Bulletin PNRPU. Mechanical engineering, materials science

Studies of the antifriction properties of composite materials based on epoxy binders have been carried out. To prepare the modified compositions, an epoxy diane resin ED-20 (GOST 10587-84) was used. As cross-linking agents for cold curing, aminoalkylphenol (AF-2) (TU 2494-052-00205423-2004) was used, and hexamethylenediamine (HMDA) (TU 6-09-36-73) for hot curing. As the filler, wollastonite Brand MiVoll 10-97 (TU 577-006-40705684-2003) of domestic production of CJSC Geokom with a characteristic ratio of length to grain diameter of 15:1. Surface-active substances (surfactants) were used to activate the surface of wollastonite. The influence of the amine hardener structure and the type of surfactants used to activate the surface of the mineral filler on the wear resistance, hardness, and static friction coefficient of epoxy polymers was studied. The tests were carried out on an automated friction machine "Tribometer, CSM Instruments" (Switzerland). The effect of the modification of epoxy como positions with surface-activated wollastonite on the hardness of epoxy polymers has been studied by the method of Barkol. The wear resistance of samples from the epoxy composition was measured on a vertical optical meter IZV-1 with an accuracy of ±0.001 mm. Thus, the compositions of antifriction materials based on epoxy resins modified with surface-activated wollastonite have been developed, the results of the study of the effect of surfactants on the modifying effects of wollastonite are presented. It was found that activation of the surface of natural wollastonite causes an improvement in the number of antifriction properties of epoxy materials filled with it. Moreover, a more significant increase in hardness and wear resistance is observed when cured with hexamentylenediamine, and when the AF-2 cures, the static friction coefficient also decreases. At the same time, it is more promising to use alkyltrimethylammonium chloride with a longer alkyl radical.

Investigations of powder alloys of the Fe-(30-36)% Ni system based on carbonyl powders are presented. The dependence of the austenite grain size and the concentration of components on the structural features and properties of powder Fe-Ni alloys is shown. To carry out the experiment and studies, the metallographic analysis, the method for measuring the austenite and martensite grains, X-ray phase analysis, X-ray diffraction analysis, spectral analysis, and magnetometric method were used to determine the temperatures of the α-α transformation. When studying the microstructure of Fe-(30-36)%Ni alloys, it was found that an increase in the concentration of nickel promotes the coarsening of the average grain size of the austenite, and the grain coarsening promotes the acceleration of the austenitic-martensitic transformation. In alloys with nickel content in the range of 30-32%, the phase transformation temperature increased with increasing minimum grain size of martensite in direct proportion to the nickel content, the critical austenite grain size was 1-3.5 microns. It is established that the transformation in alloys with 30.3-31.93% nickel occurs in a wide range of temperatures (70-120 degrees), and in alloys with 34.35-36.33% nickel - in a narrow (1-2 degrees). It is shown that as the nickel content increases from 30 to 36%, the grain size increases and the temperature of the phase g-α transformation increases by 75 K, and the fraction of martensite formed increases by a factor of 5. It was found that the decomposition of austenite in iron nickel alloys (30-32% Ni) was in the range 70-92%, with a Ni content of 33-36%; the decomposition of austenite was insignificant: 2-15%. It was established that when the samples were cooled to 5 K in a field with a strength of 5 kЕ, the value of the magnetization increased to 113-189 emu/g. It was found that a decrease in the critical grain size provokes the transformation into iron of nickel alloys.

The article is devoted to the creation of environmentally friendly, technologically efficient and cost-effective high-performance integrated circuits for the processing of lead-containing industrial products and wastes, in particular, silicate slag (SS), formed by melting electrolytic copper sludge, with commercial production of single products. Among the possible ways of the recovery school stands out vacuum distillation, which is considered one of the most effective and environmentally friendly methods for the separation and purification, processing and refining of various metals. To analyze the behavior of multicomponent alloy processing, pre-selection of temperature and pressure of the system, evaluate the effectiveness of component separation in a vacuum distillation using phase diagrams temperature - composition “ T-x ”, pressure - composition “ p-x ”. The aim of the work is calculation of the equilibrium “gas-liquid” VLE (vapor liquid equilibrium), including the dependence of phase composition on temperature ( T-x ) and pressure ( p-x ) for Pb-Sb alloy with vacuum distillation based on the model MIVM (мolecular interaction volume model), as well as determination of thermodynamic parameters of the process. calculation of the activity coefficients of components of Pb-Sb alloy was performed using three-dimensional model of molecular interaction мolecular interaction volume model. the calculation of VLE diagrams using the model MIVM. In the temperature range 823-1073 K the calculated saturated vapor pressure (Pa) Pb (0.0263-14.9)·10-2 and Sb (3.954-273.66). High values of the ratio = (15.04-1.83)·103 and the separation factor logβSb = 3.18-4.27 create a theoretical background for the selective separation of these metals by vacuum distillation, when the antimony is enriched in the gas phase (βSb > 1), and lead in liquid. The mole fraction of lead in the gas phase у Pb = (6-5855)·10-6 increases with increasing temperature 823-1073 K and the molar fraction of the metal in the alloy х Pb = 0.1-0.9. Using the MIVM model calculated activity coefficients of antimony γSb = 0.771-0.998 and lead γPb = 0.811-0.998 for Pb-Sb alloy with different composition in the investigated temperature range. For phase diagrams VLE can be used by the lever rule (rule lines) to help predict quantities of substances, residues and sublimates at a predetermined temperature. For the phase boundary “liquid-gas” Pb-Sb alloy the values of the excess Gibbs energy, enthalpy and entropy: QUOTE = -(0.145-0.44) kJ/mol; = -(0.156-0.427) kJ/mol; QUOTE = 0.0100-0.0565 J/mol·K.

