Abstract: The article exposes contemporary materials and structures for metallurgy. Feasible increase of dynamic forces on the rolling machinery during rolling of billets with masses up to 20 t (Stand No.1 of CWM 1700 HR, «U.S. Steel Košice», Košice, Slovakia, and PJSC «Illich MMPP», Mariupol, Ukraine) is discussed. It is proved that weight of billet, velocities of metal delivery to working rolls and rolling significantly influence the dynamic loads during metal biting. The technical solutions are suggested which would allow the steady rolling process of billets with masses up to 20 t and prevent accidental failures of frame parts, chocks and main lines.
Abstract: The article deals with heat liberation of barium cements, which influences the crack formation in mass concrete structures. The results of heat release and physical testing of barium cements with a different content of BaO are presented in this paper. The strength of cement and its setting time will decrease significantly, if the content of BaO in clinker is high (about 47%). This cement is characterized by a low water requirement and heat liberation. Properties of cement with a low content of barium oxide (5.5%) are close to the properties of the standard Portland cement. In this case heat liberation is low in the initial period of hardening, but at the later stage it exceeds the exotherm of a reference sample. A small amount of BaO in cement clinker reduces the exothermic effect and increases the thermal crack resistance of concrete.
Abstract: The article considers innovative materials that are recommended to be used as a coating for reinforcement of bearing structures of high-rise buildings, bridges, tunnels and underground structures, and as a coating for storagetanks of crude oil instead of high-alloy steel grades 20H23N18, 08H18N10. Nanostructural alloy coating Fe-Ni (> 80% Fe) and alloy coating Fe-Ni-Cr (> 70% Fe), containing in addition to α-Fe a new phase ε-Fe with hexagonal close-packed lattice (GPUr) were obtained by high frequency periodic current at atmospheric pressure and room temperature. Existence of phase ε-Fe was confirmed by X-ray diffraction method, electron-probe test with an electronic probe, scanning atomic force microscopy. Phase transition α-Fe → ε-Fe was observed in the deposition process. A special feature of this phase is the presence of a nanocrystal structure. The main factors in the formation of the hexagonal system are the frequency and duty cycle. The maximum number of ε-Fe phase in the Fe-Ni alloy is 30% and the alloy Fe-Ni-Cr is 20%. This phase has an essential effect on the producing characteristics of the studied coatings. Due to the corrosion resistance in the chloride ions environment Fe-Ni alloy deposited by a high frequency alternating current is 7.5 times greater than high-alloy steel 20X23H18 and 08H18N10. Additionally the nanostructure plated with Fe-Ni-Cr alloy coating made possible to increase its microhardness. Fe-Ni alloy coating can be used as coatings for storage tanks of crude oil and Fe-Ni-Cr alloy coating can be recommended to harden the supporting structures of high-rise buildings, bridges, tunnels and underground structures.
Abstract: In this paper, we consider a method of increasing biological resistance and biological durability of buildings and constructions that are subject to destruction from the impact of microorganisms activity. This article presents the results of studies of innovative materials in the field of bioresistant building materials. Powders of milled quartz sand and limestone were the fillers for the composites. Limestone used for the experiments is from the Chechnya depostits. We have implemented optimization for the cement composites compositions using the methods of mathematical experiment design. We derived the dependences describing how the bioresistance coefficient, the elastic modulus and the water demand depend on the granulometric composition after 3 and 9 months of aging in the environment of filamentous fungi. We have found that the multifractional compositions have a higher bioresistance coefficient. We determined the fungal resist compositions.
Abstract: The article considers innovative materials for construction. Using mathematical planning methods, we studied how the quantitative composition, the biocidal additive and gypsum content influence on the compressive and flexural strength and density of the composites. We found that the more gypsum in a composition the higher compressive and flexural strength of a specimen. So, with the greatest degree of compositions filling (fly ash – 20 mass fractions, gypsum – 11.2 mass fractions) maximum compressive strength is 72.5 MPa. We determined when the fly ash content rises up to 20 mass fractions per 100 mass fractions of clinker, flexural strength rises too and specimen density decreases. The developed compositions of biocidal cements recommended for use in the manufacture of materials, products and structures for buildings and constructions, operating in aggressive environments.
Abstract: In this article, we consider a method of producing biostable innovative materials in order to improve the biological resistance and durability of buildings and structures based on them. We present the results of the research work focused on the study of the cement composites bioresistance. Powders of milled quartz sand and dolomite were the fillers for the composites. Mathematical methods of experiments design allowed us to derive the dependences describing how the bioresistance coefficient, the elastic modulus and the water demand depend on the granulometric composition after 3 and 9 months of aging in the environment of filamentous fungi. We have found that the multifractional compositions have a higher bioresistance coefficient. We determined that dolomite significantly enhances bioresistance of the samples and Portland cement composites, filled with quartz sand and dolomite, are fungal resist.
Abstract: For the purpose of fire safe construction it is necessary to develop and investigate effects of fillers to flammability of building materials, including composite materials with polymer matrix. In present work we demonstrate the results of such investigation. We have examined influence of chemical composition, amount of mineral fillers to flammability, smoke-forming ability and limiting oxygen index of building materials based on different polymer binders. The experimental data indicate that the main parameter which determines the influence of mineral fillers on the flammability of composites is a specific heat absorbed by the filler. The dependence between limiting oxygen index and specific heat of mineral fillers is revealed for composites with epoxy matrices. This dependence is simple and beneficial for practical use.
Abstract: Innovative materials and structures are analyzed in this paper. On the basis of provisions of the systems analysis the principles and approaches to modeling of processes of contact and condensation curing of silicate materials are developed. The mechanism of contact and condensation process on macro - and mesolevels of system is presented. There are provisions of synergetic at its base: formation of an infinite cluster of a framework of a raw from the power links connected by a contact condensation crossing point as a result of redistribution of an unstable phase calcium-silicate knitting between sources and drains of structure-forming elements. Theoretical modeling of intergrain condensation at the base of which there are submodels of the squeezed deposit and a capillary porous body is executed. The nanosized filler has a polyfunctional influence on the structure and properties of calcium-silicate and cement materials, takes part in the formation of new chemical compounds and the structure of pore walls.
Abstract: The article examines the impact of nanodefects on the reduction of the crystals strength. A summary of the authors research results is illustrated by the analysis example of the NaCl crystal destruction process from the standpoint of strength quantum theory. As the base experiment is seen testing the dry and wet a salt crystal made by academician A. Ioffe. The authors research aim was a little-studied patterns of the crystal lattice destruction quantum mechanism. The article gives a brief historical background of the research in this area. The first section discusses the rystal cell dynamic characteristics change as a result of destruction. Assesses self-resonant frequency of an atom at a lattice point of the crystal before and after the destruction. In the second section of the article examines the relationship between the natural frequencies of the atoms in the lattice and elastic energy wich accumulated in the crystal body in the force loading process. The main attention is paid to theoretical modeling of the links strength between atoms in the crystal surface layer. We study the strength dependence of these relationships to the availability of nanodefects on the crystal surface. There are modeled bond strength to clean the crystal surface, as a result of the surface lattice electrification when atoms capture free electrons and for the case when jobs of atoms in the crack are filled with the external environment atoms. The calculations confirm the validity of the proposed theoretical model of reduction or the hanging of the crystals strength by the atoms interaction with the external environment.