Nanotechnologies in Construction: A Scientific Internet-Journal

197-203

Authors: Boldyrev A.M., Sizintsev S.V., Sannikov V.G., Pershin V.F.

The short-term existence of the melt in the weld pool and its overheating, a large temperature gradient near the interface and two-dimensional crystallization centers, in the form of fused grains at the weld pool boundary, reduce the probability and rate of formation of crystallization centers in the liquid phase. This leads to the formation of a coarse-grained columnar structure of the weld metal, which, in combination with defects arising during crystallization, is less ductile than the fine-grained rolled metal being welded, and often causes brittle fracture of the structure. Therefore, obtaining a fine-grained structure of the weld metal is a constant problem in the welding industry. It is now generally accepted that the most effective way to obtain a fine-grained weld metal structure is to modify the weld pool. At the same time, micro- or nanoparticles of refractory metals or their chemical compounds (inoculators) are introduced into the weld pool from the outside, as ready-made crystallization centers.

216-222

Authors: Belozerov V.V., Belozerov Vl.V., Golubov A.I., Kalchenko I.E., Prus Yu.V.

Introduction. To determine the effectiveness of fire-retardant coatings (FRC), a system of methods for fire and high-temperature testing of fire-retardant materials and structures made of themis being used. However, there are no methods and means that could provide current effectiveness of fire protection, and existing methods cannot be applied to determine fire resistance of building structures with fire protection, they set only a group of the effectiveness of the flame retardants. Therefore, to assess the quality and durability of the FRC, in case they provide the parameters of thermal stability of the protected materials, structures and elements of the engineering systems of the objects, it was necessary to develop a quickmethod and a portable diagnostic complex of fire-retardant coatings (PDC FRC). Methods, models and tools. Based on a system analysis of the existing fire protection technologies for building materials from wood, metals, rubber and polymers, a rapid analysis methodology and PDC for thermo-electro-acoustic (TEA) sensing of FRCs using thermo-acoustic methods have been developed. That made it possible to determine thermal conductivity, the ultrasound speed and its absorption coefficient in the FRC, as well as to conduct a comparative analysis of the «FRC image» obtained on a BETA-analyzer with measured characteristics, based on which to calculate the time of its operability. Results and discussion. The PDC of FRC consists of a case with a laptop, with the immitance meter and a two-channel oscillographic attachment connected to the laptop, to the inputs of which a TEA-zonding unit is pressed, pressed to the FRC of the tested object (structure, material, cable), by thermal, electrical and acoustic signals from which the laptop software identifies the properties and stages of operational stability of the FRC. The PDC of the FRC and the proposed approach allowed us to synthesize a model of the Internet system of TEA - diagnosis of FRC and of the monitoring of the operational stability of the protected materials. The novelty of the study is protected by patents of the Russian Federation. Conclusion. The proposed approach and the PDC of the FRC made it possible to implement a quickanalysis of the FRC at the facility and to synthesize a model of the Internet system of TEA-diagnostics of FRC, which can become the basis of the national supervision system for the given area.