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The structure of the developed epoxy coatings using IR spectral analysis and corrosion resistance by determining the permeability index in the aggressive environment of river water during = 6552 h at a temperature range T-258...303 ± 2 K was investigated in the article. It was shown that the process of structure formation of epoxy coatings is influenced by the change in the ratio of nano-disperse and fibrous fillers in epoxy ED-20 oligomer. Significant structural changes for epoxy coatings were observed at wave numbers: v=570 cm-1, v=840 cm-1, v=1045 cm-1, v2962 cm-1, which indicates their degree of crosslinking. A study on the change in the permeability index in the environment of river water was carried out with consideration of rational proportion of dispersive fillers in the epoxy binder, which made it possible to create an effective barrier to the penetration of aggressive ions and water molecules to the base. A decrease in the permeability of protective coatings by 1.8... 2.0 times relative to the epoxy matrix was achieved. In addition, a visual analysis of the surface coatings operated under the influence of river water at variable temperatures was carried out. For the epoxy matrix and composites containing one filler, defects in the form of cracks and peeling were observed, which are associated with the course of physical and chemical processes of sorption and diffusion of an aggressive environment. In addition, such coatings are characterized by a tendency to overgrowth with green algae of the genus Spirogyra. For the coatings containing a rational combination of two fillers, the absence of defects and biological fouling was observed. [ABSTRACT FROM AUTHOR]

Impact loading curves and fracture energy of the notched 12Cr1MoV ductile steel specimens are analysed. The qualitative description and quantitative parameters are obtained for major stages of ductile and brittle fracture depending on the shape of the notch and the stress stiffness ahead. It was shown that a zone with enhanced plasticity forms in the vicinity of V-, U- and I-shaped notches at 20 °C testing temperature, giving rise to ductile fracture. The stress stiffness at the notch tip increased with testing temperature reduced to −40 °C. We demonstrated that the size of shear lips on a fracture surface is a quantitative characteristic of fracture. Using this approach, which is close by nature to non-linear fracture mechanics, together with the quantitative description of fracture surfaces, a physical-mechanical scheme of the specimen fracture was suggested for the case of enhanced and localized (constrained) plasticity near the stress concentrator tip. [ABSTRACT FROM AUTHOR]

A new automated model of continuous-caster rollers is described and a study is made of the effect of a brief interruption in the casting operation on the temperature fields in these rollers. A comparison is made between the temperature cycles in the model roller and rollers on operating continuous casters. [ABSTRACT FROM AUTHOR]

It was shown previously that cyclic loading can be used to extend the fatigue life of sheet plastic materials subjected to the preliminary impact-oscillatory loading. This type of loading causes dynamic non-equilibrium processes (DNP) in materials, which lead to the formation of dissipative structures in materials and on their surface. The density of these dissipative structures is less than that of the base metal. In this paper, the results of investigations into the relief and hardness of surface layers modified by impact-oscillatory loading are analyzed on the example of five structural materials. The signs of a regular, orderly system of microextrusions formed on flat surfaces of all materials due to DNP are considered along with the alignment of roughness parameters R z and R a of relief profiles. The effect of impact-oscillatory loading is one of the main causes that lead to the extension of the fatigue life of materials.

Regularities of steel structure degradation of the "Novopskov-Aksay-Mozdok" gas main pipelines (Nevinnomysskaya CS) as well as the "Gorky-Center" pipelines (Gavrilovskaya CS) were studied. The revealed peculiarities of their degradation after long-term operation are suggested to be treated as a particular case of the damage accumulation classification (scheme) proposed by prof. H.M. Nykyforchyn. It is shown that the fracture surface consists of sections of ductile separation and localized zones of micro-spalling. The presence of the latter testifies to the hydrogen-induced embrittlement effect. However, the steels under investigation possess sufficiently high levels of the mechanical properties required for their further safe exploitation, both in terms of durability and cracking resistance.