Multi-modal plasma focused ion beam serial section tomography of an organic paint coating

• Published in: Ultramicroscopy Vol. 197; pp. 1 - 10
• Main Authors: Zhong, Xiangli, Burke, M. Grace, Withers, Philip J., Zhang, Xun, Zhou, Xiaorong, Burnett, Timothy L., Liu, Yanwen, Lyon, Stuart B., Gibbon, Simon R.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-02-2019
• Subjects: 3D EDX/3D EBSD; Analytical PFIB; Correlative tomography; Organic paint coating; Ultramicrotomy; Ultramicrotomy; Analytical PFIB; Organic paint coating; Correlative tomography; 3D EDX/3D EBSD
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2018.10.003

•Multi-modal tomographic analysis using analytical PFIB (3D EDX SI + 3D EBSD + 3D eSE) can be applied to organic coating.•A semi-automated block preparation procedure was introduced to eliminate labour intensive conventional lift-out process.•The faster milling rate of the Xe+ PFIB compared to that of the Ga+ FIB permits the analysis of larger sample volumes.•The volume, morphology and size of the pigments were quantified in 3D. Larger flakes provide better barrier effect.
Pigment distributions have a critical role in the corrosion protection properties of organic paint coatings, but they are difficult to image in 3D over statistically significant volumes and at sufficiently high spatial resolutions required for detailed analysis. Here we report, for the first time, large volume analytical serial sectioning tomography of an organic composite coating using a xenon Plasma Focused Ion Beam (PFIB) combined with secondary electron imaging, energy dispersive X-ray (EDX) spectrum imaging (SI) and electron backscattered diffraction (EBSD). Together these techniques provide a comprehensive quantitative description of the physical orientation and distribution of the pigments within a model marine ballast tank coating, as well as their crystallographic and elemental characterisation. Polymers and organic materials are challenging because of their propensity for ion beam damage and possible beam heating effects. Our novel, optimised block preparation technique permits automated data acquisition with minimal operator intervention, and can have significant applications for the structural and chemical characterisation of a wide range of organic materials. Our results revealed that the paint contained 7.5 vol% aluminium flakes and 25 vol% quartz particles. The aluminium flakes were oriented parallel to the substrate surface, which is beneficial in terms of the corrosion protection capability of the coating.