Begell House Inc.
Nanoscience and Technology: An International Journal
NST
2572-4258
6
3
2015
A NEW MODEL FOR CONTACT INTERACTION BETWEEN AN ATOMIC FORCE MICROSCOPE PROBE AND A SAMPLE
179-191
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.10
N. I.
Uzhegova
Institute of Continuous Media Mechanics, Ural Branch of the Russian Academy of Sciences, Perm, Russian Federation
A. L.
Svistkov
Institute of Continuous Media Mechanics, Ural Branch of the Russian Academy
of Sciences, 1 Academician Korolev Ave., Perm, 614000, Russian Federation
nanocomposites
atomic force microscopy
force-distance curve
probe geometry
mechanical properties of material
contact interaction models
Hertz model
DMT model
JKR model
Polymer nanocomposites have found increasing use in various industries. The mechanical properties of these materials and their operational characteristics are directly dependent on the material structure at the nanoscale. In this context, investigation of filler−matrix interactions and their contribution to generation of the macroscopic properties of the material is the problem of current interest. An atomic force microscope (AFM) opened new possibilities for studying not only the structure of the material at the nanoscale and its local mechanical properties as well. The AFM images the topography of a sample surface by scanning the cantilever over the sample and yields a relationship between the applied load and the penetration depth. An understanding of this relationship requires special mathematical contact interaction models. The most common models for this purpose are the Derjaguin−Muller−Toporov (DMT) and Johnson−Kendall−Roberts (JKR) models. In both models the Hertz solution is used as a basis for the elastic component of contact interaction. However, in contrast to the Hertz model, they are able to take into account intermolecular interaction energy: the DMT model − out of the contact region, and the JKR model − within the contact region. A specific feature of the DMT model is that it does not allow one to evaluate how the probe moving away from the sample surface drags the material. The JKR model makes it possible to approximate experimental data in both cases, i.e., when the cantilever approaches and retracts the sample surface. However, it neglects the stiffness of the AFM cantilever, which should affect the accuracy of the calculation results. In the present paper, a new model for contact interaction between the AFM cantilever and the sample made of soft material is proposed. It takes into account the specific features of the elastic behavior of a cantilever by analyzing the value of probe lifting due to surface forces and by considering the probe as a rotational paraboloid.
EXPERIMENTAL INVESTIGATIONS OF MECHANICAL CHARACTERISTICS OF POWDER COATINGS ON AN EPOXY−POLYESTER SUBSTRATE BY NANOINDENTATION
193-202
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.20
A. G.
Getmanov
Moscow Aviation Institute, National Research University, 4 Volokolamskoe Highway, Moscow, 125993, Russia
Yu. V.
Kornev
Institute of Applied Mechanics, Russian Academy of Sciences, 7 Leningradsky Ave., Moscow, 125040, Russia
Mikhail Ivanovich
Martirosov
Moscow Aviation Institute, National Research University, 4 Volokolamskoe Highway, Moscow, 125993, Russia
Lev N.
Rabinskiy
Department of Engineering Education, Moscow Aviation Institute (National
Research University), 4 Volokolamskoe Highway, Moscow, 125080,
Russian Federation
epoxy-polyester coating
nanoindentation
mechanical characteristics
powder paints
modulus of elasticity
hardness
Berkovich indenter
spherical indenter
Nanoindentation of the surface of powder epoxy−polyester-based paint-and-lacquer coatings, deposited on a steel substrate, is described. The effect of the testing method on the identified mechanical properties is analyzed. The measurement results, obtained by a spherical indenter and a Berkovich indenter, are compared. The reduced modulus of elasticity, Young modulus, and hardness of the coatings are evaluated. The obtained experimental data demonstrate a substantial dependence of the determined mechanical properties of the powder coating on the type of the indenter. When a Berkovich indenter is used, the found Young modulus for coatings (0.6 GPa) is underrated in relation to the properties of the coatings, known from macro experiments (3 GPa). When a spherical indenter is used, the Young modulus is overrated (6.3 GPa).
