Raw materials. Metallurgy
About the possibility of hybrid method of separation perovskite concentrate components
L.G. Gerasimova, A.G. Artemenkov, A.I. Nikolaev, E.S. Shchukina, M.V. Maslova
The process of interaction of perovskite concentrate with nitric acid under atmospheric conditions and overpressure has been studied. High indicators of separation of components in the form of solid phase – hydrated precipitate of titanium and rare metals and liquid phase containing calcium, rare-earth metals and thorium were achieved. It is shown that their structure and composition of the obtained precursors depend on the mode of acid treatment, which is important for choosing the direction of their further processing to obtain final products. In particular, it was found that increased pressure in the reaction zone causes rutilization of hydrated precipitate and, therefore, its further processing to obtain titanium dioxide and rare metals is expedient to be carried out by chlorination.
Keywords: perovskite concentrate, acid processing, selective separation of components, hydrated oxides of titanium and rare metals, rare-earth precursor.
Reversible deformation of spring actuators made of NiTi alloy at constant external counteraction
A.A. Sharonov, D.E. Gusev, A.O. Snegirev
The patterns of shape change of cylindrical springs made of NiTi alloy are considered depending on the level of counteracting stresses and thermal cycling boundaries. It has been shown that stresses from 20 to 110 MPa cause a completely reversible change in the shape of the material, and at higher stresses the accumulation of unrecovered strain occurs. During thermal cycling, a decrease in heating temperatures in the range As - Af and an increase in cooling temperatures in the range Ms - Mf is accompanied by a decrease in the magnitude of the reversible deformation of the material.
Keywords: NiTi alloy, shape memory effect, springs, reversible deformation.
Investigation of the effect of hot isostatic pressing parameters on the structure and mechanical properties of a pseudo-β-titanium alloy
A.S. Oryschenko, V.P. Leonov, E.V. Chudakov, Yu.Yu. Malinkina, I.M. Khachaturyan, Yu.M. Markova, S.Yu. Kuznetsov, S.A. Osipov
The article presents the results of a study of the effect of hot isostatic pressing conditions on the structure and mechanical properties of a pseudo-β-titanium alloy. The conditions in the temperature range from 700 to 880°C, pressures of 100 and 140 MPa were studied at various temperatures and the influence of fractional composition (less than 50, 50–100, 100–150 and 50–140 μm) on the mechanical properties and microstructure of the samples was analyzed. The main differences in the properties of the samples obtained at different soaking time (4 and 6 hours) are also shown.
Keywords: hot isostatic process, pseudo-β-titanium alloy, metal powder, fractional composition, gas-stabilization parameters
Influence of vacuum ion-plasma nitriding on the corrosion resistance of titanium alloys in ringer’s solution with a reduced oxygen content
S.V. Skvortsova, Yu.V. Chernyshova, S.M. Sarychev, G.Yu. Nikolaev
The influence of the vacuum ion-plasma nitriding on the corrosion resistance of titanium alloys used for implantation in Ringer's solution with a reduced oxygen content was investigated. It was shown that the use of nitriding makes it possible to increase the corrosion resistance of titanium alloys in Ringer's solution under conditions of reduced oxygen content, as evidenced by an increase in the stationary potentials of the samples and a decrease in the current density of the passive region by almost an order of magnitude compared to the original samples under the same conditions.
Keywords: titanium alloys, medical implants, nitration, corrosion resistance.
The influence of vacuum annealing modes on the formation of homogeneous and gradient structures in a titanium alloy with a high aluminum content during thermal hydrogen treatment
A.A. Lidzhiev, A.M. Mamonov, A.V. Neiman, E.O. Agarkova, Yu.N. Kusakina
The patterns of formation of various structures in a titanium alloy with a high aluminum content during vacuum annealing, the final operation of thermal hydrogen treatment, have been established. It has been shown that at a vacuum annealing temperature of 950°C in an alloy with an initial hydrogen content of 0.4 wt. %, a gradient (α+β) structure is formed with a finely dispersed α-phase in the surface layer 2–4.5 mm deep and a coarse-plate α-phase in the core of cylindrical samples with a diameter of 18 mm. At lower temperature conditions, a structure homogeneous over the cross-section of the samples with a quasi-globular α-phase of varying degrees of dispersion is formed.
Keywords: titanium alloy, vacuum annealing, hydrogen, thermal hydrogen treatment, gradient structure.
Identification of titanium alloys
From the analysis of the known three series of studies on the technology of manufacturing products from PT-3V, VT20, VT5-1, VT14, VT35 alloys, an experimental and computational method for identifying titanium alloys with respect to their operational reliability is proposed. The method is developed on the basis of the hypothesis that when a continuous medium is deformed in the form of metals with a non-zero deformation rate, its shape change up to destruction obeys the mathematical model of a viscoplastic environment. The genome-forming matrix of the environment consisting of seven physically justified parameters and easy to define has been determined. Specific examples of the method's operability on experimental results.
Keywords: identification of metals, specific fracture work, dynamic viscosity coefficient, deformation rate, temperature, matrix.
Development of technology for manufacturing pipes from high-strength titanium alloys
T.A. Martynova, L.P. Rtishcheva, E.S. Evstigneeva, P.S. Krylov, D.A. Negodin, M.V. Lukin
The stages of development of technology for manufacturing pipes from high-strength titanium alloys are described.
Keywords: titanium alloys, cold-formed pipes, hot-formed pipes, production, high-strength titanium alloys, civil and military shipbuilding, nuclear energy.
Development of technology for the manufacture of critical titanium castings operating in aggressive environments under high pressure
M.N. Saubanov, I.O. Leushin, I.E. Illarionov
72 experimental melts were carried out in vacuum skull melting furnaces as part of experimental design and research work to ensure high mechanical properties of the titanium alloy.
The developed modified titanium alloy has a high strength while preserving the material with a tensile strength of at least 590 MPa and a relative elongation of at least 18%.
The work on the manufacture of body castings of gas valves and Christmas tree from a modified alloy operating under a pressure of 70 Mpa in an aggressive environment – with a high content of up to 25% hydrogen sulfide and carbon dioxide up to 15% is described.
Keywords: modified titanium alloy, vacuum skull melting furnaces, sulfide cracking, fountain fittings, high hardness layer, anti-corrosion tests.