RESUMO
A review and analysis of changes in mechanical properties of basalt fibers (BF) and basalt composite materials under effects of aggressive environments in reference to foreign and Russian scientific literature has been carried out. The changes in the physical and mechanical properties of the fiberglass (FG) and basalt plastic (BP) have been compared. The analysis shows that BF is a good alternative to fiberglass for elaboration of composite materials for various purposes. In the most aggressive alkaline environments, BP resistance is higher as compared with that of FG. If required, BF resistance to chemically active media could be increased by midifying its composition and applying protective layers and heat treatment of fibers. For extended use of BP as an effective structural material under various climatic conditions, including in the Arctic, long-term tests of 10 or more years are advisable and relevant, with control of changes in their mechanical parameters and an analysis of processes of climatic aging developing in BP.
RESUMO
Rods of basalt plastic armature (BPA) of a periodic profile with diameters of 6, 8, 10, 16 and 20 mm on the basis of an epoxy matrix were exposed for 30 months on open stands in a moderately warm marine climate of Gelendzhik and 28 months on similar stands in an extremely cold climate of Yakutsk. For initial and exposed BPA samples, changes of mechanical parameters were determined. After the exposure in Yakutsk, an increase of ultimate compression strength by 4-12% is found, depending on the diameter of rods. After the exposure in Gelendzhik, this indicator decreases by 10-17%. Using methods of thermomechanical analysis and dynamic mechanical analysis, linear thermal expansion coefficient and glass transition temperature of epoxy matrix were measured. In an initial state, a transition from a glassy state to a highly elastic one is discovered: an α 1 -transition at 118 °C and an α 2 -transition at 149 °C. After climatic action, there were detected a shift of α 1 -transition to low temperatures and a shift of α 2 -transition to higher temperatures. Reasons for the change of temperatures of transitions are weakening of a molecular layer and post-curing of the epoxy matrix in a surface layer. These effects are accompanied by an increase of the linear thermal expansion coefficient, moisture diffusion coefficient and maximum moisture saturation after the climatic action on BPA. Fractographic studies discovered presence of pores in a structure of BPA with sizes up to 10-20 µm, a quantity and size of which increase by 20-40% after the climatic action. In general, the studied BPA has high climatic stability and can be used for a long time under the extreme climatic conditions.