THE EFFECTIVE LENGTH OF A NANOFILLER AND REINFORCEMENT DEGREE OF POLYMER/CARBON NANOTUBES (NANOFILAMENTS) NANOCOMPOSITES
203-208
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.30
Georgii V.
Kozlov
Kh. M. Berbekov Kabardino-Balkarian State University, 173 Chernyshevsky Str.,
Nal'chik, Kabardino-Balkarian Republic, 360004, Russia
Azha Ch.
Aygubova
FSBEI HE "Daghestan State Pedagogical University," Makhachkala, Republic of Dagestan, Russia
Yulia N.
Karnet
Institute of Applied Mechanics, Russian Academy of Sciences,7 Leningradsky Ave., Moscow, 125040, Russia
Gasan M.
Magomedov
FSBEI HE "Daghestan State Pedagogical University," Makhachkala,
Republic of Dagestan, Russia
nanocomposite
carbon nanotubes (nanofilaments)
anisotropy
ring-shaped structures
reinforcement degree
It has been shown that the reduction of the real anisotropy of carbon nanotubes (nanofilaments) in polymer nanocomposites on increase in the nanofiller content is due to the structural factor, namely, the formation of ring-shaped structures of the indicated nanofillers. The reduction of the anisotropy degree leads to a decrease in the reinforcement degree of polymer/carbon nanotubes (nanofilaments) nanocomposites.
SIMULATION OF HEAT AND MASS TRANSFER IN PORES AS APPLIED TO SYNTHESIS OF MAGNESIUM−ZINC AND NICKEL−ZINC FERRITE NANOPARTICLES
209-222
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.40
A. A.
Markov
A. Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences, 101/1 Vernadskii Ave, Moscow, 119526, Russia
M. A.
Hobosyan
Department of Physics, University of Texas at Rio Grande Valley, Brownsville, TX 78520, USA
K. S.
Martirosyan
Department of Physics, University of Texas at Rio Grande Valley, Brownsville, TX 78520, USA
carbon combustion
submicron-size tubes and pores
slip
jumps of temperature and concentrations
carbon combustion synthesis of oxides (CCSO)
Macroflows are considered for simulation of hot gas flow in a channel with nanopores. The flows are caused by the effects of gas slip, jumps of temperature and concentrations of gas mixture components on the surface of pores. The macroflows are obtained by averaging microflows in nanopores. The intensities of slip processes and jumps of temperature and concentrations are presented in dimensionless variables as functions of porosity, coefficients of gas molecules reflection from the surface of pores, and coefficients of thermal and concentration accommodation. Heat and mass transfer is calculated at various intensities of slip processes and jumps of temperature and concentrations. The model developed is applied to synthesis of magnesium−zinc and nickel−zinc ferrite nanoparticles. The results are compared with the experimental data. The model uses the experimentally determined activation energy and ignition temperature, the slip parameters and jumps of temperature and concentrations of gas phase components on the surface of pores at high Knudsen numbers. The results of calculation agree satisfactorily with the measured values of temperature. The theoretical model allows predicting the characteristics of the combustion wave at both large and small porosity of the sample in the case of surface combustion.
INFLUENCE OF MORPHOLOGY AND PHASE CONSTITUTION ON CREEP PROPERTIES OF LOW-CARBON MARTENSITIC STEEL
223-231
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.50
N. V.
Kolebina
N. E. Bauman Moscow State Technical University, 5 2nd Baumanskaya Str., Moscow, 105005, Russia
V. L.
Danilov
N. E. Bauman Moscow State Technical University, 5 2nd Baumanskaya Str., Moscow, 105005, Russia
low-carbon martensitic steel
creep
deformation
stress
In the recent years, thanks to the combination of high corrosion resistance, good weldability, and plasticity, low-carbon stainless steel has gained wide application in different industrial sectors. In order to optimize the process of manufacture of parts from these types of steel, its stress−strain state should be simulated. In the present work, an equation of state that describes the behavior of the material with account for the influence of the phase composition and morphology of the structure on creep properties has been suggested based on the experimental data for 03Kh13N4M steel. The mixture rule and a model of dispersion-hardened material were used to describe the behavior of multiphase material. The reliability of the selected equations was confirmed by agreement with the experimental data.
