Evidence of chemical passivity in amorphous Ni-20P alloy

Journal Article · Thu Jan 01 04:00:00 EST 1987 · J. Electrochem. Soc.; (United States)

DOI:https://doi.org/10.1149/1.2100392· OSTI ID:6607265

Diegle, R B; Clayton, C R; Lu, Y; Sorensen, N R

The authors observed that amorphous Ni-20P (atom percent) exhibits chemical passivity in 0.2N HCl. No distinct mechanical barrier to diffusion, such as an oxide film, is present. One characteristic of this chemical passivation process is that the absence of a barrier film would be expected to exclude the possibility of pitting, which occurs due to localized breakdown of passive films. The electrochemical studies revealed breakdown of the passive state (transpassivity) at approximately 0.2V, but with no accompanying pitting. Ni-20P amorphous alloy polarized in 0.2N HCl passivates at potentials between about -0.3 and 0.2V (SCE), beyond which transpassive dissolution occurs. In contrast, pure Ni does not show stable passivity and pits at potentials above the E/sub oc/ of -0.55V (SCE). The passive behavior if Ni-20P was verified in potentio-static experiments, which showed continuous decay of current for times beyond 10/sup 4/s and to current densities below 10/sup -6/ A/cm/sup 2/; at transpassive potentials, it dissolved at a nearly constant current density.

• Research Organization: Sandia National Labs., Albuquerque, NM
• OSTI ID: 6607265
• Journal Information: J. Electrochem. Soc.; (United States), Journal Name: J. Electrochem. Soc.; (United States) Vol. 134:1; ISSN JESOA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360105 -- Metals & Alloys-- Corrosion & Erosion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
ALLOYS
AMORPHOUS STATE
ANODIZATION
CHEMICAL COATING
CHEMICAL REACTIONS
CORROSION
CORROSION PROTECTION
CORROSIVE EFFECTS
DEPOSITION
ELECTROCHEMICAL COATING
ELECTROCHEMICAL CORROSION
ELECTROLYSIS
ELECTRON SPECTROSCOPY
ELEMENTS
HYDROCHLORIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
LYSIS
NICKEL ALLOYS
NONMETALS
OXIDATION
PASSIVITY
PHOSPHORUS
POLARIZATION
POTENTIOMETRY
QUANTITY RATIO
SPECTROSCOPY
SURFACE COATING
TITRATION