https://www.elibrary.ru/title_about_new.asp?i
1605-8119
Materials physics and mechanics
21
3
2014
1-104
RAR
RUS
207-221
ITMO Univesity
V.G. Dubrovskii
St.Petersburg, Russia
St. Petersburg Academic University
Berdnikov
St.Petersburg, Russia
Size distributions and scaling in heterogeneous nucleation with size-linear rate constants
We present a theoretical analysis of rate equations for heterogeneous nucleation of nanomaterials with linear size dependences of the aggregation and fragmentation rate constants. Two scenarios are considered, one relating to stable growth and the other describing unstable situation with a time-dependent critical size. An interesting analytical solution is obtained which is exact in the stable case and only asymptotic in the unstable growth. This solution is expressed through the Polya distribution. Its continuum form features scaling properties for all but very small sizes, which is an intrinsic property of the model. Our scaled size distribution is capable of reproducing both monomodal and monotonically decreasing shapes depending on the value of the dimerization constant. The obtained solution is shown to reproduce fairly well some experimental size spectra of linear chains of metal adatoms on Si(100) surfaces.
nanomaterials; heterogeneous nucleation; rate equations
https://mpm.spbstu.ru/article/2014.37.1/
MPM321_01_dubrovskii.pdf
RAR
RUS
222-225
Institute for Problems of Mechanical Engineering of the RAS
Bratov
St.Petersburg, Russia
St.-Petersburg State University
Petrov
St.Petersburg, Russia
Erosion of asphalt as a result of automobile tire studs impacts
The main objective of the presented research is to develop a model in order to predict fracture of asphalt road surface impacted by an automobile tire stud. As a result of the analysis it is demonstrated that the critical automobile speed leading to creation of fracture in asphalt does depend on combination of asphalt mean elastic modulus and special dynamic strength characteristics responsible for the incubation process of microcracking caused by impacts. It is shown that in certain conditions smaller elastic moduli combined with bigger ductility of compound and increased dynamic strength can result in greater threshold car velocities giving brittle damage to asphalt. At the same time larger elastic moduli can provide better performance of asphalt layer undergoing quasistatic loading (slow heavy traffic). One of the practical solutions to maximize durability of highways is to use different asphalt mixtures in right (slower) and left (faster) traffic lanes. This can be, for example, achieved by addition of plasticizers into asphalt mixture used to cover high-speed traffic lanes. FEM simulation is giving a quantitative prediction of critical vehicle velocities leading to initiation of fracture in asphalt.
asphalt pavement; erosion; fracture; impact; tire stud; optimization; incubation process
https://mpm.spbstu.ru/article/2014.37.2/
MPM321_02_bratov.pdf
RAR
RUS
230-235
Institute of Problems of Mechanical Engineering RAS
Bulygin
St.Petersburg, Russia
Institute of Problems of Mechanical Engineering RAS
Aero
St.Petersburg, Russia
Institute of Problems of Mechanical Engineering, Russian Academy of Sciences
Korzhenevskii
St.Petersburg, Russia
Dynamic theory of coexisting austenite-martensite phase formation
A two-dimensional nonlinear lattice model of austenite-martensite transformation is considered. The model Hamiltonian contains a periodic term and gradient ones. The mixed gradient terms are included to account for the coupling of internal structural degrees of freedom of the complex lattice with the conventional acoustic displacements. The exact solutions that describe constant velocity growth and morphology of the coexisting incommensurate austenite-martensite structures are obtained. In particular, the results explain the appearance so called "premartensitic" superlattice reflections that are typically observed near the transformations.
