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Results in Journal Solid State Phenomena: 13,935

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, , Antje Täger, Hagen Marks
Solid State Phenomena, Volume 267, pp 114-118;

For electrostatic coating application Sheet Molding Composites (SMC) have to be modified antistatically. By a novel approach several monomeric and polymeric ionic substances were incorporated into the duromeric bulk phase and tested in terms of its antistatic effectiveness. Furthermore the influence of selected additives on the SMC thickening and molding procedure as well as resulting mechanical properties of modified SMC-panels and the powder coating application were studied.
, , Mart Viljus, , Priit Kulu
Solid State Phenomena, Volume 267, pp 195-200;

The present research focuses onto sliding wear of novel plasma transferred arc welded (PTAW) hardfacing with the stainless steel (DIN X3CrNiMo18-13-3) matrix, reinforced with WC/W2C, under the room and elevated temperature. The hardfacing was produced, applying the optimized set of parameters (current – 55 A, reciprocating speed – 1.0 mm/s, oscillation frequency – 0.6 Hz). The average reinforcement content was 29.3 ± 4.0 vol %. The reinforcement consisted of W2C and WC, while M7C3- and M23C6-type (M = Fe, Cr, Mo, W) carbides were the main phases in the matrix. Universal hardness and Young’s modulus were approximately 5.3 and 1.9 times higher, than those of the reference steel (DIN X2CrNiMo18-14-3). The sliding wear of the hardfacing was 4.9 times lower under 20 °C and 3.1 times lower under 300 °C, but 1.8 times higher under 500 °C than the wear of the reference steel. Galling was the wear mechanism of the hardfacing under 20 °C, scoring – under 300 °C and combination of scoring and binder extrusion – under 500 °C
, Armands Buss, , Lasma Malniece
Solid State Phenomena, Volume 267, pp 119-123;

α-Tricalcium phosphate (α-TCP) is an important reactive component in calcium phosphate bone cements which are used for the bone tissue regeneration and augmentation. By thermally treating amorphous calcium phosphate (ACP) at relatively low temperatures (650–900 °C), it is possible to obtain sub-micrometre or nanosized α-TCP particles. In the current research, it is shown that the aqueous synthesis environment where ACP is precipitated has significant influence on the stability of ACP and the α-TCP content in the thermally treated products. During ACP synthesis pH must be kept basic. While it is possible to synthesize ACP if potassium hydroxide or sodium hydroxide is used to raise the pH of synthesis, ammonium ions also must be present in the solution to obtain α-TCP after thermal treatment of ACP. If sodium hydroxide is used, higher α-TCP content is obtained (compare 89 % and 66 %). Increase of Ca/P ratio stabilizes ACP and allows to obtain products with high α-TCP content. Increase of both calcium and phosphate ion concentration in the synthesis destabilizes ACP and reduces the amount of α-TCP in the product (twofold increase reduced α-TCP content from 89% to 2%).
, , Karl Adam, Andreas Kuttner
Solid State Phenomena, Volume 267, pp 234-242;

In heavy industries like mining or steel production vast amounts of loose materials need to be transported, relocated or otherwise processed. During these routines severe stresses are applied on heavy machinery components such as excavator grabs and clamshells, which ultimately lead to excessive wear. The dominant wear mechanisms under such conditions are impact and abrasion. The focus of this paper is to investigate the fracture behaviour of various abrasives as experienced under real application in the steel industry. Breaking events of abrasive particles affect the impact energies on tool equipment. The Cyclic Impact/Abrasion Test rig (CIAT) was applied to investigate the stability and fracture behaviour of the abrasives. Rotating counter bodies made of martensitic quenched and tempered steel were used to generate impact events on loose abrasive particles. After certain time intervals the abrasives were screened and particle size fractions documented. Impact energy is strongly dependent on size and density, as well as fragility and cracking of particles. As fracturing events diminish particle dimensions and shift size distributions to lower size fractions, each abrasive showed a distinctive impact energy distribution over the course of the test duration. Impact energy distributions of abrasives were correlated to wear rates of the steel samples for each abrasive used. The results indicate a distinct behaviour of each abrasive, yielding certain impact energy distributions. Depending on processing specific abrasive goods in actual applications, impact energies and associated wear loss can differ significantly.
Belkacem Bouacherine, Abdelkader Iddou, Hafida Hentit, Jean Claude Jumas, ,
Solid State Phenomena, Volume 267, pp 139-144;

This work is in addition to the various works undertaken by the researchers, using biomass as adsorbent. However, the aim of this study is the recovery of a marine material alga: Ulva lactuca) that we were able to transform into adsorbent with treatment under physical carbonization and chemical activation. The ability of treated and untreated Ulvala ctuca, to remove hexavalent chromium Cr (VI) ions in aqueous solutions was investigated. The influence of pH, sorbent dose, initial concentration, temperature, and contact time has been studied in batch process. The materials are characterized by FTIR and SEM analysis. The highest Cr (VI) removals (100%) were achieved at pH of 3, particle size of less than 250μm, dose of 1 g/L, and equilibrium time of 180 minutes. Thermodynamic results indicated that the Cr (VI) adsorption process was spontaneous and exothermic. The adsorption data fit well with Langmuir isotherm model with a maximum adsorption capacities (qmax) of untreated and treated Ulva lactuca were between 0.6 and 2 mg/g. Higher Cr (VI) removal revealed the practical applicability of Ulva lactuca in water and wastewater treatment systems.
Solid State Phenomena, Volume 267, pp 40-44;

