Manufacture of Two-layers and Double-sided Iron Castings with Differential Structure and Properties

The paper proposes a new method of production of bilayer and double-sided castings with differentiated structure and properties using the technology of in-mold modification of the initial melt, smelted in a single melting furnace, which ensures formation of hard wear-resistant white iron as the working layer, and formation of ductile shock-resistant cast iron with nodular graphite as the core or the mounting part. Numerous laboratory studies confirm the feasibility of the proposed method and provide conditions ensuring differentiation of structure and properties in local parts or layers of castings. The prospects of the method for manufacturing a wide range of industrial castings are indicated

Investigation of the thermophysical properties of high-melting materials with the aid of a complex of instruments

The evaporation rate, vapor pressure, heats of evaporation reaction (sublimation, dissociation), enthalpy, electrical resistance, heat capacity, emissivity, and heat conductivity of various carbides, borides, sulfides, nitrides, selenides, and phosphides were investigated. A set of high temperature high vacuum devices, calorimeters (designed for operation at 400 to 1300 K and from 1200 K), and mass spectrometers, most of which were specially developed for these studies, is described

Лікування післяпункційного головного болю

Післяпункційний головний біль може ускладнитись порушеннями слуху чи зору, внутрішньочерепною субдуральною чи інтрацеребральною гематомою, ущемленням головного мозку і смертю. Тому кожен випадок післяпункційного головного болю потребує серйозного ставлення. Сучасні неінвазивні способи лікування післяпункційного головного болю: ліжковий режим, рідини, кофеїн, суматриптан, – малоефективні. Хірургічне закриття розриву твердої оболони є методом останньої надії. Епідуральне пломбування кров’ю лишається інвазивним методом вибору, з приблизно 70 % тривалого успіху після першої ін’єкції. Старовинна внутрішньовенна акватерапія є менш інвазивною і доволі популярною серед українських акушерських анестезіологів. Блокада крило-піднебінного вузла є найменш інвазивним методом, що потребує дослідження

Multi-Spark Plasma Actuator for Flow Control

Plasma properties of spark discharge at multi-electrode actuator, designed for flow control, are discussed. Optical emission spectroscopy is used in investigation of such plasma. No effect of metal particles eroded from electrodes on properties of spark discharge plasma was observed. A method of excitation temperature determination by reconstructing of experimentally registered spectrum of the spark was developed

X-ray Diffraction Study of the NaF – LiF – LnF3 (Ln=La,Nd) Eutectic Composition in the Liquid and Solid States

The ternary eutectic alloy with the composition 33 mol % NaF+53 mol % LiF+14 mol % NdF3 has been studied in the liquid and solid states using differential thermal analysis and X-ray diffraction at room and high temperatures. The obtained results demonstrate that the eutectic alloy undergoes no phase transformations at temperatures from 298 K to melting point. Analysis of RMC models of the melt indicates that there is no dense non-crystalline packing of the fluorine anions in contrast to the eutectic NaF—LiF—LaF3 melt

Methods of Research of Shape Memory Effect and Superelasticity in the Alloy Ti-22%Nb-6%Zr

Cyclic tensile tests were carried out as applied to annealed foils of the superelastic Ti-22Nb-6Zr alloy (at.%) as well as indentation of these foils with an increasing amplitude of indenter intrusion in the sample at temperatures lowering from 20∘ down to -60-70∘C. Mechanical tests were performed on samples cut along andacross the rolling direction. According to the results of measurements of mechanical properties, it is established that during cyclic stretching of foils in the rolling direction, superelasticity manifests itself, and also material training is observed with subsequent preservation of the maximal renewable deformation. When the foil is loaded in the transverse direction, no superelasticity is observed, moreover, some samplesare destroyed even with a deformation of 2%. With a decrease in the annealing temperature of foils, the curve of the continuous change of loading with the depth of indenter penetration undergoes substantial changes, which indicate the appearance of a superelastic deformation under the indenter. Curves of monotonic loading and discharge undergo an inflection, and the plastic deformation region is substantially reduced. From the discharge curves in this case, we can calculate two elastic modules, typical for the usual elasticity and superelastic behavior of the alloy. In general, the main characteristics of the continuous indentation curve depend on the amount of the martensitic phase. The dependence of the modules of elasticity for foils, coolingdown to -(60-70∘C), and for their subsequent heating up to the room temperature is constructed

Features of Formation of Crystallographic Texture in Cells of Spacing Grid at their Stamping

The structural and textural heterogeneity of thin-walled tubes of Zr-1% Nb alloy used for stamping of the cells of the spacing grid (SG) was studied. It was found, that structure and texture of thin-walled tubes corresponds to incomplete recrystallization. During the increasing of recrystallization degree, the variation of crystal structure parameters of Nb solid solution i