Henry Moseley X-ray Imaging Facility, The University of Manchester , Manchester M13 9PL, U.K.
Corrosion and Protection Group, School of Materials, The University of Manchester , Manchester M13 9PL, U.K.
ACS Appl Mater Interfaces. 2016 Apr 6;8(13):8801-10. doi: 10.1021/acsami.6b00274. Epub 2016 Mar 22.
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.
等离子体电解氧化 (PEO) 越来越受到关注，因为它可以在金属上形成陶瓷涂层，用于需要多种涂层性能的应用，例如耐磨性和耐腐蚀性、低导热性和生物相容性。涂层中的孔隙率会对涂层性能产生重要影响。然而，由于孔径范围广且涂层形态复杂，因此对涂层中的孔隙率进行定量可能很困难。在这项工作中，使用高分辨率 X 射线计算机断层扫描 (X 射线 CT) 对钛上形成的 PEO 涂层进行了检查。通过对使用 X 射线 CT 和扫描电子显微镜获得的特定涂层特征的表面视图和横截面视图进行比较，对观察结果进行了验证。X 射线 CT 技术能够分辨出体积至少为 6 μm(3) 的孔隙。此外，还揭示了大孔的形状，并证明了孔隙、涂层表面上的结节和钛基底上的凹陷的位置之间存在相关性。这些孔隙构成了涂层体积的 5.7%，它们的位置和形态表明它们是由熔融涂层中释放的氧气产生的。