Pneumatic vibroexciters which consist of smart materials’ structural elements and are operating under autovibration regime were designed. The chamber of vibroexciter actuator with changeable capacity for flowing pressured air made of shape memory alloy (SMA) were presented. Mechanical characteristics of such type vibroactuator were estimated: maximum deformation of structural element with SMA, possible force of martensitic transformation. The result of the research allows to design functional adaptive pneumatic vibroexciters with are suitable for the different purposes of technological processes.
Solid State Phenomena, Volume 267, pp 124-131;

Variety of different bone substitutive materials are synthetized to improve bone healing potentials in pathological bone conditions. Physiologically active molecules within biomaterials, can initiate expression level of biomarkers, regulating bone remodeling. Aim of our study was to analyze bone healing process in bone defects followed by implantation with 5% strontium substituted hydroxyapatite (HAP) /tricalcium phosphate (TCP) 70/30 granules (group A) or HAP/TCP biphasic ceramic granules without strontium substitution (group B), or sham surgery affected bone (group C) in osteoporotic rabbits’ femur. Tissue samples from contralateral intact left leg were used for evaluation of systemic effects after surgery. Changes of bone volume were measured and appearance of OPG, NFkB-105, OC, COL-1, BMP-2/4, MMP-2, TIMP-2, IL-1 and IL-10-positive osteocytes in osteoporotic rabbits’ bone defect were evaluated. No statistical difference between groups of trabecular bone volume was detected. All analyzed markers showed higher appearance of positive osteocytes in groups A and B with comparison to control left leg (p<0.05). Only NFkB105-positive cells showed important difference between sham surgery affected leg and control one (p=0.034). Numerous OPG-positive cells appeared in group A, while moderate number of them was found in groups B and C (p=0.025; p=0.027). Numerous to abundant OC-positive osteocytes were detected in group A, while moderate in group C (p=0.034). Statistical difference of rest biomarkers between groups was not detected. We concluded that implantation of biomaterials in osteoporotic bone improves local bone regenerative properties. However, the notable increase of OPG-containing cells proves the increase of osteoclastogenesis suppression and gives the evidence for renew of bone functionality.
Marek Góral, Tadeusz Kubaszek
Solid State Phenomena, Volume 267, pp 243-247;

Thermal Barrier Coatings (TBC) is the most advanced system for protection of turbine blades and vanes against high temperature, and oxidation. They are used in most advanced jet engines. In present article the new Plasma Spray Physical Vapour Deposition Technology was used to obtain yttria stabilized zirconia oxide coating with columnar structure. In research the different process parameters were changed. It was observed that powder feed rate had big influence on coating thickness. The large amount of Ar in plasma gasses combined with high powder feed rate resulted in partial evaporation of ceramic powder and splat-type structure. The same effect was observed when the power current was decreased form 2400 to 1600 A as well as pressure was increased to 200 Pa when the powder feed rate was 30 g/min. The obtained results showed that full evaporation of ceramic powder requires very low feed rate of ceramic material (2 g/min), high power current and high He content into plasma.
Ali Ozturk
Solid State Phenomena, Volume 267, pp 177-181;

This paper presents how to calculate the overall heat transfer coefficient of a very long functionally graded hollow circular cylinder subjected to steady state heat transfer. Thermal conductivity coefficient of the functionally graded cylinder (FGC) vary radially and continuously according to an exponential form, which is supposed to be independent of the temperature. Overall heat transfer coefficient is found analytically in terms of the radial coordinate, thermal conductivity, material parameter, inner surface and outer surface temperatures of the cylinder. Once the overall heat transfer coefficient is found, calculation of the heat transfer rate across the cylinder wall is quite straightforward. The equation derived for the overall heat transfer coefficient can be applied to any type of functionally graded hollow circular cylinder playing with the material parameter term.
Jevgenijs Jaunslavietis, , Jurijs Ozolins, Brigita Neiberte, Anrijs Verovkins, , Vadims Shakels
Solid State Phenomena, Volume 267, pp 68-75;

The aim of the study was to evaluate the surface energetic characteristics of wood-polymer composites (WPCs) based on recycled polypropylene (rPP) filled with ammoxidised lignocellulosic microparticles, obtained from aspen sawdust, a by-product of a Latvian company. The aspen sawdust, pre-hydrolysed in acidic medium, was treated with a reaction mixture of ammonium persulphate and NH4OH solution at their defined mass ratio during 120 h. The content of the introduced nitrogen was varied from 1,05 to 2,10%. It was found that the ammoxidation that was accompanied with the formation of amide linkages and the decrease of the hemicelluloses content enhanced the contact angles, decreased the work of adhesion and reduced the surface free energy of the WPC samples in comparison with the case of the composite filled with the initial sawdust. The valorisation of the wood particles increased their wettability towards the recycled polypropylene that had a positive effect on the WPC samples’ mechanical properties.
Solid State Phenomena, Volume 267, pp 82-86;

Cr3C2-Ni cermets exhibit high hardness and excellent corrosion, oxidation, abrasive and erosion resistance. However, nickel is toxic and carcinogen and because of that great efforts were made to displace or replace nickel in the composition of cermets. Therefore, in the present research chromium carbide-based cermets with FeCr-type ferritic binder was fabricated and investigated. Composites were sintered at different conditions: vacuum and spark plasma sintering. Spark plasma sintered cermets demonstrated acceptable structure and mechanical characteristics. Chemical composition of chromium carbide-based iron alloy bonded cermets was analyzed by energy-dispersive X-ray spectroscopy and structural analysis was carried out using X-ray diffraction. Sintered cermet consists of two main phases: α-Fe and (Cr,Fe)7C3 complex dicarbide. Mechanical characterizations – hardness and fracture toughness – was performed. Also oxidation rates were determined.
, , Mārtiņš Kalniņš
Solid State Phenomena, Volume 267, pp 7-11;

