Introduction. At present, intumescent fire-retardant coatings for building structures are widely used to ensure compliance with regulatory fire safety requirements for buildings and structures. Through use of fire-retardant coatings, their protective properties inevitably degrade due to exposure to external factors, which typically result in various defects, loss of adhesion and reduced effectiveness. At a certain stage, the coating stops performing its protective functions and must be replaced. Therefore, it is highly relevant to study the aging processes occurring in intumescent fire-retardant coatings and to determine the preservation of their properties during service.

Aim. To investigate the mechanisms and the influence of factors in an open industrial environment on the degradation of intumescent fire-retardant coatings based on an epoxy-acrylate binder.

Materials and methods. This study analyzed samples of a fire-retardant coating selected from a facility operated in the Irkutsk Region for one year. Microphotographs of the samples and infrared absorption spectrums are presented; the spectrums were recorded using a Fourier transform spectrometer in the range of 4000–400 cm^–1 in the form of KBr tablets in accordance with State Standard R 57941-2017. A qualitative interpretation of the spectrums was performed based on an analysis of the characteristic absorption bands of the functional groups of the polymer matrix and its individual components.

Results. Microscopic analysis of the samples revealed the presence of cracks in the fire-retardant coating layer and its highly porous structure, which creates a capillary system that promotes the condensation of water vapor. Based on IR analysis, it was established that the coating sample exhibits intense absorption in the OH-group range (3500–3200 cm^–1), which confirms the coating’s high degree of moisture absorption from the environment.

Conclusions. After 1 year of operation in an open industrial atmosphere, the intumescent fire-retardant coating based on an epoxy-acrylate binder begins to degrade. The porous structure of the fire-retardant coating creates a branched capillary system, resulting in hydrolytic destruction of the main component responsible for the formation of the foamed layer–ammonium polyphosphate.

Introduction. A fire-retardant intumescent coating system, typically consisting of several layers, including a primer layer, not only needs to retain its fire-retardant properties but also ensure the corrosion resistance of the metal structure throughout its service life. A properly selected primer layer, when applied according to the specified application technology, allows to create an effective fire-retardant coating system.

Aim. In this article, the influence of various atmospheric factors on the adhesion and corrosion resistance of different anti-corrosion primers based on glyptal, urethane-alkyd, and epoxy resins, which are part of a fire-retardant intumescent coating system with an epoxy-acrylate binder, is investigated.

Materials and methods. Ten cycles of alternating temperature exposure were conducted in parallel according to State Standard 27037-86, along with 15 cycles of climatic exposure according to Methods 6 and 13 of State Standard 9.401-2018, and the change in the adhesion characteristics of intumescent fire-retardant coating systems with various primer layers based on glyptal, urethane-alkyd, and epoxy resins was evaluated. The microstructure of the boundary between the steel plate and the primer layer of the coating system was investigated using an electron microscope. The degradation of the primer coatings was evaluated using IR spectroscopy methods.

Results. It was found that both the adhesion and corrosion characteristics of the investigated intumescent fire-retardant coating depend on the type of primer coating used.

Conclusions. The use of an epoxy primer is preferable to ensure the long-term service life of the intumescent fire-retardant coating, especially in open industrial environments.