ASSESSMENT OF DURABILITY OF COATINGS IN DIFFICULT STRESS CONDITIONS

Abstract

The mechanical properties of protective powder coatings based on epoxy-polyester applied to steel substrates were studied. The mechanical characteristics of coatings, as well as their influence on the behavior of samples under mechanical loading, were determined. Tests of samples with coatings, created by Nano indentation methods, with subsequent processing of experimental data using standard analytical simplified models and using numerical finite element modeling were performed. In tensile tests it was demonstrated that presence of coatings leads to changes in the nature of fracture of the samples. In stability tests, the results of experimental data were compared with the results of analytical and numerical calculations, which demonstrated the effect of coatings on the stability of thin-walled samples. The mechanical properties of samples with coatings on one or both sides of the sample were studied, which also confirmed the elastic modulus of the studied coatings at a level of up to 10 GPa (with the average value for bulk materials up to 3.5 GPa). In the process of testing at elevated temperature, the importance of ensuring tight clamping of the samples was established, in the absence of which significant increase in the measurement error takes place. Due to temperature deformations, stiffness of the samples is reduced and, accordingly, deviate from conditions of hard seal assumed in calculations. The results obtained are aimed at developing an understanding about mechanical properties, as well as about methods for changing and calculating mechanical properties, thin protective coatings used in various industries and, in particular, a wide class of coatings used to protect aircraft structural components from corrosion.