The inhibiting effect of hydrofluoric acid in fuming nitric acid on the liquid-phase corrosion of aluminum alloys and iron alloys is found to be dependent primarily on the formation of a tenacious insoluble fluoride compound of aluminum or iron, respectively, on the surface of the metal. This mechanism is discussed in relation to: (1) solubility data for several pertinent compounds, (2) analysis of passivating coating on metal samples, and (3) correlation of solubility data with extent of corrosion of metal. The role diffusion plays in the passivation process is discussed briefly. Most of the measurements were made using fuming nitric acid containing 14 wt percent NO2 and 3 wt percent H2O, acid of this composition being thermally very stable. 3.8.3

Subject
Acids, Chemical compounds, Coatings, Fluorides, Acid concentration, Aluminum, Solids, Iron, Solubility, Nitric acid, Solutions, Metals, Passivation
Copyright 1958 by the National Association of Corrosion Engineers.
1958
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