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Area Function for Nanoindentation at High Temperatures
Toshiro Okawa,
Ian Thomas Clark,
Katsuhiko Tashiro,
Hideo Honma,
Kazuhiro Yoshihara,
Osamu Takai
Issue:
Volume 8, Issue 6, November 2019
Pages:
98-102
Received:
7 October 2019
Accepted:
24 October 2019
Published:
31 October 2019
Abstract: It becomes important to measure mechanical properties of local area of materials because of downsizing of industrial materials, and the fracture of materials often starts at the nanoscale defects. Therefore, the measurement of hardness of the local area of materials is one of key technologies to develop new materials. Nanoindentation is the depth sensing indentation method and can measure the mechanical properties of nanoscale area of materials. The hardness of materials under the controlled environment like high temperature is a big issue in energy or environment industries. Therefore, it becomes important to measure high temperature mechanical properties of nanoscale area of materials by nanoindentation. However, the shape of indenter may change when an indenter contacts to the material surface at high temperatures, and the nanoindentation at high temperatures may lead to inaccuracy of measurements. Nanoindentation does not measure indented are directly but converts the indentation depth to the indented area by area function. In order to correctly convert the indentation depth to the indented area, it is necessary to derive the area function of indented area at high temperatures. In this report, the area function is proposed that considers the change of indenter shape during repeating contact at heated materials. By using this proposed area function, nanoindentation hardness and the reduced modulus of sapphire were obtained at 303K, 473K, 673K, 873K and 1073K successfully. The nanoindentation can be used at high temperatures, if this proposed area function is used.
Abstract: It becomes important to measure mechanical properties of local area of materials because of downsizing of industrial materials, and the fracture of materials often starts at the nanoscale defects. Therefore, the measurement of hardness of the local area of materials is one of key technologies to develop new materials. Nanoindentation is the depth s...
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Elastic Stress Analysis of St 37 and St 70 Steels with Finite Element Method
Semih Taskaya,
Bilgin Zengin,
Kursat Kaymaz,
Muzaffer Askin
Issue:
Volume 8, Issue 6, November 2019
Pages:
103-108
Received:
11 October 2019
Accepted:
22 October 2019
Published:
4 November 2019
Abstract: The basic logic in the finite element method is to simplify and solve a complex problem. In this method, the solution region is divided into a plurality of simple, small, connected, sub-regions called finite elements. In other words, the problem which is divided into parts connected by a plurality of joint points can be easily solved. St 37 and St 70 steels are materials used in the manufacturing of general building materials, produced by processing the hot-formed steel further through a cold drawing process. Ansys; is a computer aided engineering program where analysis and simulations can be performed in computer aided engineering studies. It enables effective studies in different disciplines such as mechanics, structural analysis, computational fluid dynamics and heat transfer. The finite element method, which enables the solution of complex engineering problems with controllable parts by simplifying, is a common and useful solution method used in many engineering applications. St and St 70 steels are modeled as three-dimensional I-beams 3 mm in thickness in Ansys program package in accordance with the finite element method. Finite element method helps simplifying complex engineering problems and solving them with controllable parts. Elastic stress analyses were performed in X, Y, Z axes by stabilizing the right and left supports of steel beams and applying a pressure of 100 MPa on the top flanges. It was observed in Ansys simulation analyses that elastic stress effect was higher in St 37 steel compared to St 70 steel.
Abstract: The basic logic in the finite element method is to simplify and solve a complex problem. In this method, the solution region is divided into a plurality of simple, small, connected, sub-regions called finite elements. In other words, the problem which is divided into parts connected by a plurality of joint points can be easily solved. St 37 and St ...
