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1
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Microstructural Characterization and Thermal Properties of Aluminium Titanate/YSZ Ceramics

100%
Çitak E., Boyraz T.
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vol. 125
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issue 2
465-468
EN
Yttria stabilized zirconia (YSZ, with 3 mol.% Y_2O_3) has superior high temperature properties such as high tolerance for thermal shock, low thermal conductivity, mechanical properties, elevated melting point, good phase stability, and excellent oxidation resistance. Aluminium titanate (Al_2TiO_5) exhibits extremely good thermal shock resistance and low thermal conductivity coupled with good chemical resistance in molten metals. In the present work, aluminium titanate/YSZ ceramics with different percentages of Al_2TiO_5 was prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, dilatometer and hardness. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. The results revealed that the addition of aluminium titanate to YSZ matrix improves the properties of the aluminium titanate/YSZ ceramics.
2
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Effects of Na_2O/K_2O Ratio on the Deformation Behaviour of the Floor Tile Bodies

100%
Tamsu N., Vedat Bayrak A., Ozdemir H.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
283-284
EN
Floor tile bodies have excellent technical characteristics particularly as regards mechanical properties and frost resistance. Besides of these properties they could not have any deformation during firing. Considering floor tiles are generally fired in roller kilns, tiles are moving along the kiln carried by the rollers. It is possible that tiles can be bended by the roller movement because it is submitted to vertical forces due to its own weight. Pyroplastic deformation is the bending of a ceramic specimen caused by gravity during heat treatment. It can be defined as deformation or the loss of a shape of a product during its firing. Deformation behaviour of the tiles is related to liquid phases formed during firing or to a reduced viscosity of these phases. In this study, effects of altering SiO_2/Al_2O_3 ratio and Na_2O/K_2O ratio of the tile composition on the deformation behaviour of the floor tiles. Correlations between compositional change and deformation behaviour of the tile bodies will be also discussed in this presentation.
3
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The Effect of Boron Compound to Cement Hydration and Controllability of this Effect

100%
Davraz M.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2B
B-26-B-33
EN
The use of boron compounds as composites of cementitious, except for the limited usage conditions like setting retarder has not become widespread because of the hardening and the related problems. In this study, the effects of the boron compounds into hydration process of the different cement types and controllability of these effects was investigated. Portland cement, boron modified active belite cement, and calcium aluminate cement were used in the mortar mixtures as binder material. Except for the control mixture, boric acid (BA) was used at the ratios of 0.25-1.00% of weight of cement in mortar mixtures with Portland cement. Setting times dependent on pH, EC and T changes of fresh mortars were measured. With increasing BA concentration, setting times of the mortars rather increased, pH, electrical conductivity, and T values of the mortars significantly reduced. To suppress the affect of BA on the hydration process, the two various stabilizers were used in the mortars, setting times, pH, electrical conductivity, and T values of these mortars were measured again. As a result, the optimum workability times and the parameters of the hydration reaction taking into account, the most suitable type and usage ratio of stabilizer were determined for mortars with BA.
4
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Industrial-Scale Application of Characterization Techniques to Improve Surface Quality of Opaque Floor Tile Glazes

100%
Tunali A.
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vol. 125
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issue 2
667-668
EN
Improvement of surface quality of opaque floor tile glazes was the main purpose of this study. Opaque floor tile glaze was produced by mixing different frit compositions. Effects of softening point on glaze surface properties were investigated by thermal analysis. It was found that by increasing softening point of glaze composition surface defects can be solved and nanosized crystals similar to the wavelength of incident light can be achieved to obtain high opacity.
5
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Effect of B_2O_3/SiO_2 Ratio on Transparency of Anorthite Based Glass-Ceramic Glazes

100%
Tunali A., Selli N.
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vol. 125
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issue 2
511-512
EN
The present study was undertaken to determine the influence of B_2O_3/SiO_2 ratio on devitrification behaviour, anorthite crystal size and transparency of glass-ceramic glazes. Measurement by X-ray diffraction combined with scanning electron microscopy and energy dispersive X-ray spectroscopy microanalysis show that needle-like crystals of anorthite are formed. Sinterization and devitrification behaviour of system and viscosity change with temperature were analyzed by combining the datas that belong to differential thermal analysis and heating microscope analysis. Crystal size of anorthite was changed by modifying B_2O_3/SiO_2 ratio. It is confirmed that additional B_2O_3 prevents immediate phase separation during heat treatment in anorthite based glass-ceramic glazes.
6
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The Effects of Accelerating Admixture on the Mechanical Properties of Boric Acid Added Mortars