austenite-martensite transformation; two-dimensional microstructures; nonlinear theory of microstructure formation; acoustic mode; pseudo-optical mode
https://mpm.spbstu.ru/article/2014.37.3/
MPM321_03_aero.pdf
RAR
RUS
242-247
ITMO Univesity
Bibik
St.Petersburg, Russia
ITMO University
Kolobkova
St.Petersburg, Russia
ITMO University
Ya.A. Nekrasova
St.Petersburg, Russia
ITMO University
Nikonorov
St.Petersburg, Russia
ITMO Univesity
Shvaleva
St.Petersburg, Russia
F-1445-2014
7202768874
0000-0003-3738-408X
ITMO University
Romanov
Alexey
alexey.romanov@niuitmo.ru
St.Petersburg, Russia
ITMO University
V.E. Bougrov
St.Petersburg, Russia
ITMO University
Aseev
St.Petersburg, Russia
ITMO Univesity
Tuzova
St.Petersburg, Russia
Inorganic composite "phosphor in glass" based on highly refractive LED-silicate matrix for white LEDs
Composite "phosphor-in-glass" based on high refractive index lead-silicate glass and YAG:Ce powder has been developed and synthesized. Glass composition optimization in the order to reduce scattering at glass/phosphor interfaces has been performed. Samples of composite light-converting materials for white LEDs were prepared by sintering glass powders and phosphor at 600 °С. Spectral, luminescent and structural properties of the obtained composites have been investigated. White LEDs based on the composite glass phosphor materials obtained have been tested. The color temperature of the probe LED was found to be 4370 K with the luminous efficacy 58 lm/W.
white LEDs; inorganic composite "phosphor-in-glass"; lead-silicate glass
https://mpm.spbstu.ru/article/2014.37.4/
MPM321_04_bibik.pdf
RAR
RUS
248-258
Institute of Problems of Mechanical Engineering RAS
I.A. Ovid’ko
И.А.
St.Petersburg, Russia
113263
6701854079
0000-0001-9909-2950
Institute of Problems of Mechanical Engineering RAS
Sheinerman
Alexander
St.Petersburg, Russia
Effect of twin boundary migration on fracture toughness of nano-twinned metals
A model is proposed that describes the effect of twin boundary migration in fracture toughness of nanotwinned solids. Within the model, twin boundary migration occurs under the action of high stress fields acting near the crack tip and is accompanied by the formation of the quadrupoles of wedge disclinations. It is shown that twin boundary migration hinders crack growth and thereby increases fracture toughness of nanotwinned solids.
nanotwinned metals; fracture; cracks
https://mpm.spbstu.ru/article/2014.37.5/
MPM321_05_ovidko.pdf
RAR
RUS
259-265
Lomonosov Moscow State University
Sviridova
Moscow, Russia
Ufa State Aviation Technical University
Salimgareeva
Ufa, Russia
Ufa State Aviation Technical University
Semenova
Ufa, Russia
Saint Petersburg State University
E.G. Zemtsova
St.Petersburg, Russia
Ufa State Aviation Technical University
Valiev
R.Z.
Ufa, Russia
Ufa State Aviation Technical University
D'jkonov
Ufa, Russia
Lomonosov Moscow State University
Stenina
Moscow, Russia
Requlation of the surface microrelief of coarse-grained and ultrafine-grained titanium by etching method
In this paper we study the surface modification of titanium Grade 4 by the method of chemical etching of titanium with coarse-grained (CG) and ultrafine-grained (UFG) structure. It is shown that the most homogeneous the surface micro relief is formed in samples with UMP structure after chemical etching in a solution of 30 % HNO3+3 % HF. The results of the study of the surface of titanium with CG and UFG structure after chemical etching indicate that fine-grained state more intensively subjected to etching. As the result, more homogeneous surface is formed.
titanium; grain; modification; surface etching; microrelief
https://mpm.spbstu.ru/article/2014.37.6/
MPM321_06_zemtsova.pdf
RAR
RUS
266-274
St. Petersburg State V.I. Ul’yanov (Lenin) Electrical Engineering University
Zubkova
St.Petersburg, Russia
Institute of Problems of Mechanical Engineering RAS
Osipov
A.V.
St.Petersburg, Russia
Ioffe Institute
Orlova
T.S.
