ANODIC PASSIVATION OF STAINLESS STEEL.
ROCK ISLAND ARSENAL ILL
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Cathodic activation, anodic and immersion passivation treatments on types 310, 321, 410 stainless steel panels, and M1 gas cylinders were investigated in 5 solutions of Na2SO4, Na2Cr2O7. Passivation in 20 HNO3 containing 2 Na2Cr2O7 was conducted as described in MIL-STD171A. A Sargent Recorder, Model MR, an automatic self-balancing potentiometer, was used to measure potentials with reference to a normal Calomel-cell and a salt bridge in contact with a stainless steel panel in an auxiliary vessel containing 0.001N NaC1. Potential vs. time measurements were plotted graphically to show the effects of the treatments on the stainless steels. Passivation treatments increased the positive potential activation increased the negative potential half-cell potential measurements showed a decay in panel potential vs. time in air exposure. Passivated panels in salt spray exposure afforded slightly better protection than the control panels. Passivated panels in outdoor exposure showed no appreciable difference between the types of stainless steels in the prevention of corrosion. Author