Coating microstructure characteristics are dependant on the applied preparation and evaluation techniques. Three areas of microstructure characterization will be discussed.

1. Nano-structure evaluation by x-ray diffraction method:   The method is based on the diffraction peak broadening measurement. The factors that could influence results include the diffraction pattern scan geometry, x-ray beam wave length, the standard sample using and preparation, input of dislocation density, short range ordering and mathematic models applied for the diffraction profile characterization.
2. False diffusion zones:   The coating-substrate interface area is significantly influenced by the sample preparation procedure. It will be shown that the pseudo-diffusion layer could have thickness around 10-20 mm, and this artifact typically appears between coating and substrate from soft and ductile materials such as Al, Cu, Ni, and Ti.
3. Microstructure. Depending on the polishing technique utilized,  the same coating  cross-section could reveal porosity from ~0.5 to ~4 %, the oxide inclusions could be visible or not, and number of micro-crack can vary by a factor of ten. Some examples of metallographic techniques for metal and ceramic coatings will be introduced and discussed.