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Novel RGO-ZnWO4-Fe3O4 Electrodes Material for Energy Storage Device Applications
Mohamed Jaffer Sadiq,
Paruthimal Kalaignan
Issue:
Volume 8, Issue 6, November 2019
Pages:
109-113
Received:
13 November 2019
Accepted:
23 November 2019
Published:
2 December 2019
Abstract: As the global concerns in the development of human civilization, the scientific and technological issues of energy utilization and environment protection are currently facing challenges. Nowadays, enormous energy demands of the world are mainly met by the non-renewable and environmental unfriendly fossil fuels. To replace the conventional energy platform, a pursuit of renewable and clean energy sources and carriers, including hydrogen storage, lithium batteries, and supercapacitors. Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. Herein, we report novel RGO-ZnWO4-Fe3O4 electrodes material can be synthesized using one step microwave irradiation technique and reported as an electrode material for supercapacitors applications. The surface morphology, chemical composition and electronic structure of the RGO-ZnWO4-Fe3O4 electrodes were characterized using X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical performance of the RGO-ZnWO4-Fe3O4 electrodes has been investigated using cyclic voltammetry (CV) techniques. The result reveals that a specific capacitance of 480 F/g, an energy density of 15 Wh/kg and power density of 1719.5 W/kg is observed over RGO-ZnWO4-Fe3O4 electrodes materials. The cost effective electrodes materials of RGO-ZnWO4-Fe3O4 can be useful for future electrochemical energy storage device applications.
Abstract: As the global concerns in the development of human civilization, the scientific and technological issues of energy utilization and environment protection are currently facing challenges. Nowadays, enormous energy demands of the world are mainly met by the non-renewable and environmental unfriendly fossil fuels. To replace the conventional energy pl...
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Preparation and Properties of Biosorbents on the Base of Fruit Seed Shell
Kartel Mykola,
Galysh Vita,
Wang Bo,
Mukalo Yevgen,
Kozakevych Roman,
Nikolaichuk Alina
Issue:
Volume 8, Issue 6, November 2019
Pages:
114-119
Received:
19 August 2019
Published:
3 December 2019
Abstract: The process of obtaining of new biosorbents from apricot seed shells by oxidative-organosolvent processing in "acetic acid - hydrogen peroxide" medium has been studied. The structural and sorption properties of the materials obtained using physical and chemical methods were investigated. The effect of the reactants ratio in solution, as well as the duration of the modification process on the yield, content of cellulose, lignin, and mineral components and on sorption properties of the products was studied. The dependence between the mineral content and the adsorption pore volume was shown. The positive effect of hydrogen peroxide application in the process of modifying of plant waste on cellulose content was estimated. Increasing the duration of modification increases the contribution of oxidative transformation of lignin into soluble products and decreases the yield of the lignocelluloses’ materials. The regularities of sorption of marker of low molecular weight toxins and non-steroidal anti-inflammatory drugs on obtained products were investigated. It has been found that the highest sorption capacity of obtained lignocelluloses’ sorbents towards methylene blue and Sodium Diclofenac corresponds to the samples with polysaccharide content 60%. It has been also found that the sorption equilibrium occurs within 120 min of contact. The obtained results demonstrate the feasibility of application of such lignocelluloses’ carriers in the production of prolonged action drugs.
Abstract: The process of obtaining of new biosorbents from apricot seed shells by oxidative-organosolvent processing in "acetic acid - hydrogen peroxide" medium has been studied. The structural and sorption properties of the materials obtained using physical and chemical methods were investigated. The effect of the reactants ratio in solution, as well as the...
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“Semiconductor” Model of the “Polymer-CNTs” Composite Strengthening
Karachevtseva Liudmyla,
Kartel Mykola,
Wang Bo,
Lytvynenko Oleg,
Onyshchenko Volodymyr,
Sementsov Yurii,
Trachevskyi Viacheslav
Issue:
Volume 8, Issue 6, November 2019
Pages:
120-126
Received:
20 August 2019
Published:
3 December 2019
Abstract: We analyzed “semiconductor” model of the “polymer-CNTs” composite strengthening at 300 K and low (0.1-0.5) wt% CNTs concentration. Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. We investigated influence of vibration bonds on polymer crystallization and strengthening in composite films of polyethylenimine, polyamide, polypropylene and rubber with multiwall carbon nanotubes. IR absorbance maxima we evaluated after formation of composite “polyethylenimine-carbon nanotube” in the spectral area of the sp3 hybridization bonds at the frequency of primary amino groups of polyethylenimine. High IR absorption in the spectral area of sp3 hybridization bonds of polypropylene, polyamide-6 with carbon nanotubes is determined by γω(CН) and γω(CH2) vibrations. We measured IR reflectance maxima of composite “rubber-carbon nanotube” in the spectral area of CH valence and deformation vibrations. The IR peak dependence on the carbon nanotube content corresponds to 1D Gaussian curve for the diffusion equation in the electric field between electrons of nanotubes and protons in polymer according to “semiconductor” model of the composite structuring. For our case of the long-acting hundreds nanometer interactions, the polymer crystallization depends on sp3 C-C bonds organization in the intrinsic electric field according to the semiconductor n-p model. Tensile strength for polyamide-6 composites at 0.25% CNTs increases 1.7 times and tensile deformation – 2.3 times.