In the article the brief review of scientific researches of process of stress corrosion cracking of welded joints of high-alloyed chromium-nickel steels is given. Welded joints, from the standpoint of the general theory of corrosion fatigue of metals, are among the most complex objects. During their operation, a number of problems arise related to the heterogeneity of the material properties, the complexity of the structure, the presence of structural and technological stress concentrators, residual stresses, etc. The characteristic features of corrosion cracking, cited in the studies of Russian and foreign scientific schools, are noted. The main types of corrosion damage at various sections of the welded joint are examined, namely corrosion of the weld metal, damage to the zones of thermal influence, knife damage occurring at the boundary between the joint and the base metal. The models of nucleation and development of cracks in the mechanism of intercrystalline corrosion are analyzed. The article provides information on the causes that cause the steel's propensity to intercrystalline corrosion. The data on the effect of heat treatment on the tendency of the weld metal to intercrystalline corrosion are systematized. The main regularities of corrosion-resistant alloying are noted. The data on the methods for preventing intercrystalline corrosion and reducing the tendency of the weld metal to stress corrosion cracking are given. Methods for estimating the tendency of weld metal to stress corrosion cracking are classified. The analysis of methods for preventing the tendency of welded joints to stress corrosion is given: metallurgical methods related to the effect on the chemical composition of the weld and the structure of the welded joint, and technological methods associated with controlling the parameters of the welding and heat treatment regime.

The purpose of the work is to increase the efficiency of the еlectrical discharge machining (EDM) of details of hydraulic cylinders and special-purpose products (hereinafter referred to as GC and ISN) by using electrodes (hereinafter EI) with increased EDM properties. All materials used for the manufacture of GZ and ISN parts is the presence of chromium steels in the chemical composition. The presence of chromium improves the EDM resistance of the material, in connection with this, the processing of these details is accompanied by intense wear of the EI. Increasing the wear resistance of EI is an urgent task. It is known that in EDM of hard and refractory alloys, EIs made of composite materials are widely used. At present, composite materials based on copper have been developed, which make it possible to improve the operational properties of the tool electrode. In spite of this, the use of such EI for EDM treatment of chromium-containing steels is not widely used. This is due to the fact that there are no practical recommendations on the use of these electrodes and the influence of the percentage content of the components of the composite material on the productivity and resistance of the EI in the treatment of chromium-containing steels has not been fully studied. To determine the influence of the percentage content of the components of the composite material on the performance properties of the EI, an experiment was conducted on the EDM treatment of chromium-containing steel X12F EI from the composite materials of the systems: copper-chromium; Copper-tungsten; Copper-molybdenum; Copper-graphite, with a different content of constituent components. According to the carried out experiment, and the subsequent analysis, it was established that the electrode of the copper-graphite system with 0.2% graphite content had the most optimal parameters. The received data allow show the expediency of the use of EI from the composite material of the copper-graphite system for machining the parts of the GC and ISN.

The purpose of the research was to study the physical, mechanical and operational properties of electrode tools made from composite materials based on copper with the addition of carbide, carbonitride, titanium carbosilicide in the erosion of tool steel. Composite materials based on copper with different contents of the refractory phase were made by powder metallurgy. During the sintering of the systems “copper-titanium carbide” and “copper titanium carbonitride” chemical interaction was not observed, in the copper-crab-silicate titanium system, dissociation of the compound was established de-siliconization from titanium carbosilicide grains, part of titanium carbosilicide grains was converted to a solid solution of carbon based on Titanium silicide Ti5Si3(C) and small amounts of titanium carbide, silicon carbide and titanium silicide TiSi2. It was found that with an increase in the concentration of the refractory additive from 12.5 to 80 vol.% increases the hardness and strength of composite materials, as well as the electrical resistivity. The lowest porosity (6%) was in materials containing titanium carbosilicide, regardless of its content. The flexural strength was 2 times higher in systems with titanium carbosilicide in comparison with carbide and titanium carbonitride. When investigating the relative wear of the EI during the piercing of tool steel on draft modes, it was established that all the systems studied have better wear resistance than pure copper and copper-tungsten carbide material. The accuracy of the treatment with copper-carbolicidal titanium was higher than with pure copper and other materials studied. The least relative wear during titanium insertion was observed when using an electrode “copper-12 vol.% Titanium carbide”.