This report explores two key manufacturing processes, and assesses multiple parameters for optimization of these processes. High shear dispersion using a rotor-stator style homogenizer and high-energy grinding using a basket type mill with zirconium balls as the grinding media were studied. The variation between grinding organic and inorganic pigments was assessed as they give different challenges and require different operations to produce successful results. Obtaining the correct particle size distribution of pigments for decorative coatings is of paramount importance for achieving a high quality, functioning, aesthetically pleasing finished product. This analysis will explore the de-agglomeration and dispersion of inorganic TiO2 and organic Red 6 pigments using basket milling technology. High energy basket mill grinding produced the smallest particle size and smallest particle size distribution comparing with high shear dispersion. Used technology allowed to achieve inorganic pigment TiO2 particle size and particle size distribution suitable for use in coatings on natural nails. For organic pigment Red 6 used technology should be customized.
Alexey Tatarinov, Viktor Mironov, Dmitry Rybak, Pavels Stankevich
Solid State Phenomena, Volume 267, pp 248-252;

Possibilities of non-destructive testing (NDT) methods to assess the quality of permanent joints of powder metal parts were evaluated. Antifriction bushing-bushing couples used in transport braking systems were investigated. The parts made of bronze graphite were crimped by pulsed magnetic deformation by means of electromagnetic equipment with a maximum discharge energy of 30 kJ. The gap between joint parts in the couples was assessed by ultrasonic and radiographic methods. A standard ultrasonic flaw detector Krautkramer USM-25 with an Olympus 4MHz dual-element echo transducer and an industrial x-ray apparatus YXLON EVO 200D were used, correspondingly. In first trial, both methods were equally sensitive to tight and weak connection of joints.
Maxim Yashin, , Pradeep L. Menezes, Mart Viljus, Taavi Raadik, Andrei Bogatov, ,
Solid State Phenomena, Volume 267, pp 219-223;

The present study deals with the tribological behavior of nanocrystalline diamond (NCD) coatings at high temperature sliding conditions. The NCD coatings were grown by plasma enhanced chemical vapor deposition (PECVD) method on the hard metal (WC-Co) substrates. The friction and wear tests were performed on ball-on-disc tribometer using a high-temperature chamber with rotary drive. The tests were carried out at room temperature, 300, 450 and 600 °C. The scanning electron microscopy (SEM), optical microscopy, mechanical profilometry and Raman spectrometry were used for investigation of the morphology and chemical composition of the wear scars and pristine surface. The depth and width of the wear scars measured after the high temperature sliding tests are larger in comparison with room temperature tests. It was observed that the coefficient of friction (COF) increased with increasing temperature. The wear rate of NCD coatings tested at 300-450° C was about 10 times higher than that at room temperature. The mechanisms involved for these variations are discussed.
Radomila Konečná, , Pavel Pokorný,
Solid State Phenomena, Volume 267, pp 157-161;

Growth of long fatigue cracks in Ti6Al4V alloy manufactured by direct metal laser sintering (DMLS) was investigated. Two DMLS systems, EOSINT M270 and EOSINT M290, with different process parameters were used for production of CT specimens having three different orientations of crack propagation with respect to the DMLS build direction. The as-built specimens were stress relieved at 740 °C. The fatigue crack growth curve and the threshold values of the stress intensity factor for crack propagation were experimentally determined. It has been found that the chosen DMLS processing parameters and the used stress relieving procedure results in material exhibiting isotropic crack growth behavior, i.e. the crack growth was found to be independent of the DMLS build direction. The fatigue crack growth rates and the threshold values for the crack growth were compared with published results characterizing the as-built material and material after different post processing heat treatments.
Solid State Phenomena, Volume 267, pp 151-156;

In the present study, buckling of eccentrically loaded nanobeams in which the load is not applied at the centroid of cross section, has been studied. Eringen’s Nonlocal Elasticity Theory has been used in the formulation of governing equation of motion of the nanobeam. Simply supported and free boundary conditions for nanobeam have been taken consideration. The effect of nonlocal parameter, eccentricity of the load, nanobeam length on the buckling deflection and critical buckling load on nanobeam have been investigated. Present results can be useful in the design of nano-structures.
, Andrejs Skagers
Solid State Phenomena, Volume 267, pp 145-148;

Sinus floor augmentation operations with calcium phosphate materials are performed when natural maxillary bone quality and quantity fail to be able to support titanium dental implants. Sinus floor augmentation can be done in one step operation when titanium implant is inserted at the same time when calcium phosphate materials. This type surgery can be done if there is enough maxillary alveolar bone height to stabilize the implant. If there is not enough bone then two step maxillary floor augmentation is performed when dental implant is placed after few months. Calcium phosphate materials are often used for maxillary sinus augmentation. These materials cause remineralization of residual maxillary alveolar bone [1]. That can be observed histologically [2,3]. However histological evaluation often means interference. Radiological investigation can be used to examine postoperatively augmented area. Nowadays cone beam computed tomography (CBCT) is the radiological method of choice for maxillofacial region due to low radiation and high quality images. There was no date found in literature on maxillary bone remineralization measured in voxel grey value density (VV) on CBCT. Rotation movement of CBCT cause beam hardening artifacts [4,5] that can alter correct measurements of bone and augmentation zone radiodensity. The aim of this study was to calculate remineralization of maxillary alveolar bone after augmentation with calcium phosphate materials radiologically and degree of artifacts created by titanium dental implant in CBCT images.
Ritvars Berzins, ,
Solid State Phenomena, Volume 267, pp 28-34;

