[en] Methods are discussed to analyse both qualitatively and quantitatively the physical contact formation depending upon a microprotrusion height in case of pressure welding. For this purpose VT14 two-phase titanium alloy and in some cases OT4 alloy (for comparison) have been used. Those alloys are of a fine-grained polyhedral structure with a grain size of 8-10 μm for OT4 alloy and 2-3 μm for VT14 alloy. The tests have been performed with round specimens with a dia. of 16 mm and a height of 30 mm. The contact surface of one of the samples has been polished, that of the other one had triangular notched microprotrusions with a constant angle β equalling 15 deg and a pitch varying in different samples. The specimens have been butt-welded. The surface of the contact formed has been assessed after a break-down of welded joints depending upon the imprint area of the specimen with a polished surface. An assessment of the physical contact surface as well as fractographic and metallographic studies of the break-down surface have been performed with MMI-2, MBS-2 and MIM-8 microscopes. The paper describes results of studies at a welding temperature of 850-950 deg C, with a duration of 20 min specific pressure of 0.2 kgf/sq.mm

[en] The effect is considered of the recrystallization annealing upon the structure and the mechanical properties of a plasma nichrome coating having the composition ''nichrome + substrate'' from 12Kh18N10T steel and of the surface preparation by sandblasting upon the adhesive strength σsub(ad). The recrystallization annealing in vacuum (10^-2 mm Hg) at the temperature of 1000 deg C raises the tensile strength by 20-35 %. The highest adhesive strength is achieved by treating the surface of the steel with a coarse (800 to 1000 μm) SiC powder

No abstract available

[en] Structural changes in the VT22 alloy at temperature variations in the 800-1050 deg C and 550-700 deg C ranges as well as a possibility of structure differentiating after different regimes of heat treatment and superheating of articles were investigated. Deflection from the optimum heating temperature is shown to change character of β-matrix decomposition that manifests in different etching ability of the structure due to variation of dispersity and quantity of α-phase. A conclusion is made on the possibility of using light microscopy for control of heat treatment quality and for disclosing reasons for deflection of structural state from the optimum one

[en] Results of physicochemical properties measurement for flux compositions 55%CaF₂, 5%Al₂O₃Na₂O, 35-32%(MgO+SiO₂) -density, electric conductivity and viscosity, surface and interphase tension are presented. Temperature dependences of the properties are analyzed. Results of electroslag remelting of nickel (NP-2 grade) in mobile crystallizer for ingot diameter 105 mm are presented. The process of remelting is stable, magnesium melting loss decreases two times, ingot quality meats the standard requirements

[en] It is shown that the formation of thick (2 mm) plasma coatings is affected by the physicochemical properties of the substrate material as well as by spraying-process parameters. Unlike thin (0.1-0.2 mm) plasma coatings, in the formation of which the thermal action of the plasma jet and particles is of short duration, thick coatings are formed under conditions of prolonged thermal action. As a result of this, in the case of a titanium alloy substrate partial recrystallization of the tungsten in the vicinity of the substrate and more intense spreading of drops sprayed from a distance as large as 175 mm are observed. These circumstances, combined with a growing amount of oxides, adversely affect the strength characteristics of coatings. Electron probe microanalyses revealed the following: In the titanium-tungsten transition zone is formed a substitution solid solution of variable tungsten concentration; under these conditions the coating becomes the most vulnerable zone in mechanical shear testing. In the case of a bronze substrate the adhesion of a tungsten coating is determined chiefly by mechanical interlocking between the coating and the substrate. The character of formation of thick plasma coatings explains the fundamental difference in shear rupture behavior between titanium and bronze substrate specimens coated with tungsten

[en] Information has been obtained concerning the dependence of the antiradiation effect on chemical structure, particularly on the substitute in the β position of the alkyl chain of tryptamine. The example of the indole analog of adrenalin was used to confirm the previously observed fact that introducing a hydroxyl group in this position enhances the radioprotective effect of a compound

[en] Investigated is the effect of the initial structure (macrogranular, laminated, fibrous, recrystallized-fine-grain polyhedral) of VT5 alloy on high-temperature creep during compression. The process kinetics is studied. It is stated that the creep rate of the alloy with macrogranular structure is in an order lower, than with fibrous and recrystallized, which is, probably connected with the effect of grain size of intragranular structure, as well as with the state of grain boundaries