PASSIVITY OF IRON AND NICKEL
Abstract
Electrical behavior of passive iron: The subpassive region is defined as that between -0.2 and +0.1 v where the current drops from 45 to 3 microamps. A curve shows the dependence of the logarithm of steady-state current on steadystate voltage in the region; the data were taken at 23 C in 2N H2SO4. Investigation of anodic red ction and concentration effects do not substantiate the claim of Sukhotin (J. Phys. Chem. (USSR) 32:1632, 1958) that a second plateau exists for an open-circuit break at low concentrations; the conclusion is that his second plateau occurred because the acetate buffer acted as a complexing agent. Passivation of nickel: A preliminary study in 2N H2SO4 indicates that the electrical behavior for passive Ni is more complicated than that for Fe. With a Ni electrode in solution the open-circuit potential is -0. 74 v. With the circuit closed and the potential 0.5 ma flows which remains constant for 1 or 2 min and then starts to increase. The increase accelerates with time until a maximum of 66 ma is reached in about 10 min. With the current above 1 ma, etching becomes visible as pitting, the pits growing in diameter and having a direct effect on the current. Some resistive layer was being removed as the current increased. The Ni system could be cycled, passivated readily, and recleaned.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 15, 1962
- Accession Number
- AD0278213
Entities
People
- J. A. Gardner Jr.
- James H. Bartlett
- L. D. Ferguson
- W. P. Perkins
Organizations
- University of Illinois Urbana–Champaign