Composite Materials
Klaudia Hurtukova; Nikola Slepičková Kasálková; Dominik Fajstavr; Anna Kutová; Petr Slepička
Abstract
In this study, we prepared hybrid materials with C and Ag layers on the surface of polydimethylsiloxane polymer (PDMS). The prepared samples were subjected to thermal treatment and modification with high energy KrF excimer laser in single shot mode. The change in the surface morphology of the samples ...
Read More
In this study, we prepared hybrid materials with C and Ag layers on the surface of polydimethylsiloxane polymer (PDMS). The prepared samples were subjected to thermal treatment and modification with high energy KrF excimer laser in single shot mode. The change in the surface morphology of the samples was investigated by Scanning Electron Microscopy (SEM), and the chemical composition of the prepared nanocomposites was studied by Energy Dispersive Spectroscopy (EDS). Finally, the samples were tested for antibacterial activity using two bacterial strains of Gram-positive S. epidermidis and Gram-negative E.coli. Antibacterial properties were observed on the prepared samples in both bacteria colonies.
Composite Materials
Anna Kutová; Ondřej Kvítek; Klaudia Hurtuková; Václav Švorčík
Abstract
Nowadays, new materials for the preparation of synthetic bone grafts are being sought after. Bones consist mainly of collagen fibres and hydroxyapatite crystals, so using synthetic grafts with a similar structure is logical. Therefore, a composite material was prepared by adding hydroxyapatite particles ...
Read More
Nowadays, new materials for the preparation of synthetic bone grafts are being sought after. Bones consist mainly of collagen fibres and hydroxyapatite crystals, so using synthetic grafts with a similar structure is logical. Therefore, a composite material was prepared by adding hydroxyapatite particles in the cultivation medium of bacterial nanocellulose (in-situ method). The composites were dried via air-drying and lyophilization to obtain solid materials. The formation of the composite was confirmed by infrared spectroscopy, which showed cellulose (OH vibrations) as well as hydroxyapatite (PO43- vibrations) absorption bands. Energy dispersive X-ray spectroscopy showed presence of 14 wt% of calcium and 48 wt% of phosphorus in the composites. The structure of the hydroxyapatite crystals embedded in fibrous cellulose was observed by scanning electron microscopy. The higher porosity of the lyophilized samples was confirmed as well. Water contact angle of the air-dried composites was lower (25 ± 3.6)° compared to pure bacterial nanocellulose (30 ± 2.7)°. The mechanical strength of the air-dried composites was (20.3 ± 7.9) MPa. These results suggest the prepared material is promising for construction of synthetic bone grafts.
Composite Materials
Elguja Kutelia; Kusman Dossumov; Gaukhar Yergasiyeva; David Gventsadze; Nikoloz Jalabadze; Teimuraz Dzigrashvili; Lili Nadaraia; Olga Tsurtsumia; Manshuk Mambetova
Abstract
This study first demonstrated the possibility of the production of catalyst supports in the form of granules and tablets composed of nanoparticles of Fe atom cluster-doped CNTs using mini-mold forming and spark plasma sintering (SPS) techniques respectively. The pilot samples of the novel catalyst system ...
Read More
This study first demonstrated the possibility of the production of catalyst supports in the form of granules and tablets composed of nanoparticles of Fe atom cluster-doped CNTs using mini-mold forming and spark plasma sintering (SPS) techniques respectively. The pilot samples of the novel catalyst system containing 3% NiO active phase, synthesized on the granulated Fe cluster-doped CNTs carrier, were tested to determine their catalytic activity and coking resistance in the DRM reaction, in a wide range of temperatures up to 900oC. The developed novel catalyst systems’ samples were characterized before and after the catalyst reaction using SEM, EDX, XRD, and AES methods. It is shown that the temperature dependence of the catalytic activity of the 3% NiO catalyst, supported on the granulated Fe cluster-doped CNTs carrier, revealed two characteristic temperature ranges with different rates of efficiency. Particularly, at high reaction temperatures, starting from 700oC, the conversion rates of methane and carbon dioxide (42.4% and 45.6% respectively) have more than doubled at 850oC. Starting from 850oC to 900oC the latter tends to exceed the carbon dioxide conversion rate, and at 900oC it amounts to 95%.
Composite Materials
Daniel Dubecky; Vincent Kvocak; Michala Weissova
Abstract
Composite polymer-concrete beams represent new modern structures that can take an advantage of the polymer's practical tensile properties and combine them with the concrete's favourable compressive properties. Drawing on this knowledge, a set of polymer beams acting compositely with a concrete slab was ...
