113 research outputs found
Stability analysis of dynamical regimes in nonlinear systems with discrete symmetries
We present a theorem that allows to simplify linear stability analysis of
periodic and quasiperiodic nonlinear regimes in N-particle mechanical systems
(both conservative and dissipative) with different kinds of discrete symmetry.
This theorem suggests a decomposition of the linearized system arising in the
standard stability analysis into a number of subsystems whose dimensions can be
considerably less than that of the full system. As an example of such
simplification, we discuss the stability of bushes of modes (invariant
manifolds) for the Fermi-Pasta-Ulam chains and prove another theorem about the
maximal dimension of the above mentioned subsystems
Magnetoelectric effect due to local noncentrosymmetry
Magnetoelectrics often possess ions located in noncentrosymmetric
surroundings. Based on this fact we suggest a microscopic model of
magnetoelectric interaction and show that the spin-orbit coupling leads to
spin-dependent electric dipole moments of the electron orbitals of these ions,
which results in non-vanishing polarization for certain spin configurations.
The approach accounts for the macroscopic symmetry of the unit cell and is
valid both for commensurate and complex incommensurate magnetic structures. The
model is illustrated by the examples of MnWO4, MnPS3 and LiNiPO4. Application
to other magnetoelectrics is discussed.Comment: 11 pages, 2 figures, 2 table
Research on the improvement of mixed titania and Co(Mn) oxide nano-composite coatings
The structure and the properties of the oxide films formed on titanium in the diphosphate based electrolytes by means of plasma electrolytic oxidizing at direct current density of 2-2.5 AΒ·dmβ»Β² have been studied. Oxide layers of different composition and content of alloying elements were obtained by modification of electrolytes and variation in current density. The interelectrode voltage during PEO, chemical and phase composition, topography and microstructure of the formed layers depend on the electrolyte composition and applied current density. The spark-discharge regime was shown to be reached at inter-electrode voltage 100 to 130 V depending on the composition of electrolyte. The effect of chemical composition and surface morphology formed mixed oxide films on the corrosion resistance and catalytic activity has been discussed
ΠΠ°Π»ΡΠ²Π°Π½ΠΎΡ ΡΠΌΡΡΠ½Π΅ ΡΠΎΡΠΌΡΠ²Π°Π½Π½Ρ Π±Π°Π³Π°ΡΠΎΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠ½ΠΎΠ³ΠΎ ΡΠΏΠ»Π°Π²Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Ρ ΠΊΠΎΠ±Π°Π»ΡΡΠ° ΡΠ° ΡΡΠ³ΠΎΠΏΠ»Π°Π²ΠΊΠΈΡ ΠΌΠ΅ΡΠ°Π»ΡΠ²
Effects of major parameters of electrolysis on the composition and morphology of the cobalt-molybdenum-tungsten alloy from citrate- pyrophosphate and citrate-ammonium electrolytes have been analysed. It has been shown that the content of component metals in the Co-W-Mo alloy depends on the nature and composition of the electrolyte solution. The influence of electrolysis conditions and regime on the structure and morphology of cobalt alloys with refractory metals has been established. The elemental composition and morphology of the triple cobalt - molybdenum - tungsten coatings have been determined with a scanning electron microscope.ΠΡΠΎΠ°Π½Π°Π»ΡΠ·ΠΎΠ²Π°Π½ΠΎ Π²ΠΏΠ»ΠΈΠ² ΠΎΡΠ½ΠΎΠ²Π½ΠΈΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡΠ² Π΅Π»Π΅ΠΊΡΡΠΎΠ»ΡΠ·Ρ Π½Π° ΡΠΊΠ»Π°Π΄ ΡΠ° ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΡΡ ΡΠΏΠ»Π°Π²Ρ ΠΊΠΎΠ±Π°Π»ΡΡ-ΠΌΠΎΠ»ΡΠ±Π΄Π΅Π½-Π²ΠΎΠ»ΡΡΡΠ°ΠΌ ΠΎΡΡΠΈΠΌΠ°Π½ΠΎΠ³ΠΎ Π· ΡΠΈΡΡΠ°ΡΠ½ΠΎ-Π΄ΠΈΡΠΎΡΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΡΠ° ΡΠΈΡΡΠ°ΡΠ½ΠΎ-Π°ΠΌΠΎΠ½ΡΠ°ΡΠ½ΠΎΠ³ΠΎ Π΅Π»Π΅ΠΊΡΡΠΎΠ»ΡΡΡΠ². ΠΠ° Π΄ΠΎΠΏΠΎΠΌΠΎΠ³ΠΎΡ ΡΠΊΠ°Π½ΡΠ²Π½ΠΎΠ³ΠΎ Π΅Π»Π΅ΠΊΡΡΠΎΠ½Π½ΠΎΠ³ΠΎ ΠΌΡΠΊΡΠΎΡΠΊΠΎΠΏΡ Π΄ΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½ΠΎ ΡΠΊΠ»Π°Π΄ Ρ ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΡΡ ΠΏΠΎΡΡΡΠΉΠ½ΠΈΡ
ΠΏΠΎΠΊΡΠΈΡΡΡΠ². ΠΡΠ»ΠΎ ΠΏΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΠΎ Π²ΠΌΡΡΡ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΡΠ² Π² ΡΠΏΠ»Π°Π²Ρ Π‘ΠΎ-W-ΠΠΎ Π·Π°Π»Π΅ΠΆΠΈΡΡ Π²ΡΠ΄ ΠΏΡΠΈΡΠΎΠ΄ΠΈ Π»ΡΠ³Π°Π½Π΄Π° Ρ ΡΠΏΡΠ²Π²ΡΠ΄Π½ΠΎΡΠ΅Π½Π½Ρ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΡΠΉ ΡΠΏΠ»Π°Π²ΠΎΡΠ²ΡΡΠ½ΠΈΡ
ΠΌΠ΅ΡΠ°Π»ΡΠ². ΠΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ Π²ΠΏΠ»ΠΈΠ² Π³ΡΡΡΠΈΠ½ΠΈ ΡΡΡΡΠΌΡ, Π° ΡΠ°ΠΊΠΎΠΆ ΡΠ°ΡΡ ΡΠΌΠΏΡΠ»ΡΡΡ ΡΠ° ΠΏΠ°ΡΠ·ΠΈ Π½Π° ΡΡΡΡΠΊΡΡΡΡ Ρ ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΡΡ ΠΏΠΎΠΊΡΠΈΡΡΡΠ²
Π€ΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΠΎΠΊΡΡΡΠΈΠΉ ΡΠΌΠ΅ΡΠ°Π½Π½ΡΠΌΠΈ ΠΎΠΊΡΠΈΠ΄Π°ΠΌΠΈ Π°Π»ΡΠΌΠΈΠ½ΠΈΡ ΠΈ ΠΌΠ°ΡΠ³Π°Π½ΡΠ° Π½Π° ΡΠΏΠ»Π°Π²Π΅ ΠΠ25
Features of plasma electrolytic oxidation of the AL25 cast complex-alloyed aluminum alloy are discussed. It has been shown that a variation in the nature and concentration ratio of the electrolyte components provides the formation of mixed-oxide coatings containing the materials of the basic matrix and the dopant. An increase in the coating thickness and the manganese oxide content in the coating is achieved by the homogenization of the treated surface owing to the simultaneous formation of oxides and the removal of alloying components of the alloy from the surface layers. Current density intervals that provide a uniform distribution of elements in the coating and a high efficiency of the Faraday and thermochemical reactions are determined. It is found that the stoichiometric oxygen index in MnOx oxides is x = 1.71β1.87. Testing of the synthesized oxide systems in the model oxidation of carbon (II) oxide to COβ shows that the ignition and complete conversion temperatures are at the level of values characteristic of platinum catalysts.Π Π°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΠΏΠ»Π°Π·ΠΌΠ΅Π½Π½ΠΎ-ΡΠ»Π΅ΠΊΡΡΠΎΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΎΠΊΡΠΈΠ΄ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π»ΠΈΡΠ΅ΠΉΠ½ΠΎΠ³ΠΎ ΡΠ»ΠΎΠΆΠ½ΠΎΠ»Π΅Π³ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠΏΠ»Π°Π²Π° Π°Π»ΡΠΌΠΈΠ½ΠΈΡ ΠΠ25. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Π²Π°ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠΈΡΠΎΠ΄Ρ ΠΈ ΡΠΎΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΉ ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠΎΠ² ΡΠ»Π΅ΠΊΡΡΠΎΠ»ΠΈΡΠ° ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°ΡΡ ΠΏΠΎΠΊΡΡΡΠΈΡ ΡΠΌΠ΅ΡΠ°Π½Π½ΡΠΌΠΈ ΠΎΠΊΡΠΈΠ΄Π°ΠΌΠΈ, Π² ΡΠΎΡΡΠ°Π² ΠΊΠΎΡΠΎΡΡΡ
Π²Ρ
ΠΎΠ΄ΠΈΡ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π» ΠΎΡΠ½ΠΎΠ²Π½ΠΎΠΉ ΠΌΠ°ΡΡΠΈΡΡ ΠΈ Π΄ΠΎΠΏΠ°Π½ΡΠ°. ΠΠΎΠ²ΡΡΠ΅Π½ΠΈΠ΅ ΡΠΎΠ»ΡΠΈΠ½Ρ ΠΏΠΎΠΊΡΡΡΠΈΡ ΠΈ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΡ Π² Π½Π΅ΠΌ ΠΎΠΊΡΠΈΠ΄Π° ΠΌΠ°ΡΠ³Π°Π½ΡΠ° Π΄ΠΎΡΡΠΈΠ³Π°Π΅ΡΡΡ Π³ΠΎΠΌΠΎΠ³Π΅Π½ΠΈΠ·Π°ΡΠΈΠ΅ΠΉ ΠΎΠ±ΡΠ°Π±Π°ΡΡΠ²Π°Π΅ΠΌΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ Π·Π° ΡΡΠ΅Ρ ΠΎΠ΄Π½ΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΎΠΊΡΠΈΠ΄ΠΎΠ² ΠΈ ΡΠ΄Π°Π»Π΅Π½ΠΈΡ Π»Π΅Π³ΠΈΡΡΡΡΠΈΡ
ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½ΡΠΎΠ² ΡΠΏΠ»Π°Π²Π° ΠΈΠ· ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΡΡ
ΡΠ»ΠΎΠ΅Π². Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»Ρ ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΡΠΎΠΊΠ°, ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΠ²Π°ΡΡΠΈΠ΅ ΡΠ°Π²Π½ΠΎΠΌΠ΅ΡΠ½ΠΎΠ΅ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² Π² ΠΏΠΎΠΊΡΡΡΠΈΠΈ ΠΈ Π²ΡΡΠΎΠΊΡΡ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΠ°ΡΠ°Π΄Π΅Π΅Π²ΡΠΊΠΈΡ
ΠΈ ΡΠ΅ΡΠΌΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ΅Π°ΠΊΡΠΈΠΉ. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΡΡΠ΅Ρ
ΠΈΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΈΠ½Π΄Π΅ΠΊΡ ΠΏΠΎ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Ρ Π² ΠΎΠΊΡΠΈΠ΄Π°Ρ
MnOx ΡΠΎΡΡΠ°Π²Π»ΡΠ΅Ρ x = 1,71β1,87. Π’Π΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΎΠΊΡΠΈΠ΄Π½ΡΡ
ΡΠΈΡΡΠ΅ΠΌ Π² ΠΌΠΎΠ΄Π΅Π»ΡΠ½ΠΎΠΉ ΡΠ΅Π°ΠΊΡΠΈΠΈ ΠΎΠΊΠΈΡΠ»Π΅Π½ΠΈΡ ΠΎΠΊΡΠΈΠ΄Π° ΡΠ³Π»Π΅ΡΠΎΠ΄Π° (II) Π΄ΠΎ COβ ΠΏΠΎΠΊΠ°Π·Π°Π»ΠΎ, ΡΡΠΎ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ° Π·Π°ΠΆΠΈΠ³Π°Π½ΠΈΡ ΠΈ ΠΏΠΎΠ»Π½ΠΎΠΉ ΠΊΠΎΠ½Π²Π΅ΡΡΠΈΠΈ Π½Π°Ρ
ΠΎΠ΄ΠΈΡΡΡ Π½Π° ΡΡΠΎΠ²Π½Π΅ ΠΏΠ»Π°ΡΠΈΠ½ΠΎΠ²ΡΡ
ΠΊΠ°ΡΠ°Π»ΠΈΠ·Π°ΡΠΎΡΠΎΠ²
Electrodeposition of iron-molybdenum coatings from citrate electrolyte
Specifi c features of the electrodeposition of ironβmolybdenum coatings from a citrate electrolyte based on iron(III) sulfate and sodium molybdate in dc and unipolar pulsed modes were studied. It was demonstrated that bright compact coatings with varied content of molybdenum can be produced by varying the relative concentrations of salts of the alloy-forming components and the solution pH. The current density ranges providing the high efficiency of the galvanostastic electrolysis were determined and it was shown that using the pulsed mode makes smaller the amount of nonmetallic impurities in a coating, diminishes its roughness and leads to formation of surface layers with a more uniform composition, The ironβmolybdenum coatings exhibit a high corrosion resistance in corrosive media and physicomechanical properties improved as compared with the base metal, which makes it possible to recommend these coatings for protection from corrosive-mechanical disintegration and restoration of the surface of worn articles
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