Two component model systems from Silyl-terminated polyether (SAX 520) and epoxy resin (D.E.R. 331) can produce higher mechanical properties than each system individually. This work is dedicated to explore two components (SAX 520/D.E.R. 331) systems and represent their benefits comparing to neat SAX 520 based system. Work shows that compositions with epoxy resin not only improves material mechanical properties, but also its stability after aging, workability time and adhesion on various substrates.
Sinan Sezek,
Solid State Phenomena, Volume 267, pp 45-51;

In this study, temperature distribution that occurred during cold and hot rolling of AA5454-O alloy has been investigated. Temperature variation taking place in the aluminium alloy that has undergone plastic deformation between the rollers during hot and cold rolling process is of major importance in terms of determining the positive and negative characteristics or features which such temperature variation adds to the formation of the internal structure of the material concerned. Temperature distribution has been measured by use of the installed laboratory equipment and respective data recorded has been presented in the form of graphic charts. Temperature distribution has varied depending on the application of hot or cold rolling process and it has been noted that variations in terms of temperature reduction took place depending on the number of roll passes. While average temperature variation has occurred as a 16°C increase in the case of cold rolling, it has been observed that such variation appeared as a 100°C decrease on the average in the case of hot rolling.
Tadeusz Kubaszek, Marek Góral
Solid State Phenomena, Volume 267, pp 207-211;

The aim of this study was to examine the possibility of application in APS process Yttria Stabilized Zirconia (YSZ) – Metco 6700 ceramic powder normally used in Low Pressure Plasma Spraying (LPPS) method. Powder grain size is around 10 µm. Parameters such as chemical composition of plasma gases and current were changed to obtain the best result. The experiment was divided into two stages. Firstly, temperature, velocity and size of a molten particle of ceramic powder inside plasma plume were measured via DPV eVolution equipment (TECNAR company) during a different set of process parameters. Plasma plume was also scanned to obtain cross-section contour plots of mentioned properties of the molten particle. Secondly, the same processes were repeated to deposit TBC coatings onto sheet metal to examine the structure.The obtained results showed that it is possible to use fine-grain YSZ powder Metco 6700 for APS process. Obtained ceramic coatings had a thickness from 100 to 240 µm. The plasma sprayed coating was characterised by a smooth surface. The measurement of spraying parameters showed the uniform temperature, velocity and particle size of the powder inside plasma plume.
Marianna Laka, Marite Skute, Sarmite Janceva, Velta Fridrihsone, , Linda Vecbiskena, Uldis Grinfelds, Laura Andze, Juris Zoldners
Solid State Phenomena, Volume 267, pp 12-16;

For reinforcing of paper, nanoparticle gels from black alder, birch and pine bark were obtained. Non-extracted bark and that extracted in biorefinery were used. For producing nanoparticles, the materials were destructed using the thermocatalytic destruction method and then dispersed in water medium in a ball mill. At a sufficient concentration, gel-like dispersions were obtained, which contained nanoparticles with the size ~300 nm. The effect of nanoparticle gels on the properties of paper sheets was investigated by introducing the dissolved gels in paper furnish and by covering both sides of paper sheets with nanoparticle gel coatings. It has been established that the nanoparticle fillers increase the tensile and burst strength. The nanoparticle fillers from extracted bark increase the mechanical indices to a higher extent. The coatings from nanoparticle gels considerably improve the Gurley air resistance of paper and increase the mechanical indices of paper sheets, especially burst strength. The effect of nanoparticle gel coatings is dependent on the coating thickness and gel concentration. The coatings decrease the tensile strength in a wet state.
Jing Fu Song, , Qing Jun Ding, Jin Hao Qiu
Solid State Phenomena, Volume 267, pp 253-257;

Space exploitation and development need high-performance polymer based tribo-materials in order to reduce the weight and improve the reliability of mechanical moving components. However, the wear resistance of polymer composites will decrease after space irradiation. In order to improve the anti-irradiation and wear resistance, the high performance polyimide (PI) composites reinforced with aramid fibers (AF), filled with polytetrafluoroethylene (PTFE) and Al2O3were designed and prepared using hot press sintering. The effect of the individual atomic oxygen or proton irradiation as well as both on the tribological properties of the PI composites were systematically investigated against Si3N4 ball on a ball-on-disk test rig under simulating space environment system, and coefficient of friction and wear rate were considered as responses. The worn surfaces of the composites were observed by scanning electrical microscopy to reveal wear mechanisms of the materials’ damage. Experimental results indicated that the wear rate of the PTFE/AF/PI greatly increased after atomic oxygen and proton irradiation due to oxidation degradation effect on the polymer matrix. However, filling Al2O3 nano-particles into polyimide matrix can improve the wear resistance because of oxidation layer, gradually formulated during the process of atomic oxygen irradiation, which can protect the polymer composites and avoid further oxidation. This study will expect to provide the helpful guidance for designing high performance polymer based frictional materials in the application of space science.
, , Algirdas Sužiedėlis, Aldis Šilėnas, Edmundas Širmulis, Vitas Švedas, Viktoras Vaičikauskas, Vytautas Vaičiūnas, Darius Valiulis, Ovidijus Žalys, et al.
Solid State Phenomena, Volume 267, pp 167-171;

Photovoltage formation across Si and GaAs p-n junctions exposed to laser radiation is experimentally investigated. When the photon energy is lower than semiconductor forbidden energy gap, the photovoltage is found to consist of two components, U=Uf+ Uph. The first one Uf is fast having polarity of thermoelectromotive force of hot carriers. The second one Uphis slow component of opposite polarity, and it is caused by electron-hole pair generation due to two-photon absorption. Uph was shown to decrease with the rise of radiation wavelength due to diminution of two-photon absorption coefficient with wavelength. Predominance of each separate component in the formation of the net photovoltage depends on both laser wavelength and intensity.
Laura Rozenberga-Voska, Jānis Grabis
Solid State Phenomena, Volume 267, pp 3-6;

