Nanomaterials

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2 pages, 165 KiB

Open AccessEditorial

Advances in Micro- and Nanomechanics

by Victor A. Eremeyev

Nanomaterials 2022, 12(24), 4433; https://doi.org/10.3390/nano12244433 - 13 Dec 2022

Cited by 1 | Viewed by 1273

Abstract

Recent advances in technologies of design, manufacturing and further studies of new materials and structures result in an essential extension of classic models of continuum and structural mechanics [...] Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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21 pages, 4791 KiB

Open AccessArticle

Strain-Gradient Bar-Elastic Substrate Model with Surface-Energy Effect: Virtual-Force Approach

by Suchart Limkatanyu, Worathep Sae-Long, Hamid Mohammad-Sedighi, Jaroon Rungamornrat, Piti Sukontasukkul, Woraphot Prachasaree and Thanongsak Imjai

Nanomaterials 2022, 12(3), 375; https://doi.org/10.3390/nano12030375 - 24 Jan 2022

Cited by 6 | Viewed by 2658

Abstract

This paper presents an alternative approach to formulating a rational bar-elastic substrate model with inclusion of small-scale and surface-energy effects. The thermodynamics-based strain gradient model is utilized to account for the small-scale effect (nonlocality) of the bar-bulk material while the Gurtin–Murdoch surface theory [...] Read more.

This paper presents an alternative approach to formulating a rational bar-elastic substrate model with inclusion of small-scale and surface-energy effects. The thermodynamics-based strain gradient model is utilized to account for the small-scale effect (nonlocality) of the bar-bulk material while the Gurtin–Murdoch surface theory is adopted to capture the surface-energy effect. To consider the bar-surrounding substrate interactive mechanism, the Winkler foundation model is called for. The governing differential compatibility equation as well as the consistent end-boundary compatibility conditions are revealed using the virtual force principle and form the core of the model formulation. Within the framework of the virtual force principle, the axial force field serves as the fundamental solution to the governing differential compatibility equation. The problem of a nanowire embedded in an elastic substrate medium is employed as a numerical example to show the accuracy of the proposed bar-elastic substrate model and advantage over its counterpart displacement model. The influences of material nonlocality on both global and local responses are thoroughly discussed in this example. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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18 pages, 3132 KiB

Open AccessArticle

Estimation of the Young’s Modulus of Nanometer-Thick Films Using Residual Stress-Driven Bilayer Cantilevers

by Luis A. Velosa-Moncada, Jean-Pierre Raskin, Luz Antonio Aguilera-Cortés, Francisco López-Huerta and Agustín L. Herrera-May

Nanomaterials 2022, 12(2), 265; https://doi.org/10.3390/nano12020265 - 14 Jan 2022

Cited by 2 | Viewed by 2642

Abstract

Precise prediction of mechanical behavior of thin films at the nanoscale requires techniques that consider size effects and fabrication-related issues. Here, we propose a test methodology to estimate the Young’s modulus of nanometer-thick films using micromachined bilayer cantilevers. The bilayer cantilevers which comprise [...] Read more.

Precise prediction of mechanical behavior of thin films at the nanoscale requires techniques that consider size effects and fabrication-related issues. Here, we propose a test methodology to estimate the Young’s modulus of nanometer-thick films using micromachined bilayer cantilevers. The bilayer cantilevers which comprise a well-known reference layer and a tested film deflect due to the relief of the residual stresses generated during the fabrication process. The mechanical relationship between the measured residual stresses and the corresponding deflections was used to characterize the tested film. Residual stresses and deflections were related using analytical and finite element models that consider intrinsic stress gradients and the use of adherence layers. The proposed methodology was applied to low pressure chemical vapor deposited silicon nitride tested films with thicknesses ranging from 46 nm to 288 nm. The estimated Young’s modulus values varying between 213.9 GPa and 288.3 GPa were consistent with nanoindentation and alternative residual stress-driven techniques. In addition, the dependence of the results on the thickness and the intrinsic stress gradient of the materials was confirmed. The proposed methodology is simple and can be used to characterize diverse materials deposited under different fabrication conditions. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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17 pages, 5505 KiB