Read More
Composite polymer-concrete beams represent new modern structures that can take an advantage of the polymer's practical tensile properties and combine them with the concrete's favourable compressive properties. Drawing on this knowledge, a set of polymer beams acting compositely with a concrete slab was designed and manufactured. The aim of the research was to utilise the low weight and high strength of the polymer I-sections and combine them with the high stiffness of the concrete slab, which forms the upper part of the cross-section. The advantage of fibre-reinforced polymer (FRP) beams is their anisotropy, where the strength of the material is increased by placing the fibres uniformly in one direction, and the composite elements are then stressed in the most reinforced direction. To ensure the interaction between the polymer element and the concrete slab, strip shear connectors of a precisely defined shape were developed and utilised. The designed composite beam simulates a pre-cast component that can be applied in bridge structures for short and medium spans. The pre-cast beams were subjected to four-point bending. Apart from the overall deflections of the structure, the stresses in the cross-section of the composite material and the relative deformations/strains on the surface of the concrete part of the cross-section were monitored during the test. The whole experiment yielded new results in both laboratory and theoretical respects, not only regarding the interaction of materials with distinct characteristics but also the properties of composites per se.
Nanomaterials & Nanotechnology
Miranda Benavides; Denis Leonardo Mayta; Fernando Alonso Cuzziramos; Gerhard Paul Rodriguez; Fredy Alberto Huaman-Mamani
Abstract
The traditional method of manufacturing SiC compounds is associated with a serious environmental problem, mainly due to the need for large amounts of energy (generally derived from oil) to reach processing temperatures (typically above 2500 ºC). In addition, the chemical reaction that gives rise ...
Read More
The traditional method of manufacturing SiC compounds is associated with a serious environmental problem, mainly due to the need for large amounts of energy (generally derived from oil) to reach processing temperatures (typically above 2500 ºC). In addition, the chemical reaction that gives rise to the formation of SiC has CO and CO2 as by-products. Therefore, in this work an alternative method to manufacture SiC/Si composites using waste from the wood industry as the main raw material was developed. SiC/Si composites were fabricated by infiltration of molten silicon into carbon preforms at 1500 °C. The carbon preforms were obtained by pyrolysis (in an inert Ar atmosphere) of four types of resin-carbon mixtures. The carbon used in the mixtures was obtained by pyrolysis of sawdust powder.The mechanical and thermomechanical behavior in uniaxial compression was studied at a constant compression rate of 0.05 mm/min at different temperatures (ambient, 1100 °C and 1400 °C). The maximum resistance values found were in the range of 58 and 384 MPa, while the Young's modulus values were between 40 and 120 GPa. The porosity found in the materials was between 1 and 4%. Finally, the fabricated compounds presented a homogeneous microstructure of interconnected silicon carbide in gray contrast and dispersed and unconnected whitish phases of uniformly distributed silicon.
Composite Materials
Kamil Janeczek; Mateusz Kosyl; Aneta Araźna; Michał Czaiński; Krzysztof Lipiec; Wojciech Stęplewski; Marek Kościelski
Abstract
Passive fire protections are one of the safety systems which are installed commonly in buildings. As every kind of such systems these protections have to controlled according to legal regulations. To facilitate periodic checks RFID technology can be successfully used. In this paper, thermal behaviour ...
Read More
Passive fire protections are one of the safety systems which are installed commonly in buildings. As every kind of such systems these protections have to controlled according to legal regulations. To facilitate periodic checks RFID technology can be successfully used. In this paper, thermal behaviour of produced swelling materials suitable for passive fire protection was examined and thermal endurance of RFID tags used to identify these protections was analysed as well. The results achieved in this study showed expected thermal behaviour of the swelling materials which fulfilled the whole space of the protections blocking spreading fire and smoke. Further, it was noticed that a gasket sealant and a high-temperature silicone allowed to decrease temperature affecting RFID tags. Paper-face and hard RFID tags withstood the applied thermal exposure and their readability was restored after cooling down the tags to about 120°C. This means that it is likely that these tags can resist small fire incidents on condition that temperature affecting the tags does not exceed a decomposition temperature of materials used for their production.
Composite Materials
Chang Che; Shaohai Ma; Qingchuan Pan; Kai Yan; Gong Qian
Abstract
Super304H (18Cr-9Ni-3Cu-Nb-N) austenite steel has high creep strength and has been used as the material of tubes in 600℃ class supercritical power plants in China. Many Super304H materials have run for more than 100,000 hours. Long-time service feature of these austenitic stainless steels has not been ...
Read More
Super304H (18Cr-9Ni-3Cu-Nb-N) austenite steel has high creep strength and has been used as the material of tubes in 600℃ class supercritical power plants in China. Many Super304H materials have run for more than 100,000 hours. Long-time service feature of these austenitic stainless steels has not been understood. An understanding of the long-term microstructural evolution under actually used conditions is a key for the improvement of these heat resistant steels. In this article, creep behavior of Super304H used in China plants was analyzed, microstructural evolution of Super304H materials after different service conditions were studied involving in optical microscope, TEM and SAXS. The results show, M23C6, Cu-rich particles, and σ phase were found to precipitate. A quantitative assessment of microstructure evolution was given during long-term creep.
Composite Materials
Fiza Simran; Prathiksha Karumbaiah; Pratik Roy; R.R.N. Sailaja
Abstract
The present study is aimed to remove toxic crystal violet dye from aqueous solutions. In this study guar gum (GG) has been grafted with acrylic acid (AA) by following microwave assisted grafting method. Two different nanomaterials i.e., nanoclay (NC) and multiwalled carbon nanotubes (MWCNT) has been ...
