Quantitative µ-CT Analysis of Scale Topology Formed during Oxidation of High SiMo Cast Iron


High SiMo cast iron components in automotive exhaust systems are exposed to high-temperature oxidation over time. Quantitative analysis of formed oxide scale is therefore important for the assessment of a component durability. The brittle nature of multilayered scale and thermal stress limits capture of a true topology using traditional 2D destructive cut and polish methods. In this study, nondestructive high spatial-resolution 3D µCT analysis was performed on 2.90-mm-diameter oxidized specimens which permitted direct observation with 3.5 µm pixel resolution. The specimens were oxidized in three sequential time steps for a total 100 h at 700 °C and 800 °C in air and combustion gas atmospheres. A MATLAB-coded algorithm was used to quantify the topology, thickness variation in internal and external scale layers, and scale/metal interface unevenness. Scale topology was linked to oxidation temperature and gas atmosphere. A water vapor environment increases scale/metal interface unevenness and scale layer thickness irregularity which were related to an accelerated oxidation rate.


Materials Science and Engineering

Keywords and Phrases

Micro-CT; Morphology; Scale; SiMo Cast Iron

International Standard Serial Number (ISSN)

0030-770X; 1573-4889

Document Type

Article - Journal

Document Version


File Type





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Publication Date

01 Oct 2020