St.Petersburg, Russia
Ioffe Institute
S.N. Rodin
St.Petersburg, Russia
P-4505-2016
7006034020
0000-0002-2973-8645
Institute of Problems of Mechanical Engineering RAS
Kukushkin
S.A.
sergey,a.kukushkin@gmail.com
St.Petersburg, Russia
Ioffe Institute
Bessolov
St.Petersburg, Russia
Ioffe Institute
Konenkova
St.Petersburg, Russia
The mechanism of formation of structural V-defects in polar and semipolar epitaxial GaN films synthesized on SiC/Si(111) and SiC/Si(100) heterostructures
The past results related to the main features of formation of structural V-defects in polar GaN(0001) and semi-polar epitaxial GaN films are presented. The GaN films have been synthesized by hydride-chloride vapor-phase epitaxy (HVPE) on two different substrates Si(111) and Si(100) with an intermediate nano-SiC epitaxial layer. The nano-SiC layer has been formed by a method of atom substitution on the Si substrate. The experimental studies have demonstrated that V-defects on the surface of GaN(0001) films are regular hexagons of 30 µm in size, while on the surface of GaN V-defects are of the order of 1 µm. It was found that V-defects on the semipolar face are extended along the (1123). direction. The size of oblique facets of V-defects on the surface of polar GaN(0001) is of about 1 µm, while on the surface of semipolar GaN (1101) layer they are much less, measuring about 150 nm, on the average. On the basis of thermodynamics, the mechanisms of nucleation of V-defects on polar and semipolar faces of GaN epitaxial films are elucidated, and the criteria of the formation of V-defects are theoretically derived. A good qualitative agreement between the experimental results and the theoretical model was found.
GaN films; semi-polar GaN; V-defects; etch pits; silicon carbide films; heterostructures; wide-band semiconductors; nanostructures
https://mpm.spbstu.ru/article/2014.37.7/
MPM321_07_bessolov.pdf
RAR
RUS
275-282
Institute for Problems of Mechanical Engineering of the RAS
Semenov
St.Petersburg, Russia
Peter the Great St. Petersburg Polytechnic University
Kochnev
St.Petersburg, Russia
Institute of Problems of Mechanical Engineering RAS
I.A. Ovid’ko
И.А.
St.Petersburg, Russia
Mechanical characteristics of graphene sheets containing high-density ensembles of 5-8-5 defects
Classical molecular dynamics is exploited to examine mechanical characteristics (ultimate tensile strength, and tensile strain-to-failure) of graphene sheets containing highdensity ensembles of 5-8-5 defects. Each such a defect represents a divacancy associated with "pentagon-octagon-pentagon" atomic configuration in hexagonal crystal lattice of graphene. We revealed that the ultimate tensile strength of graphene sheets significantly degrades (by tens of percent) due to the presence of 5-8-5 defects in graphene, as compared to the tensile strength of ideal (defect-free) graphene. Also, results of our computer model indicate that both the ultimate tensile strength and the tensile strain-to-failure of graphene sheets containing high-density ensembles of 5-8-5 defects are sensitive to temperature. In particular, when temperature increases, the ultimate strength decreases in the almost linear way, and the tensile strain-to-failure decreases in the way similar to linear one.
grapheme; strength; defects; fracture; cracks
https://mpm.spbstu.ru/article/2014.37.8/
MPM321_08_ovidko.pdf
RAR
RUS
283-287
ITMO Univesity
Serebryakova
St.Petersburg, Russia
ITMO University
V.E. Bougrov
St.Petersburg, Russia
F-1445-2014
7202768874
0000-0003-3738-408X
ITMO University
Romanov
Alexey
alexey.romanov@niuitmo.ru
St.Petersburg, Russia
ITMO Univesity
Kolodeznyi
St.Petersburg, Russia
ITMO University
Ivukin
St.Petersburg, Russia
Thermal analysis of phosphor containing silicone layer in high power LEDs
Efficacy of high power light emitting diodes (LEDs) strongly depends on their thermal management. Heat generated due to non-radiative recombination of carriers in LED active region and due to Stokes losses in phosphor material leads to temperature rise in the device interior and in the phosphor containing silicone layer (PCSL). High temperature in the PCSL influences its thermal quenching behavior and changes luminescence decay time. To achieve high LED efficacy, proper thermal control of PCSL is of the great importance. In this study, we build a thermal model of the LED with PCSL and perform numerical simulations to analyze the heat distribution in the layer. Numerical analysis shows that temperature of PCSL can reach 85 °C and more. At least 30 % temperature drop is demonstrated due to the thickness variation of silicone layer.