100%
Davraz M., Kılınçarslan Ş., Pehlivanoğlu E.
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vol. 125
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issue 2
263-267
EN
Use of boron compounds has not become widespread because of the hardening and the other related problems in cementitious composites. The boron compounds as an additive material can be used widely in the production of cement and concrete in case of the elimination of these negative conditions. Thus the control of workability and hydration process of fresh concrete and mortar, some technological properties such as fire resistance, the radiation impermeability of hardened concrete and mortars can be enhanced. In this study, the effects of accelerating admixtures to the mechanical properties of boric acid added mortars were investigated. In order to determine of these effects and the results obtained to compare with those of control mortars, prismatic mortar samples were prepared in accordance with TS 196-1. Boric acid was added to mortar samples by up to 1% from 0.25% by weight of cement. Boric acid was not added to control mortar samples. Portland cement, boron modified active belite cement and calcium aluminate cement as binding material were used in mortar samples. 2, 7, 28 day compressive strengths and 28 day flexural strengths of 315 prismatic samples which were prepared in accordance with the design of 35 different mixes were determined. Results of boric acid added mortar samples were compared with control samples produced by using Portland cement, BAB cement and CAC cement. 2, 7, and 28 day compressive/flexural strength of mortar samples which were added 1% boric acid was determined as 0/0, 12.8/2.90, 40/6 MPa, respectively. Other hand, 2, 7, and 28 day compressive/flexural strength of mortar samples which were added 1% boric acid and 2% sodium aluminate was determined as 14.2/3.07, 27.2/5.57, 34.2/5.97 MPa, respectively. As a result, the retarding effect of the boric acid in terms of early strength of concrete was suppressed using sodium aluminate.
7
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Microstructural Characterization and Thermal Properties of Aluminium Titanate/Spinel Ceramic Matrix Composites

100%
Önen U., Boyraz T.
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vol. 125
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issue 2
488-490
EN
Spinel (MgAl_2O_4) ceramics possesses a high melting point, high hardness, a relatively low density, excellent transmittance, a high strength, a relatively low thermal expansion coefficient, high thermal shock resistance and high chemical inertness. Aluminium titanate (Al_2TiO_5) exhibits extremely good thermal shock resistance and low thermal conductivity coupled with good chemical resistance in molten metals. In the present work, aluminium titanate/spinel ceramics composites with different percentages of Al_2TiO_5 were prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, dilatometer and hardness. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. Results revealed that the addition of aluminium titanate to spinel matrix improves the properties of the aluminium titanate/spinel ceramics.
8
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Role of the Quartz Particles on Stain Resistance of the Polished Porcelain Tiles

100%
Selli N., Tunali A.
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vol. 125
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issue 2
506-508
EN
In present study, effect of quartz particle size on microstructure and stain resistance of porcelain tiles were examined. Milling time was utilized as a main parameter to control residual quartz particle size. 12, 16 and 20 min milling time were used in a laboratory condition. As milling time increases, the particle size of residual quartz decreases. This reduction in the residual quartz particle size results in enhancement of the microstructure. When the microstructure contains irregular pores with high aspect ratio which are generally formed around the residual quartz in the body, stain resistance of the porcelain tiles decreases. Therefore, microstructural changes versus quartz particle size were investigated considering stain resistance of the polished porcelain tiles.
9
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Microstructural Characterization and Thermal Properties of Aluminium Titanate/Talc Ceramic Matrix Composites

100%
Ozsoy E., Onen U., Boyraz T.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1136-1138
EN
Talc (3MgO·4SiO₂·H₂O) has excellent mechanical properties, shock and abrasion resistance, good electrical and thermal shock resistance, softness, isolation, chemical activity, heat resistance and oil absorption properties. Aluminium titanate (Al₂TiO₅) exhibit extremely good thermal shock resistance and low thermal conductivity coupled with good chemical resistance in molten metals. In the present work, Aluminium titanate/talc ceramics composites with different percentages of Al₂TiO₅ was prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using XRD, SEM, dilatometer and hardness. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. Results, revealed that the addition of aluminium titanate to talc matrix improves the properties of the aluminium titanate/talc ceramics.
10
Content available remote