Open AccessArticle

Nanomechanical and Nanotribological Properties of Nanostructured Coatings of Tantalum and Its Compounds on Steel Substrates

by Galina Melnikova, Tatyana Kuznetsova, Vasilina Lapitskaya, Agata Petrovskaya, Sergei Chizhik, Anna Zykova, Vladimir Safonov, Sergei Aizikovich, Evgeniy Sadyrin, Weifu Sun and Stanislav Yakovin

Nanomaterials 2021, 11(9), 2407; https://doi.org/10.3390/nano11092407 - 15 Sep 2021

Cited by 13 | Viewed by 2919

Abstract

The present paper addresses the problem of identification of microstructural, nanomechanical, and tribological properties of thin films of tantalum (Ta) and its compounds deposited on stainless steel substrates by direct current magnetron sputtering. The compositions of the obtained nanostructured films were determined by [...] Read more.

The present paper addresses the problem of identification of microstructural, nanomechanical, and tribological properties of thin films of tantalum (Ta) and its compounds deposited on stainless steel substrates by direct current magnetron sputtering. The compositions of the obtained nanostructured films were determined by energy dispersive spectroscopy. Surface morphology was investigated using atomic force microscopy (AFM). The coatings were found to be homogeneous and have low roughness values (<10 nm). The values of microhardness and elastic modulus were obtained by means of nanoindentation. Elastic modulus values for all the coatings remained unchanged with different atomic percentage of tantalum in the films. The values of microhardness of the tantalum films were increased after incorporation of the oxygen and nitrogen atoms into the crystal lattice of the coatings. The coefficient of friction, CoF, was determined by the AFM method in the “sliding” and “plowing” modes. Deposition of the coatings on the substrates led to a decrease of CoF for the coating-substrate system compared to the substrates; thus, the final product utilizing such a coating will presumably have a longer service life. The tantalum nitride films were characterized by the smallest values of CoF and specific volumetric wear. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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14 pages, 5517 KiB

Open AccessArticle

Fracture and Embedment Behavior of Brittle Submicrometer Spherical Particles Fabricated by Pulsed Laser Melting in Liquid Using a Scanning Electron Microscope Nanoindenter

by Daizen Nakamura, Naoto Koshizaki, Nobuyuki Shishido, Shoji Kamiya and Yoshie Ishikawa

Nanomaterials 2021, 11(9), 2201; https://doi.org/10.3390/nano11092201 - 26 Aug 2021

Cited by 5 | Viewed by 1922

Abstract

Generally, hard ceramic carbide particles, such as B₄C and TiC, are angulated, and particle size control below the micrometer scale is difficult owing to their hardness. However, submicrometer particles (SMPs) with spherical shape can be experimentally fabricated, even for hard carbides, [...] Read more.

Generally, hard ceramic carbide particles, such as B₄C and TiC, are angulated, and particle size control below the micrometer scale is difficult owing to their hardness. However, submicrometer particles (SMPs) with spherical shape can be experimentally fabricated, even for hard carbides, via instantaneous pulsed laser heating of raw particles dispersed in a liquid (pulsed laser melting in liquid). The spherical shape of the particles is important for mechanical applications as it can directly transfer the mechanical force without any loss from one side to the other. To evaluate the potential of such particles for mechanical applications, SMPs were compressed on various substrates using a diamond tip in a scanning electron microscope. The mechanical behaviors of SMPs were then examined from the obtained load–displacement curves. Particles were fractured on hard substrates, such as SiC, and fracture strength was estimated to be in the GPa range, which is larger than their corresponding bulk bending strength and is 10–40% of their ideal strength, as calculated using the density-functional theory. Contrarily, particles can be embedded into soft substrates, such as Si and Al, and the local hardness of the substrate can be estimated from the load–displacement curves as a nanoscale Brinell hardness measurement. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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11 pages, 3521 KiB

Open AccessArticle

Properties of CrSi₂ Layers Obtained by Rapid Heat Treatment of Cr Film on Silicon

by Tatyana Kuznetsova, Vasilina Lapitskaya, Jaroslav Solovjov, Sergei Chizhik, Vladimir Pilipenko and Sergei Aizikovich

Nanomaterials 2021, 11(7), 1734; https://doi.org/10.3390/nano11071734 - 30 Jun 2021

Cited by 5 | Viewed by 2537

Abstract

The changes in the morphology and the electrophysical properties of the Cr/n-Si (111) structure depending on the rapid thermal treatment were considered in this study. The chromium films of about 30 nm thickness were deposited via magnetron sputtering. The rapid thermal treatment was [...] Read more.

The changes in the morphology and the electrophysical properties of the Cr/n-Si (111) structure depending on the rapid thermal treatment were considered in this study. The chromium films of about 30 nm thickness were deposited via magnetron sputtering. The rapid thermal treatment was performed by the irradiation of the substrate’s back side with the incoherent light flux of the quartz halogen lamps in nitrogen medium up to 200–550 °C. The surface morphology was investigated, including the grain size, the roughness parameters and the specific surface energy using atomic force microscopy. The resistivity value of the chromium films on silicon was determined by means of the four-probe method. It was established that at the temperatures of the rapid thermal treatment up to 350 °C one can observe re-crystallization of the chromium films with preservation of the fine grain morphology of the surface, accompanied by a reduction in the grain sizes, specific surface energy and the value of specific resistivity. At the temperatures of the rapid thermal treatment from 400 to 550 °C there originates the diffusion synthesis of the chromium disilicide CrSi₂ with the wave-like surface morphology, followed by an increase in the grain sizes, roughness parameters, the specific surface energy and the specific resistivity value. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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11 pages, 5184 KiB

Open AccessArticle

Non-Isothermal Decomposition as Efficient and Simple Synthesis Method of NiO/C Nanoparticles for Asymmetric Supercapacitors

by Daria Chernysheva, Ludmila Pudova, Yuri Popov, Nina Smirnova, Olga Maslova, Mathieu Allix, Aydar Rakhmatullin, Nikolay Leontyev, Andrey Nikolaev and Igor Leontyev

Nanomaterials 2021, 11(1), 187; https://doi.org/10.3390/nano11010187 - 13 Jan 2021

Cited by 13 | Viewed by 2614

Abstract

A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. [...] Read more.

A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. NiO/C nanocomposites are composed of spherical particles distributed over the carbon support surface. The average diameter of nickel oxide spheres increases with the NiO content and are estimated as 36, 50 and 205 nm for nanocomposites with 10, 50 and 80 wt% NiO concentrations, respectively. In turn, each NiO sphere contains several nickel oxide nanoparticles, whose average sizes are 7–8 nm. According to the tests performed using a three-electrode cell, specific capacitance (SC) of NiO/C nanocomposites increases from 200 to 400 F/g as the NiO content achieves a maximum of 60 wt% concentration, after which the SC decreases. The study of the NiO/C composite showing the highest SC in three- and two-electrode cells reveals that its SC remains almost unchanged while increasing the current density, and the sample demonstrates excellent cycling stability properties. Finally, NiO/C (60% NiO) composites are shown to be promising materials for charging quartz clocks with a power rating of 1.5 V (30 min). Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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18 pages, 538 KiB

Open AccessArticle

Critical Temperatures for Vibrations and Buckling of Magneto-Electro-Elastic Nonlocal Strain Gradient Plates

by Giovanni Tocci Monaco, Nicholas Fantuzzi, Francesco Fabbrocino and Raimondo Luciano

Nanomaterials 2021, 11(1), 87; https://doi.org/10.3390/nano11010087 - 3 Jan 2021

Cited by 46 | Viewed by 2844

Abstract

An analytical method is presented in this work for the linear vibrations and buckling of nano-plates in a hygro-thermal environment. Nonlinear von Kármán terms are included in the plate kinematics in order to consider the instability phenomena. Strain gradient nonlocal theory is considered [...] Read more.

