Corrosion of electrolytic tough pitch copper and 70-30 brass in 5 percent NH4OH was effectively inhibited by 1000 ppm (NH4)2CrO4. In 25 percent NH4OH, the same (NH4)8CrO4 concentration effectively inhibited corrosion of 70-30 brass, but for comparable protection of copper, 20,000 ppm (NH4)2CrO4 were required.

Addition of (NH4)2CrO4 to 5 percent and 25 percent NH4OH decreased the time required to crack stressed 70-30 brass. Stressed electrolytic tough pitch copper did not crack in any of the test solutions.

Subject
Ions, Inhibitor performance, Dissolution, Transgranular stress corrosion cracking, Ammonia, Ion concentrations, U bends, Film formation, Color, Pitting, Copper, Brass, Stress corrosion cracking
© 1966 National Association of Corrosion Engineers
1966
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