The glass-ceramic sealant materials obtained from basalt for SOFC

Ediz Ercenk,A. Elif Cicekli,Senol Yilmaz 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12

In the current study, utilization possibilities of the basalt based glass-ceramic as a sealant material for solid oxide fuel cell(SOFC) were investigated. Crushed, milled and sieved basalt powders were modified by some additives. The basalt powderand modified mixture were separately melted in alumina crucible and cast into water to obtain glass granules. These granuleswere milled, and exposed to heating microscopy and differential thermal analysis (DTA). Some parameters such as glasstransition and softening temperature were determined by these analyses. The powders were applied on the Crofer 22 APUinterconnector material, and heat treatment was carried out. The interface characteristics between the glass-ceramic layer andinterconnector were characterized using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Theresults showed that the basalt base glass-ceramic sealant material exhibited promising properties to use for SOFC.

Crystallization kinetics of mica glass-ceramic in the SiO2-Al2O3-MgO-K2O-B2O3-F2 System

Ediz Ercenk,Senol Yilmaz 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1

A mica glass-ceramic in the SiO2-Al2O3-MgO-K2O-B2O3-F2 glass system was prepared by a melting method. The crystallization behaviour and crystallization kinetics of a sample with glass-ceramic composition were examined. DTA and XRD analysis revealed the crystallization of phlogopite, fluorphlogopite, clinohumite and spinel phases. The activation energies for the precipitation of crystalline phases have been evaluated, and the crystallization mechanisms have been studied by applying DTA measurements performed at various heating rates. The results indicate that the growth of mica is a twodimensional process controlled by the crystal-glass interface reaction. The average calculated values of crystallization and viscous flow for the precipitation of crystal phases from the glass matrix were measured to be 289.9 ± 8 kJ/mol and 348.7 ± 14 kJ/mol, respectively. The mica glass-ceramics exhibited excellent performance in machinability tests without cracking or deforming.

Grain growth kinetics in the xAl2O3−6wt. % Bi2O3 − (94-x) ZnO (x = 0, 2, 4) ceramic system

Ediz Ercenk,Senol Yilmaz,H. Ozkan Toplan,Volkan Gunay 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

The effects of the amount of Al2O3 (0, 2 and 4 wt.%) on the microstructural properties have been studied in a binary ZnO-6 wt% Bi2O3 system. The microstructure of the samples consists mainly of ZnO grains with β-Bi2O3 and ZnAl2O4 spinel as the secondary phases. The grain growth kinetics in the 0, 2 and 4wt.% Al2O3 added ZnO-6wt.% Bi2O3 system were studied using the simplified phenomenological grain growth kinetics equation together with the physical properties of the sintered samples. The grain growth exponent value (n) and the apparent activation energy for the ZnO-6 wt.% Bi2O3 system were 5 and 218 kJ/mol, respectively. The addition of the Al2O3 to the ZnO-6 wt.% Bi2O3 system inhibited the ZnO grain growth. At 2 and 4 wt.% Al2O3 additions, the apparent activation energies were calculated as 341 and 578 kJ/mol respectively. The addition of Al2O3 to the system inhibited the grain growth of ZnO ceramics. The effects of the amount of Al2O3 (0, 2 and 4 wt.%) on the microstructural properties have been studied in a binary ZnO-6 wt% Bi2O3 system. The microstructure of the samples consists mainly of ZnO grains with β-Bi2O3 and ZnAl2O4 spinel as the secondary phases. The grain growth kinetics in the 0, 2 and 4wt.% Al2O3 added ZnO-6wt.% Bi2O3 system were studied using the simplified phenomenological grain growth kinetics equation together with the physical properties of the sintered samples. The grain growth exponent value (n) and the apparent activation energy for the ZnO-6 wt.% Bi2O3 system were 5 and 218 kJ/mol, respectively. The addition of the Al2O3 to the ZnO-6 wt.% Bi2O3 system inhibited the ZnO grain growth. At 2 and 4 wt.% Al2O3 additions, the apparent activation energies were calculated as 341 and 578 kJ/mol respectively. The addition of Al2O3 to the system inhibited the grain growth of ZnO ceramics.