MODELING THE HEALING OF MICROCRACKS IN METAL STIMULATED BY A PULSED HIGH-ENERGY ELECTROMAGNETIC FIELD. PART I
233-249
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.60
Konstantin V.
Kukudzhanov
Institute for Problems in Mechanics, Russian Academy of Sciences, 101 Vernadsky Ave., bld. 1, Moscow, 119526, Russia; Moscow Institute of Physics and Technology, 9 Institutskiy Lane,
Dolgoprudny, Moscow Region, 141700, Russia
Alexander L.
Levitin
Institute for Problems in Mechanics, Russian Academy of Sciences, 101 Vernadsky Ave., bld. 1, Moscow, 119526, Russia
healing of microcracks
cracks arrest
interaction of microdefects
electroplasticity
high-energy electromagnetic fields
electropulsing treatment
localization
phase transformations
melting
evaporation
The processes occurring in metallic specimens under the impact of electric high-density current are considered. The electric and temperature fields and their influence on the phase transformation and stress−strain state in the vicinity of microdefects in the form of plane cracks are studied. A mathematical model of the effect of an electromagnetic field on the predamaged elastic-plastic material with an ordered system of defects is proposed. The model accounts for melting and evaporation of material and the dependence of its all physical and mechanical properties on temperature. The problem is solved by finite elements method with the use of an adaptive mesh on the basis of an arbitrar Euler−Lagrange method. The numerical modeling has shown that in the vicinity of microdefects a high-density current with large field gradients arises, which leads to intense local heating accompanied by thermal expansion and melting of the metal on the tips of the microcracks. This results in high compressive stresses in the vicinity of microcracks, intense plastic flow of the material and, as a consequence, in the clamping of microcrack sides, decrease in microcrack length, and in the ejection of the molten material into the crack. As a result, the microcrack is completely healed. The numerical results obtained by the proposed model agree with experiment.
HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF Co0.5Zn0.5Fe2O4 NANOMATERIAL AND EVALUATION OF ITS PHOTOCATALYTIC ACTIVITY UNDER VISIBLE-LIGHT IRRADIATION
251-262
10.1615/NanomechanicsSciTechnolIntJ.v6.i3.70
Adil
Raza
Department of Physics, University of Agriculture, Faisalabad 38040, Pakistan
Ahmed
Azam
Department of Physics, University of Agriculture, Faisalabad 38040, Pakistan
Muhammad Shahzad
Saeed
Department of Physics, University of Agriculture, Faisalabad 38040, Pakistan
Muhammad
Ahsan
Department of Physics, University of Agriculture, Faisalabad 38040, Pakistan
photocatalyst
hydrothermal
TBO
Cobalt−zinc ferrite (Co0.5Zn0.5Fe2O4) nanophotocatalyst has been synthesized via hydrothermal technique. XRD and SEM were used for characterization to check the structure, morphology, and formation of nanoparticles. An UV−Vis photospectrometer was also used to check the optical properties of these nanoparticles. Photocatalytic activity of cobalt-zinc ferrite (Co0.5Zn0.5Fe2O4) nanophotocatalyst under visible-light irradiation was checked by the degradation rate of toluidine blue O (TBO). Moreover, under visible-light irradiation, enhanced photocatalytic activity was exhibited by Co0.5Zn0.5Fe2O4 nanophotocatalyst in the degradation of TBO. The degradation rate of TBO using Co0.5Zn0.5Fe2O4 nanophotocatalyst was 94.3% in 2 h. Meanwhile the properties like magnetic property and intrinsic chemical stability are the advantages possessed by these as-synthesized Co0.5Zn0.5Fe2O4 nanophotocatalysts, so it can be presumed that they could play an effective role in the field of industrial photodegradation of organic pollutants.