Properties of Alumina/Chromia Scales in N2-Containing Low Oxygen Activity Environment Investigated by Experiment and Theory
Journal article, 2017

The FeCrAl alloy Kanthal APMT™ was exposed to N2–5%H2 at 900 °C. Trace oxygen in the gases supplied an oxygen activity which was sufficient to render alumina and chromia thermodynamically stable. The exposures revealed that the oxide scale was penetrated by nitrogen exclusively at chromia domains. Microscopic analyses of the oxide scale did not reveal micro-cracks that could serve as points-of-entry for nitrogen. Instead it is suggested that nitrogen is transported through a dense chromia layer. Density functional theory was employed to investigate decisive nitrogen surface chemistry and transport properties in chromia and alumina. The study was used to validate that the complex redox chemistry of Cr3+ as opposed to Al3+ is a sufficient discriminating factor between alumina and chromia, facilitating N2 dissociation and mobility of N in chromia.

Chromia

Transport properties of the oxide

Metastable phases

Alumina

Nitridation

Author

Christine Geers

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Vedad Babic

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Nooshin Mortazavi Seyedeh

Chalmers, Physics, Materials Microstructure

Mats Halvarsson

Chalmers, Physics, Materials Microstructure

Bo Jönsson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Lars-Gunnar Johansson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Itai Panas

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Jan-Erik Svensson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

Oxidation of Metals

0030-770X (ISSN) 1573-4889 (eISSN)

Vol. 87 3-4 321-332

Subject Categories

Inorganic Chemistry

Materials Chemistry

Other Materials Engineering

Theoretical Chemistry

Corrosion Engineering

Driving Forces

Sustainable development

Innovation and entrepreneurship

Areas of Advance

Nanoscience and Nanotechnology

Building Futures

Energy

Materials Science

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

Chalmers Materials Analysis Laboratory

DOI

10.1007/s11085-016-9703-3

More information

Latest update

11/1/2018