LED; phosphor containing silicone layer: thermal analysis
https://mpm.spbstu.ru/article/2014.37.9/
MPM321_09_kolodeznyi.pdf
RAR
RUS
288-298
Institute of Problems of Mechanical Engineering RAS
I.A. Ovid’ko
И.А.
St.Petersburg, Russia
7003559440
0000-0003-2192-0386
Institute for Problems of Mechanical Engineering RAS
Skiba
Nikolai
nikolay.skiba@gmail.com
St. Petersburg, Russia
Nucleation of Deformation Nanotwins at Grain Boundaries Containing Disclinations in Nanomaterials
A theoretical model is suggested which describes nucleation of nanoscale twins at locally distorted grain boundaries containing disclinations in nanocrystalline and ultrafinegrained materials. Within the model, nucleation of a nanotwin occurs through cooperative emission of partial dislocations from a grain boundary segment containing a disclination. We calculated the energy characteristics of the nanotwin nucleation process in question. Also, we revealed critical values of the external shear stress needed for realization of the nanotwin nucleation process in nanocrystalline and ultrafine-grained materials.
twins; grain boundaries; disclinations; deformation; nanomaterials
https://mpm.spbstu.ru/article/2014.37.10/
MPM321_10_ovidko.pdf
RAR
RUS
299-302
Institute for Problems of Mechanical Engineering of the RAS
Semenov
St.Petersburg, Russia
Finite-element Analysis of Deformation of Titanium Cylinder with a Ceramic Coating under Axial Compression
In the paper, a finite element analysis of the stress-deformation state of the titaniumcylinder with ceramic coating based on zirconium dioxide under axial compression is performed. Zones of tensile stress are identified, and an estimate of their concentration as a function of the applied load is obtained.
a titanium cylinder; the ceramic coating; an axial compression; a finite element analysis
https://mpm.spbstu.ru/article/2014.37.11/
MPM321_11_semenov.pdf
RAR
RUS
305-310
Peter the Great St. Petersburg Polytechnic University
Kurapova
St.Petersburg, Russia
Peter the Great St. Petersburg Polytechnic University
Novik
St.Petersburg, Russia
Scientific and Technical Center “Glass and Ceramics”
Archakov
St.Petersburg, Russia
Institute Silicate Chemistry of Russian Academy of Science
Konakov
V.G.
St.Petersburg, Russia
Institute of Problems of Mechanical Engineering RAS
I.A. Ovid’ko
И.А.
St.Petersburg, Russia
Usage of nanoceramic based on ZrO2 in fabrication of sources for magnetron sputtering
The paper reports the development of the approach providing the opportunity to fabricate nanoceramic sources based on yttrium stabilized zirconia (YSZ) for magnetron sputtering. The approach includes sol-gel reverse precipitation synthesis of nanosize YSZ precursor powders with further freeze-drying resulting in high precursor powder dispersity and low agglomeration level in a wide temperature range. The use of such precursor powders makes possible fabrication of YSZ ceramics free of inorganic binders; this ceramics meets the requirements for the magnetron sputtering source material.
nanoceramics; zirconium dioxide (zirconia); sol-gel method
https://mpm.spbstu.ru/article/2014.37.12/
MPM321_12_konakov.pdf