TiO2 and silver doped TiO2 thin films were prepared by spray pyrolysis technique and their photocatalytic activity were determined. Titanium(IV) isopropoxide solution or its mixture with silver nitrate were used as precursors. As-prepared at 300 °C films were X-ray amorphous. Calcination of the films at 500 °C for 5 – 6 hours allowed to obtain partially crystalline anatase films with uniform grain size in the range of 80 – 150 nm. Degradation degree of MB water solution by using TiO2 and TiO2/Ag photocatalysts under UV irradiation reached 60 and 70 % respectively.
Kakur Naresh, Shankar Krishnapillai, Ramachandran Velmurugan
Solid State Phenomena, Volume 267, pp 103-108;

In this study, the Interlaminar shear strength (ILSS) and flexural properties for five different laminate orientations [0°, 45°, [45°/-45°/45°]s, [±45°/0°/90°]s and 90°] of unidirectional carbon fiber reinforced plastic (CRP) and glass fiber reinforced plastic (GRP) composites are investigated. The different approach is used by applying the tensile load on notched specimens for measuring the inter-laminar shear strength. The theoretical flexural properties are obtained using the classical laminate theory [CLT]. The good agreement is obtained between the theoretical model and experimental results. The results indicate that the flexural strength and stiffness are higher for 0° laminate whereas flexural strain is higher for [45°/-45°/45°]s laminates as compared to other laminates. The scanning electron microscopy is used to observe the fracture surface of all laminate orientations of CRP and GRP composites.
Emrah Madenci,
Solid State Phenomena, Volume 267, pp 35-39;

The main objective of the present study is to give a systematic way for the derivation of laminated composite plates by using the mixed type finite element formulation with a functional. The first order shear deformation plate theory is used. Differential field equations of composite plates are derived from virtual displacement principle. These equations were written in operator form then by using the Gâteaux differential method, a new functional which including the dynamic and geometric boundary conditions is obtained after provide potential conditions. Applying mixed-type finite element based on this new functional, a plate element namely FOPLT32 is derived which have 8 degrees of freedoms on per node, total 32 freedoms. The reliability of the derived FOPLT32 plate elements for static analysis is verified, since the results obtained have been shown to agree well with the existing ones.
, Mürsel Ekrem
Solid State Phenomena, Volume 267, pp 23-27;

In this study, the production of weight ratios of 1, 3 and 5 % multi-walled carbon nanotubes (MWCNT) reinforced / unreinforced Nylon 6,6 (N-6,6) nanofiber mats was carried out by electro spun method. Tensile strength (sT), modulus of elasticity (E), toughness and elongation amounts were investigated by tensile tests under static loading with / without reinforced nanofiber mats. % 3 MWCNT reinforced N-6,6 nanofiber mats, tensile strength, E and toughness increased by 84.4, 235 and 112 %, respectively, when compared with N-6,6 nanofiber mats. In addition, scanning electron microscope (SEM) images were also investigated to determine the physical properties at the specification of reinforced /unreinforced N-6,6 nanofiber mats.
Jānis Grabis, Anita Letlena, Aija Krūmiņa
Solid State Phenomena, Volume 267, pp 93-97;

Zinc oxide nanoparticles doped with 0.2–1.5 mol% of Fe, Ni or Co and co-doped with 1 mol% of Ag were prepared by co-precipitation method and their photocatalytic activity in degradation of MB (methylene blue) water solution under ultraviolet irradiation was determined. X-ray diffraction analysis of the samples containing up to 0.5 mol% of iron group metals showed only ZnO and Ag phases. Crystallite size of doped ZnO nanoparticles was in the range of 27–31.6 nm depending on the sample composition and additional calcination at 400 °C. The photocatalytic activity of ZnO doped with iron group metals depended on the content of metals. The highest activity was observed for ZnO doped with 0.2 mol% of nickel. The co-doped with silver samples showed enhanced photocatalytic activity and higher reaction rate constant.
Lembit Kommel,
Solid State Phenomena, Volume 267, pp 229-233;

Wear of material in unlubricated sliding type electrical contact (e.g. contact wires for trolleys and rotor materials in electric engines and current generators) is one of the main failure causing modes of copper (Cu)-based alloys. High electrical conductivity, high tensile strength, suitable hardness and wear resistance under such conditions should be provided. In a present paper required properties of dispersion-hardened Cu-based electrical conductive alloy (Cu-0.68 wt. % Cr-0.02 wt. % S) were obtained by equal-channel angular press treatment with following six press treatments by Bc route and suitable heat treatment. The wear tests were carried out in unlubricated sliding pair with graphite disk. Optimal properties were reached after annealing at 450 °C for 1 h, exhibiting a lowest wear rate (~1.9268·10-9 g·m-1), high electrical conductivity (up to 95 % IACS) and Vickers microhardness up to 1.7 GPa, respectively.
Priit Kulu, Fransisco Casesnoves, Taavi Simson, Riho Tarbe
Solid State Phenomena, Volume 267, pp 201-206;

In this paper an attempt is made to use in wear prediction besides the wear from plastic and brittle components also fatigue fracture component. As example, WC-Co hardmetal reinforced composite hardfacing wear at abrasive impact erosion wear conditions was calculated at low and high impact energy, accountig microcutting with surface fatigue for the wear of matrix and brittle fracture, surface fatigue and plastic deformation for the wear of reinforcement. Calculated wear rates are compared with data obtained from experimental tests. The obtained results show that the used surface fatigue wear model is not applicable in the current case; the recommendations for the further improvement of the model are issued.
Solid State Phenomena, Volume 267, pp 63-67;