The use of alunitic kaolin in the production of ceramic membrane support

Nezahat Ediz,Ilknur Tatar,Ahmet Aydın 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1

Although Turkey’s kaolin reserves are substantial, much of the reserves are of alunitic type and the largest deposit of this type is located in the Bal kesir-S nd rg Region. Alunitic kaolin cannot be used in ceramic industry owing to its sulphur content. Since alunite is disseminated within kaolin, it is difficult to remove it from kaolin by using mineral processing methods. In this research, alunite existence within the kaolin was used as an advantage in the production of ceramic membrane support since it allows for the occurrence of desirable homogeneous porosity. For this purpose, 3 different alunitic kaolin samples were taken from the Bal kesir-S nd rg Region and were comminuted. The materials obtained were shaped using dry pressing and slip casting methods to obtain ceramic membrane supports. The supports were sintered at 900 o C-1300 o C for 3 hours. The physical, mechanical and micro-structural properties of the sintered ceramic membrane supports were subsequently determined. The best porosity and strength results were obtained from SB1-1100 and PB1K-1100 coded supports which were made of K1 kaolin (having the highest alunite content).

Characterization of porcelain tile bodies with colemanite waste added as a new sintering agent

Nezahat Ediz,Arife Yurdakulb 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4

This research investigated the possible use of high boron oxide (B2O3) bearing solid waste, obtained during the enrichment of colemanite mineral (Ca2B6O11.5H2O), as an alternative sintering agent to Na-feldspar (NaAlSi3O8) in porcelain tile production. The chemical composition, mineralogical properties and behaviour under the heat treatment of solid colemanite waste were characterized in detail by the use of inductive coupled plasma (ICP), X-ray diffraction (XRD) and differential thermal analysis (DTA) / thermo-gravimetric analysis (TG). Physical-mechanical properties of standard and waste-added porcelain tile bodies obtained by sintering at 1210℃ (under factory conditions) such as green strength, dry strength, fired strength and water absorption were determined as a function of waste replacement for Na-feldspar. The sintering behaviour of waste-added porcelain tile bodies under fast firing conditions was also determined by an optical dilatometer and compared with that of standard porcelain tiles. The phases obtained in standard and waste-added porcelain tile bodies after sintering were determined by XRD analysis. The effect of these phases on microstructure and the relationships between physical-mechanical properties and the microstructure were also investigated through a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectrometery. After detailed phase studies and microstructural analysis together with the characterization of behaviour under heat treatment, it was discovered that colemanite waste had a high fluxing character and decreased the sintering temperature when used in porcelain tile recipes to replace Na-feldspar. It was also determined that factories using colemanite waste should work at lower sintering temperatures in order to obtain better physical-mechanical properties for porcelain tiles and to reduce energy costs. This research investigated the possible use of high boron oxide (B2O3) bearing solid waste, obtained during the enrichment of colemanite mineral (Ca2B6O11.5H2O), as an alternative sintering agent to Na-feldspar (NaAlSi3O8) in porcelain tile production. The chemical composition, mineralogical properties and behaviour under the heat treatment of solid colemanite waste were characterized in detail by the use of inductive coupled plasma (ICP), X-ray diffraction (XRD) and differential thermal analysis (DTA) / thermo-gravimetric analysis (TG). Physical-mechanical properties of standard and waste-added porcelain tile bodies obtained by sintering at 1210℃ (under factory conditions) such as green strength, dry strength, fired strength and water absorption were determined as a function of waste replacement for Na-feldspar. The sintering behaviour of waste-added porcelain tile bodies under fast firing conditions was also determined by an optical dilatometer and compared with that of standard porcelain tiles. The phases obtained in standard and waste-added porcelain tile bodies after sintering were determined by XRD analysis. The effect of these phases on microstructure and the relationships between physical-mechanical properties and the microstructure were also investigated through a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectrometery. After detailed phase studies and microstructural analysis together with the characterization of behaviour under heat treatment, it was discovered that colemanite waste had a high fluxing character and decreased the sintering temperature when used in porcelain tile recipes to replace Na-feldspar. It was also determined that factories using colemanite waste should work at lower sintering temperatures in order to obtain better physical-mechanical properties for porcelain tiles and to reduce energy costs.

