Evaluation of the atmospheric corrosion resistance of AISI A-36 steel painted with coatings based on epoxy and poly(urethane) resins using semi-accelerated testing

Abstract

The influence of temperature, humidity, salinity, and the number of wet-dry cycles in the atmospheric corrosion resistance of the AISI A-36 steel, painted with coatings based on epoxy and poly(urethane) resins was studied. The aim of this work is to present an alternative to the accelerated and field tests developing a semi-accelerated test for evaluating the resistance and durability of a protection system that is applied to a specific environment for one year. The samples were exposed in a corrosion cyclic test chamber for 2000 h with fixed parameters of temperature, relative moisture of air, salinity, and a number of dry-wet cycles. Mass loss of substrate in the scratch area was measured after each 250 h of testing. The second stage of research was the sensibility analysis of the corrosion rate with the change of the reference test parameters. The third stage was the testing of the samples using the cyclic test for 750 h, and the transfer of samples to a marine atmosphere exposure for one year. The mass loss was measured after each 60-day period of testing. Material characterization involved scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray fluorescence spectroscopy. After polynomial adjustment of the mass loss function associated with the sensibility analysis of the parameter alteration, the estimated life span of the samples ranged from 30 to 38 months.