To create the heat-bonded geotextile with desirable properties, the mix of fibres (hemp, recycled polyethylene terephthalate and polypropylene fibres) for nonwoven webs formation and additional polypropylene reinforcing mesh are used. The results of the study on the influence of the reinforcing mesh on the properties of nonwoven composites (NWCs) are presented. Mechanical properties, water penetration and air permeability of the thermoplastic mesh reinforced NWCs depend on the hemp fibre pre-treatment time, mass per unit area and thickness of the used web and location of the reinforcing mesh. Obtained results allow concluding that mechanical as well as water penetration characteristics of the produced heat-bonded geotextiles are higher, while air permeability is comparable to the properties of the commercial prototype.
, Karlis Kalnins, Anita Zagorska, Juris Matvejs
Solid State Phenomena, Volume 267, pp 76-81;

One type of birch wood plywood by-product: plywood sanding dust (PSD) and recycled high density polyethylene (rHDPE) composites physical mechanical properties (tensile, flexural strength and modulus, impact strength and microhardness), water resistance and fluidity of the composite melts, were evaluated. These studies showed the possibility of the usage of presented by-product as an excellent reinforcement for recycled high density polyethylene matrix. It was observed that the modulus of the tensile for unmodified rHDPE+PSD composites increased up to 2.3 times, the modulus of flexural till 4 times, but the microhardness only 1.4 times. Optimal content of the PSD in recycled high density polyethylene composites could be 50 wt. %. As a coupling agent, the maleated polyethylene (MAPE) for modifying of the rHDPE+50 wt. % PSD composite was used. Due to the MAPE additives, the improvement (30-50 %) of the investigated exploitation properties was observed, but in comparison with unmodified composites the resistance of water increased up to 3.0 times. Optimal content of MAPE in rHDPE+50 wt. % PSD composition could be 3 wt.%.
Andrei Bogatov,
Solid State Phenomena, Volume 267, pp 185-189;

The nanocrystalline diamond films were deposited by microwave plasma enhanced chemical vapour deposition (PE-CVD) on Si (100) substrate. Reciprocating sliding tests were conducted using Si3N4 balls as a counter body. A method based on the construction of the Abbott curve representing the areas of pristine and worn surface in the wear scars was applied for estimation of the wear rate. The calculated wear rates were compared with the results obtained by profilometric measurements and direct measurement of the wear scars cross sections by scanning electron microscopy (SEM).
Solid State Phenomena, Volume 267, pp 17-22;

The synthesis technology of polyol from crude deciduous tree tall oil was developed, the structure of obtained polyol was analyzed using FTIR spectroscopy. Compositions of rigid polyurethane (PUR) foams were formulated using polyol from crude deciduous tree tall oil, Isocyanate indexes varied in wide range from 150 to 300. The densities of obtained rigid polyurethane foams was in range from 44-101 kg/m3. Produced rigid PUR foams were characterized by good compression characteristics and low water absorption. The optimal water absorption was achieved at density lower than 50 kg/m3 and Isocyanate index lower than 175. Thus the obtained PUR foams have the potential to be used for boat construction or for production of life-saving equipment.
, Nataliia Raksha, Lydmila Ostapchenko, Olena Mokrousova, Olga Andreyeva
Solid State Phenomena, Volume 267, pp 172-176;

The study presents the extraction of collagen, a product of high value, from fleshings form hides. After testing several collagen extraction procedures we have proposed the simple and effective method to extract collagen from collagen-containing wastes of the leather industry. The unified method is based on the extraction of collagen using acetic acid in the presence of EDTA and included two repeated extraction stages. Qualitative analysis of the collagen using the disk-electrophoresis method showed a different ratio of monomers, dimers and other proteins.
Harri Lille, Alexander Ryabchikov, Jakub Kõo, Eron Adoberg, Liina Lind, Liisa Kurissoo, Priidu Peetsalu
Solid State Phenomena, Volume 267, pp 212-218;

The aim of the study was to determine macroscopic residual stresses in Physical Vapor Deposits (PVD) coatings through measurement of the length variation of the strip substrates coated on both sides. The length change of the strip was reduced to the deflection of the middle cross-section of the elastic element and was recorded by four strain gauges. For validating the obtained results, the conventional curvature method was used. As an application, residual stresses in hard AlCrN PVD coatings were investigated. The coatings were nanolayered to achieve better coating toughness for blanking and punching applications. The steel strips and steel plates with two thicknesses were used as the substrate. The values of the compressive residual stresses, determined by both methods for the investigated coatings, were very high (3.3 -3.6 GPa) independent of coating thickness and practically equal within the measurement uncertainty of the method. Good agreement between the experimental results obtained with both methods suggests that the presented method, strip length variation, is applicable for determination of residual stresses in coatings. Compressive stresses in coatings are desirable as they strengthen the coating.
Solid State Phenomena, Volume 267, pp 58-62;

The fire performance of a geocement-based binder was investigated with a combination of analytical techniques, in terms of changes in composition and microstructure. Geocement, formulated as Na2O∙Al2O3∙6SiO2∙20H2O, was prepared using metakaolin, sodium water-glass, rotten stone and sodium hydroxide. The mixture was homogenized by passing through a hydrodynamic cavitator. Cubes of 20 mm were prepared, hardened at laboratory conditions for 28 days, and subsequently burnt at 600, 800 and 1200 °C in a laboratory furnace. Cavitation treatment resulted in a highly amorphous binder; amorphous fraction decreased upon firing up to 800 °C due to crystallization, and increased above 1000 °C because of melt formation. Porosity increased with firing temperature and pores larger than 1 mm in diameter prevailed at 1200 °C. The material remained stable up to 1200 °C. The results indicate the adequacy of this geocement-based binder for preparing fire-protecting materials.
, , , Stefan Klien, Alexander Diem, Jürgen Schmidt, Richard Tessadri,
Solid State Phenomena, Volume 267, pp 190-194;