Abstract: We analyzed “semiconductor” model of the “polymer-CNTs” composite strengthening at 300 K and low (0.1-0.5) wt% CNTs concentration. Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. We investigated influence of vibration bonds on polymer crystallization and strengthening in composite f...
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Carbon-Carbon Composition “Expanded Graphite – Multiwalled Carbon Nanotubes”
Sementsov Yurii,
Grebel’na Yulia,
Strelchuk Victor,
Dovbeshko Galyna,
Zhuravskyi Serhii,
Makhno Stanislav,
Wang Bo,
Kartel Mykola
Issue:
Volume 8, Issue 6, November 2019
Pages:
127-134
Received:
20 August 2019
Published:
9 December 2019
Abstract: It is given the description of expanded graphite (EG) as a cluster-assembled nanoscale system. It is shown that in the structure of EG there are both extended defects formed by the convolution of one or more graphene layers and orientation defects - disclination. The strength characteristics of EG compacted materials can be controlled by changing the parameters of the production process in a limited interval (the ratio of the amount of oxidizing agent, intercalant, with natural dispersed graphite, its particle size). The procedure for treating multiwalled carbon nanotubes (MW CNTs) with a solution of potassium dichromate in sulfuric acid was carried out according to the known technology of oxidation of natural graphite in order to obtain expandable graphite. It provides for the use of sulfuric acid as an intercalating agent and potassium dichromate (K2Cr2O7) as an oxidizing agent. The aqueous dispersion of oxidized MW CNTs is stable over time: the average particle size is 50 nm; two fractions - from 20 to 100 nm, amount - 99.9%, mass - 10%; from 250 to 500 nm and amount of 0.1%, mass - 90%; high polydispersity ranges from 0.35-0.4, that is, the particles are quite close to the spherical shape. Modification of CNTs by oxygen simultaneously with anodic oxidation of natural dispersed graphite allowed for the first time to create a carbon-carbon composite "EG – MW CNTs" with enhanced physical and mechanical characteristics without additional use of binders.
Abstract: It is given the description of expanded graphite (EG) as a cluster-assembled nanoscale system. It is shown that in the structure of EG there are both extended defects formed by the convolution of one or more graphene layers and orientation defects - disclination. The strength characteristics of EG compacted materials can be controlled by changing t...
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Modification of Specialty Rubbers by Carbon Nanomaterials
Trachevskyi Viacheslav,
Kartel Mykola,
Sementsov Yurii,
Zhuravskyi Serhii,
Wang Bo
Issue:
Volume 8, Issue 6, November 2019
Pages:
135-138
Received:
20 August 2019
Published:
9 December 2019
Abstract: In the elements of aviation structures of large size and low rigidity rubber thermal protective coatings are used, which do not collapse when the structure is deformed. The use of rubber for supersonic aircraft and spacecraft is limited due to high requirements for heat and frost resistance of materials, as well as to their stability under the conditions of radiation and in a vacuum. Therefore, the development of new rubber with improved characteristics is an urgent problem. Multiwall carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. Carbon nanotube aspect ratio of length to diameter is more than 103; this distinguishes it from other nanoparticles. New composites with carbon nanotubes (CNTs) as additives were studied intensively during the last decade. Composites are characterized by extremely high specific strength properties, electrical and thermal conductivity. The effect of multiwalled carbon nanotubes on the performance characteristics of rubbers based on nitrile-butadiene was studied with various methods of their preliminary treatment and introduction into the composition of rubbers. It was shown that the introduction of 0.5-1.0 wt. % сarbon nanotubes into elastomers of different chemical structures leads to an increase in their physic mechanical characteristics, wear resistance and aging resistance, which significantly increases the service life of such products.
Abstract: In the elements of aviation structures of large size and low rigidity rubber thermal protective coatings are used, which do not collapse when the structure is deformed. The use of rubber for supersonic aircraft and spacecraft is limited due to high requirements for heat and frost resistance of materials, as well as to their stability under the cond...
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