title: X-ray Computed Tomographic Investigation of the Porosity and Morphology of Plasma Electrolytic Oxidation Coatings.
abstract: Plasma electrolytic oxidation (PEO) is of increasing interest for the formation of ceramic coatings on metals for applications that require diverse coating properties, such as wear and corrosion resistance, low thermal conductivity, and biocompatibility. Porosity in the coatings can have an important impact on the coating performance. However, the quantification of the porosity in coatings can be difficult due to the wide range of pore sizes and the complexity of the coating morphology. In this work, a PEO coating formed on titanium is examined using high resolution X-ray computed tomography (X-ray CT). The observations are validated by comparisons of surface views and cross-sectional views of specific coating features obtained using X-ray CT and scanning electron microscopy. The X-ray CT technique is shown to be capable of resolving pores with volumes of at least 6 μm(3). Furthermore, the shapes of large pores are revealed and a correlation is demonstrated between the locations of the pores, nodules on the coating surface, and depressions in the titanium substrate. The locations and morphologies of the pores, which constitute 5.7% of the coating volume, indicate that they are generated by release of oxygen gas from the molten coating.
authors.affiliation: Henry Moseley X-ray Imaging Facility, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: Xun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Corrosion and Protection Group, School of Materials, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Aliasghari
authors.affiliation: Corrosion and Protection Group, School of Materials, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: Aneta
authors.initials: A
authors.lastname: Němcová
authors.affiliation: Henry Moseley X-ray Imaging Facility, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Burnett
authors.affiliation: Institute of Physics of Materials, Academy of Sciences of the Czech Republic , Žižkova 22, Brno 616 62, Czech Republic.
authors.forename: Ivo
authors.initials: I
authors.lastname: Kuběna
authors.affiliation: Institute of Physics of Materials, Central European Institute of Technology , Žižkova 22, Brno 616 62, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Šmíd
authors.affiliation: Corrosion and Protection Group, School of Materials, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: George E
authors.initials: GE
authors.lastname: Thompson
authors.affiliation: Corrosion and Protection Group, School of Materials, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: Peter
authors.initials: P
authors.lastname: Skeldon
authors.affiliation: Henry Moseley X-ray Imaging Facility, The University of Manchester , Manchester M13 9PL, U.K.|BP ICAM, The University of Manchester , Manchester M13 9PL, U.K.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Withers
keywords: X-ray computed tomography; plasma electrolytic oxidation; porosity; scanning electron microscopy; titanium