An analytical method is presented in this work for the linear vibrations and buckling of nano-plates in a hygro-thermal environment. Nonlinear von Kármán terms are included in the plate kinematics in order to consider the instability phenomena. Strain gradient nonlocal theory is considered for its simplicity and applicability with respect to other nonlocal formulations which require more parameters in their analysis. Present nano-plates have a coupled magneto-electro-elastic constitutive equation in a hygro-thermal environment. Nano-scale effects on the vibrations and buckling behavior of magneto-electro-elastic plates is presented and hygro-thermal load outcomes are considered as well. In addition, critical temperatures for vibrations and buckling problems are analyzed and given for several nano-plate configurations. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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21 pages, 10014 KiB

Open AccessArticle

Effect of Metallic or Non-Metallic Element Addition on Surface Topography and Mechanical Properties of CrN Coatings

by Tatyana Kuznetsova, Vasilina Lapitskaya, Anastasiya Khabarava, Sergei Chizhik, Bogdan Warcholinski, Adam Gilewicz, Aleksander Kuprin, Sergei Aizikovich and Boris Mitrin

Nanomaterials 2020, 10(12), 2361; https://doi.org/10.3390/nano10122361 - 27 Nov 2020

Cited by 6 | Viewed by 2785

Abstract

Alteration of the phase composition of a coating and/or its surface topography can be achieved by changing the deposition technology and/or introducing additional elements into the coating. Investigation of the effect of the composition of CrN-based coatings (including AlCrN and CrON) on the [...] Read more.

Alteration of the phase composition of a coating and/or its surface topography can be achieved by changing the deposition technology and/or introducing additional elements into the coating. Investigation of the effect of the composition of CrN-based coatings (including AlCrN and CrON) on the microparticle height and volume, as well as the construction of correlations between the friction coefficient at the microscale and the geometry of microparticles, are the goals of this study. We use atomic force microscopy (AFM), which is the most effective method of investigation with nanometer resolution. By revealing the morphology, AFM allows one to determine the diameter of the particles, their heights and volumes and to identify different phases in the studied area by contrasted properties. The evaluation of the distribution of mechanical properties (modulus of elasticity E and microhardness H) on the surfaces of multiphase coatings with microparticles is carried out by using the nanoindentation method. It is found that the roughness decreases with an increase in the Al concentration in AlCrN. For the CrON coatings, the opposite effect is observed. Similar conclusions are valid for the size of the microparticles and their height for both types of coating. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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21 pages, 6102 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Improved Hardness and Thermal Stability of Nanocrystalline Nickel Electrodeposited with the Addition of Cysteine

by Tamás Kolonits, Zsolt Czigány, László Péter, Imre Bakonyi and Jenő Gubicza

Nanomaterials 2020, 10(11), 2254; https://doi.org/10.3390/nano10112254 - 13 Nov 2020

Cited by 5 | Viewed by 2403

Abstract

Experiments were conducted for the study of the effect of cysteine addition on the microstructure of nanocrystalline Ni films electrodeposited from a nickel sulfate-based bath. Furthermore, the thermal stability of the nanostructure of Ni layers processed with cysteine addition was also investigated. It [...] Read more.

Experiments were conducted for the study of the effect of cysteine addition on the microstructure of nanocrystalline Ni films electrodeposited from a nickel sulfate-based bath. Furthermore, the thermal stability of the nanostructure of Ni layers processed with cysteine addition was also investigated. It was found that with increasing cysteine content in the bath, the grain size decreased, while the dislocation density and the twin fault probability increased. Simultaneously, the hardness increased due to cysteine addition through various effects. Saturation in the microstructure and hardness was achieved at cysteine contents of 0.3–0.4 g/L. Moreover, the texture changed from (220) to (200) with increasing the concentration of cysteine. The hardness of the Ni films processed with the addition of 0.4 g/L cysteine (∼6800 MPa) was higher than the values obtained for other additives in the literature (<6000 MPa). This hardness was further enhanced to ∼8400 MPa when the Ni film was heated up to 500 K. It was revealed that the hardness remained as high as 6000 MPa even after heating up to 750 K, while for other additives, the hardness decreased below 3000 MPa at the same temperature. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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17 pages, 7668 KiB

