Passivity Mechanisms in Stainless Steels: Mo-N Synergism.
Abstract
Increasing the N content of a commercial grade 18-8 Stainless steel from 0.04% to 0.24% N was found to raise the breakdown potential from 200 mV to 304 vV in deaerated 0.1M HCl (pH 1.2). In deaerated 0.5M H2SO4 + 0.5M NaCl (pH 0.4) the 0.04% N alloy pitted at 448 mV. The 0.24% N alloy exhibited breakdown at 448 mV, a pitting inhibition potential at 540 mV, and a final pitting potential at 640 mV. Variable angle XPS studies of the passive film formed on the 0.24% N alloy at 0 mV after 10 seconds and 1 hour provided evidence of the role of N and SO4 in the initial stages of repassivation. The N was found to exist in three forms, namely CrN (397.1 eV) at the metal-film interface, a complex of NH3 or NO (399.6 eV) distributed throughout the passive film, and an ammonium salt (401.5 eV) observed at the passive film-solution interface.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1986
- Accession Number
- ADA172293
Entities
People
- Clive R. Clayton
Organizations
- Stony Brook University