effects are illustrated.

The Effect of Surface Preparation on Oxide Films on Cr and Fe-Cr Alloys

“…The significance of these observations has not been determined. It appears that both electrons and protons act as current carriers through the film (9). Which predominates, i.e., whether bubbles or blisters form, may depend on hydrogen overvoltage, electrode potential, oxide defect structure, film thickness, and some undefined property of the surface affecting the catalytic step in the hydrogen discharge reaction.…”

Reactions of plutonium dioxide with water and oxygen-hydrogen mixtures: Mechanisms for corrosion of uranium and plutonium

“…Reaction of OH-at the oxide-metal interface produces UOZand H+,a species that diffuses back to the gas-oxide interface, reacts with electrons, and associates to form Hr Linear kinetics are interpreted as implying that "oxidation is independent of oxide thickness." Similar mechanisms involving diffusion ofOH [31] and both OK and& [32] are also proposed for oxidation in moist air.…”

Formation and Degradation of Oxide Films on Beryllium

“…Поскольку растворимость водорода в бериллии очень мала, протоны, по-видимому, взаимодействуют в плёнке с электронами, об-разуя водород. Повышенное содержание водорода в оксидных плёнках в присутствии паров воды было обнаружено экспериментально масс-спектрометрическим методом [14,46]. Содержание водорода при окислении возрастает с 0,0045% (в исходном бериллии) до 0,03% (после окисления в смеси СО 2 + Н 2 О).…”

“…Согласно работе [46] для разрыва оксидной плёнки достаточно небольшого количества водорода в ней. Уменьшение толщины плёнки, при котором наступает её разрушение, с увеличением температуры объясняется ростом скорости диффузии протонов и более быстрым достижением критической концен-трации водорода.…”