Microstructural Characterization and Thermal Properties of Aluminium Titanate/Porcelain Ceramic Matrix Composites

100%
Sacli M., Onen U., Boyraz T.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1133-1135
EN
Porcelain represents one of the most complex ceramics, formulated from a mix of clay, feldspar and quartz, sintered at temperatures between 1200°C and 1400°C, to form a glass-ceramic composite. Aluminium titanate (Al₂TiO₅) exhibits extremely good thermal shock resistance and low thermal conductivity, coupled with good chemical resistance in molten metals. In the present work, aluminium titanate/porcelain ceramics composites with different percentages of Al₂TiO₅ was prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using XRD, SEM, dilatometer and a hardness meter. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. The results have revealed that the addition of aluminium titanate to porcelain matrix improves the properties of the aluminium titanate/porcelain ceramics.
11
Content available remote

Characterisation of High Abrasion Resistant Commercial Glazes

100%
Tunali A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1243-1245
EN
In recent years high-abrasion resistance became industrially important for floor and porcelain tiles. Abrasive wear mechanism of commercial ceramic glazes were investigated by Scanning Electron Microscope, X-ray diffraction (XRD) and abrasion test using the PEI-visual evaluation technique. The study shows that anorthite is the main phase of commercial glazes, accompanied with quartz and corundum, and its properties are not good enough for high resistance. It is also observed that when mean free path of the anorthite phase decreases the wear resistance increases.
12
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Comparison of Radiation Properties of Tungsten and Additive Metal Coatings on 321 Stainless Steel Substrate

63%
Demir E., Karabas M., Sonmez S., Tugrul A., Ovecoglu M., Buyuk B.
Acta Physica Polonica A
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2017
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vol. 131
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issue 1
71-73
EN
In the present work, the gamma and neutron attenuation behaviors of tungsten, tungsten copper, and tungsten boron-carbide coatings on 321 stainless steel substrate were investigated against Cs-137 and Co-60 gamma radioisotopes and Pu-Be neutron source. The experimental results were compared and evaluated with pure 321 stainless steel to obtain gamma and neutron shielding properties of the coating materials. Tungsten, tungsten copper, and tungsten boron-carbide coatings on 321 stainless steel substrate were fabricated by atmospheric plasma spraying technique. Gamma and neutron transmission technique were used in this study to investigate the radiation behaviors of the coated materials. Linear attenuation coefficients of coated samples were carried out for Pu-Be neutron source. Transmittance values for each specimen were calculated at 0.662 MeV and 1.25 MeV gamma energies. The experimental results were evaluated for radiation shielding properties of the coated samples against gamma and neutron source with pure 321 stainless steel.
13
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Sintering Conditions for Al_2(WO_4)_3 High-Dense Ceramic

63%
Yordanova A., Koseva I., Nikolov V.
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vol. 125
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issue 2
567-570
EN
Al_2(WO_4)_3 nanoparticles with average particles size of 20, 90 and 200 nm are sintered by two methods: cold pressing with additional sintering at different temperatures and time durations and hot pressure sintering. Density, particles size dimensions and anisometricity are tested. The results show that optimal initial nanosized dimensions and an optimal pressing condition are needed to obtain compact ceramic. Hot pressure method gives possibilities of a ceramic with a density in order of 99.8% to be received, which possesses some level of transparency.
14
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Sintering Behaviour of ZnO:Cu Ceramics Fabricated by Sol-Gel Derived Powders