Development of body formulations using colemanite waste in porcelain tile production

Nezahat Ediz,Arife Yurdakul 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

Porcelain tiles have become one of the most important products of the ceramic industry in the last decade mainly owing to their attractive physical and mechanical properties including high strength, high fracture toughness and density, excellent chemical resistance and low water absorption. The attractiveness of using porcelain has initiated intensive research work for alternative raw materials because of the depletion and the high cost of the usual materials currently used in the ceramic industry. In this research, the aim was to use boron-bearing solid wastes (Ca2B6O11.5H2O) as an alternative fluxing agent to Na-feldspar (NaAlSi3O8) in fast-fired porcelain tile bodies produced under industrial conditions without altering the microstructural, physical and chemical properties required from the final product. For this purpose, the suitability of the colemanite-added porcelain tile bodies to fast-firing conditions was determined using an optical dilatometer. It was then understood that a calcination process was needed in order to effectively use the waste in porcelain tile production. Therefore, the calcination process was applied to the colemanite solid waste before the waste-added bodies were sintered at 1210℃ and 1130℃. The results were compared with those of the standard porcelain tile bodies produced at the same sintering temperatures. After detailed phase analysis (XRD), microstructural examination (SEM-EDX) and physical-mechanical tests, it was found that the standard porcelain tile body produced at 1210℃ (R1) could be obtained at 1130℃ by adding 5% colemanite solid waste (by weight) to the standard tile body to replace Na-feldspar (R7). This result enables production of porcelain tiles at lower temperatures without changing the other operational parameters, only using colemanite waste as a new fluxing agent in the body formulations. Porcelain tiles have become one of the most important products of the ceramic industry in the last decade mainly owing to their attractive physical and mechanical properties including high strength, high fracture toughness and density, excellent chemical resistance and low water absorption. The attractiveness of using porcelain has initiated intensive research work for alternative raw materials because of the depletion and the high cost of the usual materials currently used in the ceramic industry. In this research, the aim was to use boron-bearing solid wastes (Ca2B6O11.5H2O) as an alternative fluxing agent to Na-feldspar (NaAlSi3O8) in fast-fired porcelain tile bodies produced under industrial conditions without altering the microstructural, physical and chemical properties required from the final product. For this purpose, the suitability of the colemanite-added porcelain tile bodies to fast-firing conditions was determined using an optical dilatometer. It was then understood that a calcination process was needed in order to effectively use the waste in porcelain tile production. Therefore, the calcination process was applied to the colemanite solid waste before the waste-added bodies were sintered at 1210℃ and 1130℃. The results were compared with those of the standard porcelain tile bodies produced at the same sintering temperatures. After detailed phase analysis (XRD), microstructural examination (SEM-EDX) and physical-mechanical tests, it was found that the standard porcelain tile body produced at 1210℃ (R1) could be obtained at 1130℃ by adding 5% colemanite solid waste (by weight) to the standard tile body to replace Na-feldspar (R7). This result enables production of porcelain tiles at lower temperatures without changing the other operational parameters, only using colemanite waste as a new fluxing agent in the body formulations.

Beneficiation of alunitic kaolin within the floor and wall tile angobe compositions

İlknur Tatar,Nezahat Ediz,Ahmet Aydın 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1

Most of the kaolin in Bal kesir-S nd rg (Turkey) region cannot be used in ceramic industry because of its high alunite content. The alunite within the composition of kaolin has to be removed in order them to be used in ceramic industry. Therefore, this research aimed at removing alunite from the kaolins of Balikesir-Sindirgi region and investigating its possible use in ceramic industry. For this purpose, mechanical scrubbing-screening, flotation and calcination methods were applied to the kaolins of the region to remove alunite. The material obtained was then used in the floor and wall tile angobe recipes of a ceramic tile factory. The angobes, prepared using the factory’s standard angobe recipes, were applied to the floor and wall tile bodies of the factory and later they were glazed. After the tests, it was understood that F2 angobe prepared by M2 kaolin, beneficiated through the flotation process and F3 angobe prepared by C3 kaolin, beneficiated through calcination could be alternatives for the commercial angobe currently used by the factory in floor tile production. Similarly, it was proven that W2 and W3 angobes prepared by using M2 and C3 kaolins, respectively, could be seen as alternatives for the angobe currently used by the factory in wall tile production.

