Abstract
Atmospheric plasma spray (APS) deposited ceramic coatings of zirconium boride (ZrB2) and hydroxyapatite (HAp) were inspected using Data-Constrained Modelling (DCM) of X-ray Micro-Computed Tomography (X-ray mu-CT) datasets to evaluate coating porosity. The DCM approach was used to quantify the porosity and void distributions in the coatings. The results from the 3D analysis were compared to 2D porosity and void distributions determined from the image analysis method. The 3D porosity determined from the ZrB2-1 model, 24.7%, agreed well with the 2D porosity estimation of 22.1 +/- 2.6%. Additionally, the 3D porosity determined from the HAp-1 model, 22.8%, was marginally greater than the estimated 2D porosity, 19.8 +/- 2.1%. However, a comparison of the 2D and 3D void distributions revealed that a 2D assessment poorly predicted the 3D microstructure of coatings and cannot be used to infer properties that depend strongly on the 3D void network. The DCM method has the ability to include the effect of fine-structure details over the 3D scan volume and hence incorporated micropores and cracks that are typically overlooked during traditional porosity inspections. Furthermore, the 3D analysis demonstrated the deficiencies in typical CT segmentation methods applied to data with a moderate CT resolution size, which was 5.4 mu m. The superior DCM approach enabled the quantification of pores below the CT resolution limit that would not have been accurately modelled using typical CT segmentation methods.
NSTL
Elsevier