Estimation of the domestic materials application possibility in the active part of a high-speed electric generator for micro-GTP

The article discusses the possibility of using domestic materials in a high-speed electric generator. The features of Japanese electrical steel 20NTN1500 and domestic-made electrical steel grades 2420 and 2421 for the stator magnetic circuit are shown. The features of American steel AISI 455 and structural steel grades Steel 40, Steel 40H, Steel 45 are considered in the case of a rotor. A feature of the use of structural steels in the design of the high-speed electric generator rotor for micro-gas turbine plants is the need for precise observance of the rotor heat treatment mode after its manufacture, control of the dimensions and quality of surface treatment.

Microstructural Features and Properties of Al-Cu-Mg Alloy Containing Silver and Cerium

The article presents the results of an investigation of microstructural features and mechanical characteristics of Al-5.0Cu-0.5Mg alloy containing up to 0.4 wt. % Ag and up to 0.1 wt. % Ce. The experiment was conducted using optical microscopy, Scanning Electron Microscopy as well as an electron probe micro-analyzer and Differential Scanning Calorimetry. Samples in cast condition and after heat treatment were examined. The melting temperatures of non-equilibrium eutectics (non-equilibrium solidus), equilibrium solidus and liquidus were determined. The optimal temperature of the homogenizing heat treatment was determined, which was 500°C. Using this heat treatment mode resulted in the elimination of dendritic segregation and complete dissolution of silver in aluminum. Injection of cerium into the Al-Cu-Mg-Ag system during crystallization of the melt is accompanied by the formation of a coarse four-component phase, which has the morphology of polyhedrons, is on the grain boundaries. The estimation of the relation between microstructure characteristics and mechanical properties of the alloy has been made.

Recovery of niobium during comprehensive processing of pyrochlore-monazite-goethite ores

This paper looks at the pyrochlore-monazite-goethite ores of the Chuktukonsk deposit (0.98wt.% Nb2O5) and their processing with the help of acidbased (HNO3, H2SO4) and sulphatization techniques. Nitric-acid pressure leaching was found to be an efficient processing technique for this type of ore: ore size –0.074 mm; CHNO3 = 25%; CH2O2 = 5%; τ = 2 h; solid-to-liquid = 1:9; heat treatment mode: 1 h at 160 oC followed by 1 h at 230 oC. As a result, rare earth metals and manganese are leached to the solution while all of the contained niobium remains in the cake. Two different techniques were tested to recover niobium from the cake. One is based on the use of alkali (NaOH sintering), the other is an extractive leaching technique that combines acid leaching with liquid-liquid extraction of tributyl phosphate in one stage. It was established that niobium mi nerals can be efficiently decomposed when using a mixture of hydro fluoric and sulphuric acids with the concentrations of 4.08 and 8.46 mol/L, correspon dingly, as a leaching agent. At the weight ratio of 1:2:1 of the solid to aqueous to organic phase and after the slurry has been stirred intensively for 5 minutes, niobium fluorides, which form as a result of interaction between hydrofluoric acid and the cake components, can be recovered with a 50% solution of tributyl phosphate in octane. After that they transfer to an organic phase while impurities get accumulated in the solid residue. As niobium-containing cake has a high concentration of silicon, it is recommended to first remove silicon from the cake using a strong alkaline solution.

A Novel Application on the Drive Elements of Using Electrical Contact Resistance and Friction Coefficient for Evaluating Induction Heat Treatment

The load on drive elements under extreme pressure conditions is significantly larger than that used in machine tools. When operating under a heavy load for a long period, large deformation and severe wear between the ball and the track are more likely to occur. To reduce wear, the most fundamental solution is to improve the surface properties of the material. Moreover, heat treatment is the most effective method to improve the surface properties of materials, thereby achieving wear resistance and low friction. It is necessary to develop a new heat treatment technology for wear resistance in extreme pressure conditions. Therefore, this study conducted experiments using a reciprocating friction tester. The responses of electrical contact resistance and the friction coefficient were measured synchronously to investigate wear resistance and low friction of the alloy steels after the induction heat treatment. Then, the results were compared and verified with low-carbon alloy steel after the traditional carburizing heat treatment. The experimental results show that the application of new induction heat treatment technology can not only improve the performance of drive components, but also save time and energy, and streamline the production process of the drive components. Therefore, the results of these wear analyses confirm that the induction heat treatment mode can replace the traditional carburizing heat treatment mode for drive elements.