63%
Bahşi Z., Oral A., Aslan M., Kayahan E., Ozer M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
271-273
EN
Doped zinc(II) oxide (ZnO:Cu) ceramics were prepared from sol-gel derived nanocrystalline powders. Powders were prepared by dissolving zinc and copper acetates in isopropyl alcohol. Ethanolamine was used to enhance the solubility of acetates. Powders were produced by the calcination of the dried gels at 750°C. The crystal size of the undoped powders were uniform and around 50 nm while grain size of Cu doped powders varied between 0.3 and 2 μm. X-ray mapping of the powders showed that Cu was not homogeneously distributed and some particles had higher Cu content. After pressing of the powders, both doped and undoped ceramics were sintered at 1200C for 2 h. Microstructure of the Cu doped ceramics showed that Cu atoms partially dissolved in ZnO matrix and the rest formed a second phase in the grain boundaries. Average grain size of the ZnO:Cu ceramics was around 30 μm. Relative densities of the ceramics increased from 0.695 to 0.857 by Cu doping.
15
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An Investigation on the Mass Attenuation Coefficients of W-VC-C and W-VC-TiC-C Composites for Gamma Radioisotopes

63%
Tuğrul A., Demir E., Yılmaz O., Sönmez S., Öveçoğlu M., Büyük B.
Acta Physica Polonica A
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2016
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vol. 129
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issue 4
724-727
EN
In this study, tungsten-vanadium carbide-graphite and tungsten-vanadium carbide-titanium carbide-graphite composites (W-VC-TiC-C) which can be used in high-tech equipment were investigated against different gamma radioisotopes. The composite materials were produced via mechanical alloying method in two groups; one of them includes 93% tungsten (W), 6% vanadium carbide (VC) and 1% graphite (C) which was synthesized during three different alloying times (6, 12, 24 hours). Other group of the samples were composited as 91% tungsten, 6% vanadium carbide (VC), 2% titanium carbide (TiC) and 1% graphite (C) which has also three different alloying times (6, 12, 24 hours). Gamma transmission technique was used in the experiments to investigate the gamma attenuation properties of the composite materials. Linear and mass attenuation coefficients of the samples were determined in the experiments and theoretical mass attenuation coefficients were calculated using widely acknowledged XCOM computer code. The experimental mass attenuation coefficients and calculated theoretical results were compared and evaluated with each other. Results showed that gamma attenuation coefficients of the composite materials dependent on alloying time. It can be concluded that increasing the tungsten ratio causes higher linear attenuation coefficient which decreases with increasing gamma energies.
16
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Physical Characterization of Turbot (Psetta Maxima) Originated Natural Hydroxyapatite

51%
Inan A., Komur B., Ekren N., Aydogdu M., Gokce H., Ficai A., Salman S., Oktar F., Gunduz O.
Acta Physica Polonica A
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2017
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vol. 131
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issue 3
397-399
EN
Nowadays hydroxyapatite is one of the most popular biomaterials, which is used in various medical and dental applications areas as graft material. Bovine bone is the biggest source for natural hydroxyapatite production, but its production can lead to very dangerous disease, like mad cow disease, without high degree calcination. Hydroxyapatite produced from marine sources is much safer and easier to produce than bovine hydroxyapatite. Here in this study natural hydroxyapatite and related phases were produced from a local source turbot (Psetta maxima). Beside the main bony internal structure, there are koshers (cycloid scale) on its skin. Koshers are bulky bumps, looking like flat, small and rounded structures. Internal bones and those bulky bumps were cleaned from flesh with chemicals and calcined at 850°C for 4 hours. After calcinations, especially those bulky bumps, were formed into mesoporous structures with very light bluish color. Those mesoporous structures can be used as natural mesoporous hydroxyapatite structures for bone grafting purposes. The internal bones have also formed hydroxyapatite. Scanning electron microscope and X-ray diffraction studies were performed. I this study it is found that the bones of turbot consist of hydroxyapatite and TCP related phases. The aim of this study is to produce natural hydroxyapatite structures from turbot scale with low carbon footprint, without harming the environment and without using complex chemicals.
17
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Multilayer Perovskite-Based Thermistors Fabricated by LTCC Technology

