MECHANISM OF CORROSION OF METALS IN NARROW CRACKS AND CREVICES. IV. CORROSION OF ALUMINUM AND SOME OF ITS ALLOYS,
DEPARTMENT OF THE NAVY WASHINGTON D C
Pagination or Media Count:
The corrosion and electrochemical behavior of aluminum and some of its alloys in narrow cracks and in sodium chloride solutions was examined. It was established that the corrosion rate of the metal in a narrow crack was one order of magnitude greater than the corrosion rate of this metal when washed by an electrolyte. It was demonstrated that intensive corrosion of the test metals in cracks resulted from variation of the composition of the corrosive environment in the crack, as a function of the activity of the macrocells formed as a result of differences in the rate of supply of oxygen to the crack and to the metal washed by the electrolyte. The negative difference effect for aluminum in a narrow crack was examined. It was established that with anodic polarization the difference effect for the aluminum amounted to 40-47. It was demonstrated that such an unusual increase in the difference effect results from acidification of the electrolyte in crack due to hydrolysis of the products of anodic reaction.
- Physical Chemistry
- Properties of Metals and Alloys