A review of the synthesis of single-crystal 1D perovskite nanostructures by the hydrothermal method

Recently, the one-dimensional ferroelectric perovskite nanostructures have been of high interest due to a number of unique properties that allow the improvement of the current ceramic nanotechnologies. In order to receive the nanoparticles of a given structure and morphology it is quite important to expand and summary the knowledge regarding the physicochemical processes of the formation and growth of a new phase. Therefore, in this paper, based on the existing works, an attempt to describe the influence of the crystallization mechanism as well as hydrothermal synthesis parameters (such as the reagent nature, pH, concentration, surfactant, heat treatment mode) on the peculiarities of the anisotropic growth and the formation of the one-dimensional perovskite nanostructures was carried out.

Experimental determination of continuous cooling transformation diagram for high strength steel X153CrMoV12

The article is a continuation of the article ,DILATOMETRIC ANALYSIS OF COOLING CURVES FOR HIGH STRENGTH STEEL X153CrMoV12”, which deals with the phase transformations of tool steel X153CrMoV12. The experimental data obtained was used to evaluate the resulting CCT diagram, which consists of seven dilation curves. All experimental samples from dilatometric analyses were then subjected to microstructural analysis and hardness measurements to characterize the microstructure and hardness for each heat treatment mode tested. AFM microscopy was also used to study the carbides present in steels and their size and shape for all selected cooling modes.

Modern methods for studying of phase transformations in high-carbon wire rod to ensure quality of high-strength reinforcement

The structural transformations (formation and decay of austenite) in high-carbon boron microalloyed 80R steel are studied by the differential scanning calorimetry method. The temperatures of the beginning and end of the formation of homogeneous austenite during heating and its decay during cooling, proceeding according to the type of ferritic-carbide mixture with the release of the α-phase of one morphological type, are determined. The obtained results can be used to select one of the main technological parameters of the deformation and heat treatment mode of rolled products — the rational austenization temperature, which ensures the formation of structure and properties in high-carbon wire rod intended for the manufacture of high-strength stabilized reinforcement for iron-concrete structures.

Extruded material based on Bi0.85Sb0.15 for thermoelectric converters

In order to create a sufficiently strong material with thermo- and magneto-thermoelectric figure of merit close to single-crystal samples of material based on Bi-Sb systems, extruded samples of Bi0.85Sb0.15 solid solution were obtained and the effect of composition, heat treatment mode, grain size and tellurium impurities was investigated on their thermoelectric properties in the temperature range ~ 77-300 K and magnetic field strength H up to ~ 74∙104A/m. We managed to obtain extruded material with thermo- and magneto-thermoelectric figure of merit ~6.2∙10-3 K-1 and ~7.2∙10-3K-1 at ~ 77 K, respectively, with strengths ~ 3 times higher than the strength of single-crystal samples of this composition, which are suitable for use in low-temperature thermoelectric converters.

Development of Heat Treatment Mode with Quenching in Different Quenching Environments for the Casing Pipe in Order to Obtain the Required Mechanical Properties

Development of an optimal technology of heat treatment for blanks of the casing pipe made of steel 40H (GOST 4543) is used in the oil and gas industry for casing. It is accompanied by quenching in various environments to ensure guaranteed obtainment of the required mechanical characteristics. These characteristics are specified in GOST 632-80 and met in order to improve the properties of the 40H steel.