Analyzing Porosity in Thermal Barrier Coatings: Edge Detection of Images Using MATLAB

Thermal spray has been widely used in aerospace and manufacturing industries for a variety of applications, especially for coating technology. The process-structure-property correlations to the coating technology are very important for achieving lifetime durability and sustainability. An important measure of coating integrity is the porosity of the surface structure. Traditionally porosity of the deposit is obtained by microscopy of the surface and the use of software based on grayscale threshold setting. This paper evaluates the grayscale threshold method using MATLAB for determining porosity on test images of a thermal barrier coating (TBC). Also, it is found that the porosity of test images can be assessed within 0.5% by the above method.