EXPERIMENTAL INVESTIGATIONS OF MECHANICAL CHARACTERISTICS OF POWDER COATINGS ON AN EPOXY-POLYESTER SUBSTRATE BY NANOINDENTATION

Nanoindentation of the surface of powder epoxy−polyester-based paint-and-lacquer coatings, deposited on a steel substrate, is described. The effect of the testing method on the identified mechanical properties is analyzed. The measurement results, obtained by a spherical indenter and a Berkovich indenter, are compared. The reduced modulus of elasticity, Young modulus, and hardness of the coatings are evaluated. The obtained experimental data demonstrate a substantial dependence of the determined mechanical properties of the powder coating on the type of the indenter. When a Berkovich indenter is used, the found Young modulus for coatings (0.6 GPa) is underrated in relation to the properties of the coatings, known from macro experiments (3 GPa). When a spherical indenter is used, the Young modulus is overrated (6.3 GPa).