耐候性鋼橋梁に生成した層状剥離さび層局所の放射光 XRD 解析

抄録

  The detail structure of heavy rust layers with large swelling and laminated layers formed on weathering steel bridges have been investigated by optical microscope and laboratory powder X-Ray diffraction (XRD) and synchrotron XRD in SPring-8. Some large gaps (inter-layer) and many linearly arrayed voids (LAV) were found along layers. The mass ratio of spinel-type iron oxide [mainly Magnetite (Fe₃O₄)] in average composition of the whole layer 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 mass ratio of β-FeOOH was higher. Thus we propose a multilayer model structure for these unique rust layers which are made of Spinel Poor, Rich and Poor unit cell structure (SPRaP-cell) compartmentalized by LAV.