51%
Kulawik J., Szwagierczak D., Witek K., Skwarek A., Gröger B.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
436-438
EN
In this work, single-phase La_{0.7}Sr_{0.3}Zr_{0.5}Co^{2+}_{0.2}Co^{3+}_{0.3}O_3 and La_{0.8}Sr_{0.2}Ti_{0.5}Co^{2+}_{0.3}Co^{3+}_{0.2}O_3 ceramics with the stable perovskite structure were utilized for fabrication of multilayer negative temperature coefficient thermistors. The number and thicknesses of ceramic layers were adjusted to attain suitable resistances in a desired temperature range. Scanning electron microscopy studies revealed a dense, fine-grained microstructure of ceramic layers, lack of delaminations and cracks at ceramic layer-conductive layer boundaries and a good cooperation with conductive layers. The temperature coefficients of resistance of the fabricated multilayer thermistors were changing from - 13 to - 1%/K in the temperature range from - 55 to 400C.
18
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Elasticity Study of PAAm-κ C Composite Prepared in Various κ C Content and Measured at Several Temperatures

51%
Evingür G., Pekcan Ö.
Acta Physica Polonica A
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2015
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vol. 128
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issue 3
331-335
EN
Polyacrylamide (PAAm)-kappa carrageenan (κC) composite gels were prepared via free radical crosslinking copolymerization with various (w/v) percentages of κC in the range between 0.5 and 3 (w/v)% of κC. Elasticity properties such as stress, strain and compressive elastic modulus, S of these composite gels were studied in various κC content and at several temperatures. The content and temperature dependence of the compressive elastic modulus, S of the swollen PAAm-κC composite gels due to volume phase transition were produced by using tensile testing technique. It is understood that the compressive elastic modulus was found to decrease up to 1 (w/v)% of κC, and then increase by increasing κC contents, at constant temperatures. The composite preserves the ability to undergo the volume phase transition and its compressive elastic modulus is found to be strongly dependent on the κC content and temperature. It is observed that the compressive elastic modulus increased when temperature is increased up to 40°C and then decreases below this temperature for all composite gels. However, PAAm-κC composite gel presented lower values for the compressive elastic modulus, showing a minima at 40°C for 1 (w/v)% of κC content gel.
19
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Phase Transformation and Sintering of Algeria Clay Powder

51%
Beddiar L., Sahnoune F., Heraiz M., Redaoui D.
Acta Physica Polonica A
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2017
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vol. 131
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issue 3
566-568
EN
Clay is one of the most used natural materials in the ceramic industry with various applications such as pottery, tiles, cement and bricks. The latter are used as a building material because of their excellent thermal and mechanical properties. In the present study, Algerian clay from Al-maathed area, M'sila district, was used to prepare bricks. The chemical composition of the clay was determined using X-ray fluorescence. Firing of clay was carried out in the temperature range 20-1000°C, at different heating rates. The present phases and their transformations, the activation energy, and the sintering mechanism were evaluated using X-ray diffraction, differential thermal analysis, thermogravimetric analysis and dilatometry. The activation energy for the sintering mechanism obtained from non-isothermal treatments is 420 kJ/mol. The value of the Avrami exponent, n, is determined from the shape of the crystallization exothermic dependence. It is related to m parameter (a numerical factor which depends on the dimensionality of crystal growth) obtained by Matusita method. Both of which are about 1.2 for clay sintering. These values indicate that bulk nucleation is dominant in clay sintering by three-dimensional growth, with polyhedron-like morphology controlled by interface reaction.
20
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The Effect of Calcination Temperature on the Electrochemical Performance of ZnO Coated LiMn_2O_4/MWCNT Nanocomposite Cathodes

51%
Akbulut A., Cetinkaya T., Guler M., Akbulut H.
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vol. 125
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issue 2
331-334
EN
In this study, it is aimed to develop LiMn_2O_4/MWCNT nanocomposite cathode materials by using different calcination temperatures (300, 500, 700°C). The aim of using MWCNTs in the active material is to overcome poor conductivity and to increase stability of the electrodes during charging and discharging. The nanocomposites were produced by sol-gel method, which allows producing very fine particle size of LiMn_2O_4. LiMn_2O_4 and LiMn_2O_4/MWCNT were uniformly coated on an Al-foil to obtain 500 μm thicknesses with a specific amount of binder and conducting agent. The surfaces of cathodes were coated with ZnO by using magnetron sputtering PVD with a thickness of 10 nm. Coin-type (CR2016) test cells were assembled, directly using the LiMn_2O_4/MWCNTs and surface coated LiMn_2O_4/MWCNTs as anode and a lithium metal foil as the counter electrode.
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