Kinetics and mechanism of high-temperature oxidation of dilute cobalt-chromium alloys

Journal Article · Thu Apr 01 04:00:00 EST 1982 · Oxid. Met.; (United States)

DOI:https://doi.org/10.1007/BF00738387· OSTI ID:6527002

Przybylski, K; Swagierczak, D

Kinetics of oxidation of Co-Cr alloys containing 0.4%-15% Cr was studied as a function of temperature (1273-1573 K) and oxygen pressure (4 X 10/sup 2/-10/sup 5/ Pa). The oxidation process was found to be approximately parabolic and faster than that for pure cobalt. The scales are double-layered and consist of a compact outer CoO layer and a porous inner layer containing CoO slightly doped by chromium and spinel CoCr/sub 2/O/sub 4/. The oxidation mechanism was investigated by means of platinum markers and the /sup 18/ O isotope. The scale on the alloys containing less than 1% Cr grows exclusively by outward diffusion of cobalt, while that on the alloys containing more chromiumwith a significant contribution of inward oxygen transport from atmosphere. This transport is not a lattice diffusion, but proceed presumably through microfissures resulting from the secondary process of perforating dissociation of the outer scale layer.

• Research Organization: Academy of Mining and Metallurgy, Krakow
• OSTI ID: 6527002
• Journal Information: Oxid. Met.; (United States), Journal Name: Oxid. Met.; (United States) Vol. 17; ISSN OXMEA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COBALT ALLOYS
CRYSTAL STRUCTURE
ELEMENTS
KINETICS
METALS
MICROSTRUCTURE
OXIDATION
PLATINUM
PLATINUM METALS
REACTION KINETICS
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE