Significance and Use 5.1 All these test methods are recommended for elementary quantification of the morphological properties of porous coatings bonded to solid substrates. 5.2 These test methods may be useful for comparative evaluations of different coatings or different lots of the same coating. 5.3 All the methods should be performed on the same set of images of fields. 5.4 A statistical estimate can be made of the distributions of the mean coating thickness and the volume percent void. No estimate can be made of the distribution of intercept lengths. 5.5 There are limits to the accurate characterization of porosity, depending on spacing between the lines in the line grid (or points in the point grid) and the individual and cumulative fields used for the measurements. Increasing the size of the fields, increasing the number of fields, or decreasing the grid spacing will increase the accuracy of the measurements obtained. 5.6 This method may be suitable for ceramic coatings if an accurate coating cross section can be produced. Producing an accurate ceramic coating cross section may require other techniques than standard metallographic techniques. 5.7 For coatings having a mean thickness less than 300 microns, it is not recommended to attempt to determine the volume percent void or the mean intercept length.Scope 1.1 This test method covers stereological test methods for characterizing the coating thickness, void content, and mean intercept length of various porous coatings adhering to nonporous substrates. 1.2 A method to measure void content and intercept length at distinct levels (“Tissue Interface Gradients”) through the porous coating thickness is outlined in 9.4. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