Read More
The present study is aimed to remove toxic crystal violet dye from aqueous solutions. In this study guar gum (GG) has been grafted with acrylic acid (AA) by following microwave assisted grafting method. Two different nanomaterials i.e., nanoclay (NC) and multiwalled carbon nanotubes (MWCNT) has been incorporated either alone or in combination during the grafting reaction. The synthesized nanocomposites have been used for removal of crystal violet dye from aqueous solutions. Study showed higher dye adsorption capacity of the synthesized composites after addition of nanomaterials. The adsorption isotherm followed both Langmuir and Freundlich model. It was found that GG grafted AA composite with MWCNT showed highest crystal violet dye adsorption compared to others. Swelling behaviour of the synthesized composites in acidic, neutral and alkaline medium has been studied. The swelling kinetics in acidic, neutral and alkaline medium was found to follow pseudo second order kinetic model with <R2> value more than 0.98. Fourier transform infrared spectroscopy (FTIR) showed efficient grafting of AA on GG. X-ray diffraction (XRD) and morphological characteristics depicted enhanced dispersion of nanomaterials in GG matrix.
Composite Materials
Rajani Malathi Alupatla; G. S. Kumar; G. Prasad
Abstract
Mixed system of (1-x)Na0.5Bi0.5TiO3+(x)SrTiO3 (NBT-ST) where x=0.075, 0.125, 0.150, 0.200 ferroelectric ceramic materials are synthesized using modified pechini method. These optimized compositions are used for study of polarization versus electric field (P-E) loops. The ferroelectric response of the ...
Read More
Mixed system of (1-x)Na0.5Bi0.5TiO3+(x)SrTiO3 (NBT-ST) where x=0.075, 0.125, 0.150, 0.200 ferroelectric ceramic materials are synthesized using modified pechini method. These optimized compositions are used for study of polarization versus electric field (P-E) loops. The ferroelectric response of the samples is investigated as a function of temperature. Remnant polarization of exhibited loops observed to decrease with increasing temperature. PE data is used to estimate the electrocaloric properties. Maximum entropy change, full width at half maximum, relative cooling power is obtained from theoretical calculations.
Composite Materials
A.I. Alateyah
Abstract
In this study, the severe plastic deformation (SPD) behavior of commercial-grade pure copper processed using equal channel angular pressing (ECAP) was investigated. The copper rods were processed for up to 4 passes, both at room temperature and 200 oC. The microstructure and texture evolution were studied ...
Read More
In this study, the severe plastic deformation (SPD) behavior of commercial-grade pure copper processed using equal channel angular pressing (ECAP) was investigated. The copper rods were processed for up to 4 passes, both at room temperature and 200 oC. The microstructure and texture evolution were studied using a field emission scanning electron microscope (FESEM) equipped with an electron back scattered (EBSD) detector. The effect of ECAP processing on the tensile properties, micro-hardness, and impact toughness was studied. After 1 pass, the average grain size of the rods was determined to be 2.694 and 3.9066 μm at room temperature and 200 oC, respectively. In addition, after 4 passes through ECAP, the strength of the ECAPed samples increased to 381 MPa, and 330 MPa at room temperature and 200 oC, respectively; and the Vickers’ micro-hardness at the peripheral areas increased to 158, and 126, respectively. In the other hand, the experimental findings revealed that the number of ECAP passes has insignificant effect on the impact energy.
Composite Materials
Rajnish Raj; Pooja Lohia; D. K. Dwivedi
Abstract
The traditional melt-quench technique was used to synthesize non-oxide (Ga2Ge)100-x(Ga3Sb2)x (x = 15, 30, 45, 60) glass alloys. The vacuum thermal evaporation unit was used to obtain thin films of prepared sample for investigation of optical properties. SEM, XRD and DSC technique were used to find the ...
Read More
The traditional melt-quench technique was used to synthesize non-oxide (Ga2Ge)100-x(Ga3Sb2)x (x = 15, 30, 45, 60) glass alloys. The vacuum thermal evaporation unit was used to obtain thin films of prepared sample for investigation of optical properties. SEM, XRD and DSC technique were used to find the thermal and structural properties of the materials. The linear properties like optical bandgap, extinction coefficient for prepared samples have been studied in present paper of Ge-Ga-Sb for application of optoelectronics. The impurities present in the prepared thin films were defined by FTIR transmittance spectra. The extinction coefficient (k) value decreases with increase in Sb concentration while absorption coefficient (α). It was noticed that value of energy bandgap (Eg) derived from Tauc’s plot varies from 2.9 eV to 1.25 eV. Urbach energy is inversely proportional to the bandgap of the materials. As the Sb concentration increases the band gap goes on decreases which result the increase in Urbach energy. Mott and Davis model has been used for explaining decrease in energy gap of prepared glassy alloys.
 Nanocomposites Induced by Hi ... ', 'data/aml/coversheet/801668438703.jpg'))
)
)
)
)