A X-Ray Diffraction Analysis on Constituent Distribution of Heavy Rust Layer Formed on Weathering Steel Using Synchrotron Radiation

Abstract

A local structural analysis of heavy rust layers with large swelling and laminated layers formed on weathering steel bridges using synchrotron radiation X-ray diffraction (SR-XRD) in SPring-8 have been performed. The main constituent in average composition of the whole layer was spinel-type iron oxide [mainly Magnetite (Fe₃O₄)] and the mass ratio was 30-40 mass%. In contrast the mass ratio of spinel in its local parts, i.e. outer layer, inter-layer and inner layer position was not higher in common but the mass ratio of β-FeOOH was higher. Therefore it indicates that these heavy rust layers have been composed of many layers of spinel poor, rich and poor - cell (SPRaP-cell). Thus SR-XRD is useful for the analysis of the constituent distribution in the rust layer.