Abstract: A promising mode of magnesia binder use in construction is dry building mixtures production. Depending on purpose they can be self-leveling, plastering, painting, primer, putty, etc. To produce those different binders, including magnesia one, can be used, depending on the desired aesthetic, environmental and anti-bacterial properties. It can be used in children's, medical, public institutions, and residential premises. The most preferable use for magnesia dry building mixes (MDBM) is as plaster for inner or outer buildings decoration. Plasters for external use have to be light, creating a ‘breathing’ coating that prevents thermal cold bridges formation, has high vapor permeability that can adjust to the equilibrium moisture content of magnesia design on the whole, has good adhesion to the coated surface and adequate frost resistance. Ordinary Portland cement and lime-silica binders are most often used for such products. Unlike materials based on these binders, magnesia products are characterized by rapid strength development under natural conditions. Therefore, the use of magnesia binders which allow obtaining high-strength, environmentally friendly and bioresistant materials for construction is particularly interesting.
Abstract: The article addresses the issue of improving the accuracy of power electromechanical systems design. The performance of power electromechanical systems relies on the performance of permanent magnets used, which is nonlinearly dependent on temperature. It is shown that the calculation error introduced by this nonlinearity cannot be described accurately enough with one equation. It is also shown that the performance of thermally unstable magnets can degrade abruptly at a certain temperature, which causes additional and unpredictable decrease in electromechanical system’s performance.
Abstract: The article analyzes the promising polymeric materials to be used as a template in the manufacture of magnetoactive elastomers (MAEs). MAEs belong to the group of so-called smart materials; they can be used to creeate new techniques and technologies. MAEs are promising materials used to manufacture the working chamber of pumping units for the implementation of peristaltic movements in highly viscous and highly condensed substances. Environments, which is in contact with an element of MAEs, specifically high viscosity asphaltenic oil, impose substantial restrictions on the choice of the polymer matrix for its production, taking into consideration the influence of the material selected to modify the rheological properties of the resultant material. Studies of fluoropolymers basic properties have been conducted. According to their results it is concluded that fluorine-containing polymers can be used as the polymer matrix to manufacture MAEs in contact with aggressive high viscosity substances.
Abstract: The process of dimensional fused silica etching was offered. The production process of molycoat by magnetron sputtering of molybdenum target in inert gas (Argon) on vacuum distillation unit (NIKA-2012 TN) was examined. The coat quality (delamination, discontinuity) was analyzed; the influence of the first kind internal strains on the type of the observed defects was determined. The research was conducted by means of microscopic and X-ray diffraction analysis. It has been established that the internal strain value in the coat depends on the sputtering gas (Argon) flow rate, and, consequently, its pressure in the magnetron system for molybdenum sputtering. Zero stresses are registered under Argon's flow rate, which is 7.5 L/h. Influence of internal stresses level in the barrier coating on the quality of etching dimple.
Abstract: The scientific interest in amorphous and nanocrystalline materials is associated with the expectation of different structural and size effects on the properties of solids, as applied attention due to the possibility of fundamental changes in the properties of polycrystalline materials. Numerous experimental studies indicate the following regularities: the higher the degree of equilibrium of the melt prior to crystallization is, the better quality has a solid metal. In industrial conditions the equilibrium state of the melt is achieved by the technology for heat treatment of the melt. The scientific rationale for this technology is the results of studying the temperature and time dependence of physical properties. The present work describes the analysis of the physical properties of liquid amorphous solder, conducted heat treatment of the melt and the study of the samples mechanical properties in the solid state. Amorphous ribbons obtained by the technology for melt heat treatment, ceteris paribus withstand higher loads in tension, exhibit better ductility and are characterized by high stability of the results. This fact confirms a more uniform material structure.
Abstract: The paper presents a method for increasing stainless steel 04Cr25Ni6NMo3 corrosion-resistant properties. An increased corrosion resistance develops due to the stabilization of the structure of titanium steel. The titanium additive changes the phase composition of the carbide phase and enhances the corrosion-resistant properties. Change of the phase composition of the carbide phase is analysed by means of the thermodynamic modelling.
Abstract: The paper presents a thermoconcentration and capillary mathematical model, describing the formation of 10 to 100 nm structures in the surface layers of binary alloys irradiated by low-energy, high-current electron beams of submillisecond duration. The model is studied by the example of “ferrum - carbon” and “titanium – carbon” systems. It comprises Navier-Stokes equation, thermoconductivity and diffusion equations, as well as surface kinematic and dynamic boundary conditions. The effect of electron beam on material is specified as various temperature and concentration gradients. A dispersion equation for thermocapillary waves in nanowavelength range is developed and analyzed with thin layer approximation. The critical wavelength, leading to this instability, is revealed. It is found out that its values are 17.39 nm for Fe-С and 69.7 nm for Ti-C at the depth of penetration ~ 10-5 m. Wavelengths are compared to the dimensions of crystallization cells and structures, which are formed in them. The paper shows that the model provides a rational explanation of registered regularities.
Abstract: The paper considers the problem of nanostructured strengthening of spring steels and springs, the idea of steel nanostructured strengthening determined not only by grain sizes but also by subgrain sizes is justified. Design schemes of thermal strain nanoscale substructure patterning in spring material produced by hot and cold coiling were implemented. Patterning of nanoscale substructure was experimentally proved. Strength analyses of spring steels and springs showed the dominant effect of nanoscale substructure on spring limited life increasing not less than 10 times at cyclic fatigue tests. Spring compression at cyclic loading decreases 10 times.
Abstract: The performed studies of the application features of the cutting tool, hardened by laser pulsed radiation are based on the comprehensive cutting process analysis. In this approach, the modeling results of the cutting process with hardened tool allowing to define the area of the effective use of laser treatment (LT). In particular, the increase in the tool life only for the certain values of the cut depth at the fixed irradiation energy was observed. The causes of the observed phenomena were determined based on durometric researches and studies of the microstructure in the contact zone. The measurements were performed for the cutters (steel R18) after turning structural steel 12Kh2N4A under various cutting modes. It was found that the processes of tool material softening, observed at turning with high feed values, limits the scope of cutting conditions by hardened tool. It is shown that LT leads to increased tool life, operating at the cutting conditions when the growth of tension thermodynamic in the cutting zone does not result in the development of softening processes. It is established that the area cutting modes are restricted to the values of cut depth not exceeding 1.5 mm (V=42.5 m/min, s=0.2 mm/rev) for the investigated pair of tool-workpiece (R18-12Kh2N4A). Tool life increases by more than 4 times compared to the durability of the non-irradiated tool provided the optimal combination of laser processing and hardened tool cutting modes is achieved.