Anodization of aluminum (Al) is a well-known process for the production of oxidized Al surfaces. Within the scope of the present work, three different Al-oxide layers, produced with different electrochemical methods, were investigated in view of their layer morphology and tribological properties. For this purpose, a newly developed PCO layer (Innovent e.V.), and two commercially available layers, Ematal and a CERANOD®, were compared. Al-oxide layers produced on flat samples were tested against cylindrical DIN 100Cr6 rings under dry sliding conditions. It was observed that under the selected conditions, the frictional behavior of the Al-oxide layers can be influenced by their structural composition and their surface topography, i.e. is different when their structure is amorphous or crystalline. The newly developed Al-oxide layer, which possesses the lowest surface roughness and a very uniform porosity, provided the longest lasting low friction period. Since γ-Al2O3 was also observed in this layer, it is believed that the structural composition of the Al-oxide layer has additionally influenced the frictional response of these samples.
Halima Ait Mahamed, Hakim Aguedal, Hafida Hentit, Abdelkader Iddou, Khaled Mekhissi, , Jean Claude Jumas,
Solid State Phenomena, Volume 267, pp 132-138;

This work presents the possible recovery and reuse, after treatment, of an iron-based sludge from wastewater treatment station in the removal of cadmium in aqueous solution. The sludge sustained a heat treatment (100 and 500°C) and was characterized by XRD, FTIR, BET and SEM witch shown an evolution in the morphology and the structure of the materials indicating the effect of the heat temperature. The material was then applied to remove cadmium in aqueous solution. The results show that the raw material gives the best results with a maximal adsorption capacity of 70.92 mg/g at pH=5.This study has shown us that it is possible to recover and reuse effectively sludge, from wastewater treatment plant, considered as a solid waste, in the removal of a pollutant such as cadmium in aqueous solution.
, Jüri Pirso, , Mart Viljus, Sergei Letunovitš
Solid State Phenomena, Volume 267, pp 162-166;

Present paper discusses the influence of spark plasma sintering (SPS) on the microstructure and perfomances of chromium carbide based cermets. The effect of SPS parameters (temperature, pressure) is discussed. It is shown that SPS enables to produce more fine grained chromium carbide based cermets compared to conventional liquid phase sintering. Hardness and fracture toughness are exhibited.
Olga Andreyeva, Anna Nikonova, Lesia Maistrenko
Solid State Phenomena, Volume 267, pp 98-102;

In natural leather production polymeric compounds are generally used during leather finishing coating. However, given that liquid processing is crucial for derma structure and properties development, we have identified the rationale for applying polymers based on maleic and acrylic acids during chrome and titanium tanning of garment leather by analysing specimens of polymer-mineral tanning. We have applied analysis techniques traditional for leather industry (strength of surface, strength and percentage extension, shrinkage temperature, moisture content, mineral substances content etc.), as well as mathematical statistics techniques, in order to do it. It has been established that structure and custom properties development of polymer-mineral tanning leather products has been improved as compared with pickle-chrome tanning ones.
, , Mārtiņš Kalniņš
Solid State Phenomena, Volume 267, pp 109-113;

Nail polish as a system used in cosmetics still faces stability issues. Pigment sedimentation and syneresis are the most common problems for solvent based systems. The scope of this research was to produce a working 'gel' dispersion for use as a suspension agent in nail polish systems. Various thixotropic agents (hectorite and bentonite clays and hydrophobic and hydrophilic silica grades) and methods (high shear homogenisation (HSH) and high pressure homogenisation (HPH)) were employed to affect this result. From the rheology results it is concluded, that the HPH ensures the development of the systems with the required viscosity recovery properties. It is also concluded that high shear developed systems with hydrophilic silica thixotropic agent are well suited for use as a suspension agent in nail polish formulations.
Kakur Naresh, Shankar Krishnapillai, Velmurugan Ramachandran
Solid State Phenomena, Volume 267, pp 87-92;

In the present work, the neat epoxy and different orientations [0°, 45°, 90°, (45°/-45°/45°) s, (±45°/0°/90°) s] of unidirectional carbon/epoxy composites are experimentally studied under tensile and impact loading. The notched impact tests are performed using the Izod impact machine to obtain the energy absorption of neat epoxy and different CFRP composites which is required for effective design of bullet proof jackets and military vehicles. The micro mechanical analysis is employed to determine the shear properties of a matrix using the tensile properties. Using classical laminate theory [CLT], the theoretical tensile properties are determined. The SEM fractography analysis is used to observe the damage mechanisms of neat epoxy and different orientations of CFRP composites subjected to tension and impact loading.
Piyasak Akcaboot, Napat Kanokpornwasin, Monthida Raoarun, Patraporn Saiwattanasuk, Pinsuda Viravathana
Solid State Phenomena, Volume 266, pp 117-121;

Co-promoted Cu/ZnO catalysts were studied for Fischer-Tropsch synthesis (FTS). All catalysts were prepared by the co-precipitation method, having the mass ratio of Co:Cu:Zn=0 (unpromoted), 0.05, 0.5:1:1, and characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). From XRD and XAS, the results confirmed the phase transformation of CuO to Cu foil and Co3O4 to Co foil in Co-promoted catalysts after reduction. After FTS reaction testing, the Co-promoted catalysts showed the decrease in methanol selectivity of 15 and 1.6% for 0.05Co-Cu/ZnO and 0.5Co-Cu/ZnO, respectively, and the increase in C5-C15 selectivity during 30 h of reaction.
Alexandr Shubin, , Andrey Stepashkin, Dmitriy Arkhipov, , ,
Solid State Phenomena, Volume 266, pp 207-211;