Open AccessArticle

Characterization of Enamel and Dentine about a White Spot Lesion: Mechanical Properties, Mineral Density, Microstructure and Molecular Composition

by Evgeniy Sadyrin, Michael Swain, Boris Mitrin, Igor Rzhepakovsky, Andrey Nikolaev, Vladimir Irkha, Diana Yogina, Nikolay Lyanguzov, Stanislav Maksyukov and Sergei Aizikovich

Nanomaterials 2020, 10(9), 1889; https://doi.org/10.3390/nano10091889 - 21 Sep 2020

Cited by 45 | Viewed by 5397

Abstract

The study focuses on in vitro tracing of some fundamental changes that emerge in teeth at the initial stage of caries development using multiple approaches. The research was conducted on a mostly sound maxillary molar tooth but with a clearly visible natural proximal [...] Read more.

The study focuses on in vitro tracing of some fundamental changes that emerge in teeth at the initial stage of caries development using multiple approaches. The research was conducted on a mostly sound maxillary molar tooth but with a clearly visible natural proximal white spot lesion (WSL). Values of mineral density, reduced Young’s modulus, indentation hardness and creep as well as the molecular composition and surface microstructure of the WSL and bordering dentine area were studied. The results obtained were compared to those of sound enamel and dentine on the same tooth. A decrease of mechanical properties and mineral density both for the WSL and bordering dentine was detected in comparison to the sound counterparts, as well as increase of creep for the enamel WSL. Differences in molecular composition and surface microstructure (including the indenter impressions) were found and described. WSL induces a serious change in the state of not only the visually affected enamel but also surrounding visually intact enamel and dentine in its vicinity. The results provide the basis for future studies of efficacy of minimal invasive treatments of caries. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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22 pages, 3650 KiB

Open AccessArticle

On Nonlinear Bending Study of a Piezo-Flexomagnetic Nanobeam Based on an Analytical-Numerical Solution

by Mohammad Malikan and Victor A. Eremeyev

Nanomaterials 2020, 10(9), 1762; https://doi.org/10.3390/nano10091762 - 6 Sep 2020

Cited by 44 | Viewed by 3425

Abstract

Among various magneto-elastic phenomena, flexomagnetic (FM) coupling can be defined as a dependence between strain gradient and magnetic polarization and, contrariwise, elastic strain and magnetic field gradient. This feature is a higher-order one than piezomagnetic, which is the magnetic response to strain. At [...] Read more.

Among various magneto-elastic phenomena, flexomagnetic (FM) coupling can be defined as a dependence between strain gradient and magnetic polarization and, contrariwise, elastic strain and magnetic field gradient. This feature is a higher-order one than piezomagnetic, which is the magnetic response to strain. At the nanoscale, where large strain gradients are expected, the FM effect is significant and could be even dominant. In this article, we develop a model of a simultaneously coupled piezomagnetic–flexomagnetic nanosized Euler–Bernoulli beam and solve the corresponding problems. In order to evaluate the FM on the nanoscale, the well-known nonlocal model of strain gradient (NSGT) is implemented, by which the nanosize beam can be transferred into a continuum framework. To access the equations of nonlinear bending, we use the variational formulation. Converting the nonlinear system of differential equations into algebraic ones makes the solution simpler. This is performed by the Galerkin weighted residual method (GWRM) for three conditions of ends, that is to say clamp, free, and pinned (simply supported). Then, the system of nonlinear algebraic equations is solved on the basis of the Newton–Raphson iteration technique (NRT) which brings about numerical values of nonlinear deflections. We discovered that the FM effect causes the reduction in deflections in the piezo-flexomagnetic nanobeam. Full article

(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)

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