We report on preparation of Mg2(Si,Ge,Sn)-based thermoelectric materials by a direct induction melting method in Al2O3 crucible. A 40 g ingot of Mg2Si0.8Sn0.1Ge0.1 was prepared after addition to the batch 10 wt% of Mg excess. Evolution of crystal structure of the induction melted sample upon annealing and spark plasma sintering (SPS) was tracked by room-temperature X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. An evidence for the formation of Mg2(Si,Ge,Sn) solid solution was obtained from the crystal lattice parameter of this phase which was found to be larger than that of undoped Mg2Si. XRD and SEM indicated that alongside with the main phase of the Mg2(Si,Ge,Sn) solid solution, an impurity phase of Mg2Sn exists in the sample. Amount of the Mg2Sn impurity phase is significantly reduced in spark plasma sintered sample.
G. Korotcenkov, Vladimir Brinzari, , M.H. Ham, B.K. Cho
Solid State Phenomena, Volume 266, pp 187-195;

This article gives a brief description of metal oxides, acceptable for using in advanced conductometric gas sensors, as well as a consideration of approaches, that can be used to select metal oxides for the manufacture of devices intended to sensor market.
G.V. Nesvetaev, I.V. Korchagin, Y.Y. Lopatina
Solid State Phenomena, Volume 265, pp 109-113;

The relationship between the creep factor of concrete and hardened cement paste and the E-modulus of aggregate and evaluation of the effects of some modifiers on the creep factor of the hardened cement paste was determined. The influence of the SP on the creep factor of hardened cement paste is ambiguous: SP may increase, decrease, or not change the creep factor. The possible deviation of creep factor of hardened cement paste with the SP in certain cases can be up to 4 times. The average statistical increase in the creep factor of hardened cement paste may be 7 to 35%. The creep factor of regular concrete is equal 0.43 - 0.9 value of the creep factor of hardened cement paste. Superplasticizers may increase the creep of concrete up to 30% and in some cases - up to 3 times. Silica fume, metakaolin, white ash, including when used with the superplasticizers, may reduce the creep of concrete from 15 to 50%. An equation was suggested to calculate the E-modulus of concrete with the volume of hardened cement paste of 0.27 - 0.35 as a function of E-modulus of hardened cement paste and E-modulus of the aggregates.
Mahadi Sharif, Chew Sue Ping,
Solid State Phenomena, Volume 266, pp 283-286;

Carbon nanotube (CNT) acts as electromagnetic interference shielding material in concrete composites was presented in this paper. Three concrete samples respectively with different CNT contents were casted and experimentally tested their shielding effectiveness (SE). The SE measurements which were obtained in function of frequency were taken using vector network analyzer (VNA) in the frequency range of 2.4 - 4.0 GHz. The experimental results showed that the CNT contributes to change in conductivity due to the positioning of the electric field of the incident wave and thus, produces different shielding performances. The EMI SE of concrete composites is improved up to 41dB with CNT concentration of 1.5-2.0 wt%.
Kanuengnit Pongpat, , , Anak Khantachawana
Solid State Phenomena, Volume 266, pp 245-251;

Curved nickel-titanium (NiTi) orthodontic archwires are widely used in deep bite and open bite correction because of their extraordinary properties of shape memory and superelasticity. The aim of this study were to investigate the mechanical properties of curved NiTi archwires prepared by two different techniques; cold bending and direct electric resistance heat treatment (DERHT) bending and compare those properties to preformed curve NiTi archwires. Preformed curve archwires, 0.016x0.022 inch, were served as a control (group1). Plain archwires were curved into similar geometry as control by fingers (group2) and under the application of DERHT (group3). The three-point bending test was performed to analyze unloading force, springback and stiffness of archwires. Surface hardness was measured by Vickers micro-hardness test. The result showed that the unload force of all sample groups were similar. However, the stiffness and spring back properties of group2 and group3 were significantly higher than those of group 1(p<0.05). Moreover, surface hardness of cold forming technique and preform-curved NiTi archwire was slightly lower than those obtained from DERHT bending technique. Based on these results, the cold bending technique could provide the curved archwire with similar mechanical properties to the preform-curved NiTi archwire. Therefore, the cold bending technique was acceptable to be used as a chair-side orthodontic NiTi wire bending.
, , Rizki Hidayatullah, Gerra Maulana,
Solid State Phenomena, Volume 266, pp 238-244;

Generally, metal injection molding (MIM) method utilizes SS 17-4 PH as material for application of orthodontic bracket. One of the process of MIM is thermal debinding, which binder is eliminated by thermal energy. In this study, thermal debinding process is conducted with variation of temperature, i.e. 480, 510, and 540°C, holding time, i.e. 0.5, 1 and 2 hours, heating rate, i.e. 0.5, 1, 1.5, and 2°C/min.The effect of temperature shows that the increased temperature will result in the mass reduction percentage due to formation of oxide on the sample, which will be proven through TGA testing. The highest mass reduction was 6.4137 wt% which was obtained at 480°C. For the variation of holding time, the longer the holding time will result in increased mass reduction and the highest mas reduction was 6.255 wt% which was obtained during 2 hours of holding time. For the heating rate, the slower the heating rate will result in increased mass reduction and decreased the presence of crack formation. The best variable was obtained at heating rate of 0.5°C/min, which resulted mass reduction of 6.2488 wt% and less crack formation.
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