Evaluation of intradermal absorbable and mattress sutures to close pilonidal sinus wounds with Limberg flap

Kenan Cetin,Hasan Ediz Sikar,Aytac Emre Kocao?lu,Muhammet Fikri Kunde?,Mehmet Karahan,Levent Kaptano?lu 대한외과학회 2018 Annals of Surgical Treatment and Research(ASRT) Vol.94 No.2

Purpose: We aimed to compare skin closure techniques, standard (intermittent mattress) and continuous subcuticular sutures, following Limberg flap procedure. Methods: From July 2013 to July 2015, 92 patients with sacrococcygeal pilonidal disease were prospectively randomized into 2 groups consisting of 46 patients for both. Patients underwent sinus excision and closure with Limberg flap; continuous subcuticular suture was used in subcuticular group (SG) and intermittent mattress sutures were used in mattress group (MG) for skin closure. Characteristics of patients, features of pilonidal disease, macerations, infections, wound dehiscence, flap necrosis, operation time, time of drain removal, wound complications, early recurrences, and time till return to work were compared between the 2 groups. Results: There was no statistical difference between groups per sex, age, body mass index, smoking, number of sinuses, depth of intergluteal sulcus, distance of incision to anus, volume of extracted tissue, number of hair follicles per ㎠, recurrence, operation, and mean follow-up time. Two patients showed signs of wound complications (4.4%) in SG, whereas 8 cases (17.4%) showed signs in MG (P < 0.05). One patient in SG had surgical site infection and required antibiotics (2.2%), whereas there were 6 cases treated in MG (13.0%) (P < 0.05). Removal of drain tube, and time till return to work rates are lower for SG than MG (P < 0.05). Conclusion: In conclusion, surgical procedures which include Limberg flap method and subcuticular closure may reduce infection and maceration rates. Future studies are needed to achieve greater detailed evaluation.

Low-Earth orbit satellite constellation for ADS-B based in-flight aircraft tracking

Nguyen, Thien H.,Tsafnat, Naomi,Cetin, Ediz,Osborne, Barnaby,Dixon, Thomas F. Techno-Press 2015 Advances in aircraft and spacecraft science Vol.2 No.1

Automatic Dependent Surveillance Broadcast (ADS-B) is quickly being adopted by aviation safety authorities around the world as the standard for aircraft tracking. The technology provides the opportunity for live tracking of aircraft positions within range of an ADS-B receiver stations. Currently these receiver stations are bound by land and local infrastructural constraints. As such there is little to no coverage over oceans and poles, over which many commercial flights routinely travel. A low cost space based ADS-B receiving system is proposed as a constellation of small satellites. The possibility for a link between aircraft and satellite is dependent primarily on proximity. Calculating the likelihood of a link between two moving targets when considering with the non-periodic and non-uniform nature of actual aircraft flight-paths is non-trivial. This analysis of the link likelihood and the performance of the tracking ability of the satellite constellation has been carried out by a direct simulation of satellites and aircraft. Parameters defining the constellation (satellite numbers, orbit size and shape, orbit configuration) were varied between reasonable limits. The recent MH370 disappearance was simulated and potential tracking and coverage was analysed using an example constellation. The trend of more satellites at a higher altitude inclined at 60 degrees was found to be the optimal solution.

Targeted surveillance to assess the presence of BSE in the age risk population of cattle slaughtered in Bursa, Turkey: preliminary results of an immunohistochemical detection study for the 2004-2005

M. Mufit Kahraman,M. Ozgur Ozygit,Ahmet Akkoc,Bulent Ediz,Deniz Misirlioglu,Gursel Sonmez,Aylin Alasonyalilar,Rahsan Yilmaz 대한수의학회 2007 JOURNAL OF VETERINARY SCIENCE Vol.8 No.2

Bovine spongiform encephalopathy (BSE), a member of the transmissible spongiform encepahlopathies, has been a notifiable disease in Turkey since 1997. In 2002, the BSE status of Turkey was assessed by the EU Scientific Steering Committee as “it is likely but not confirmed”.This study presents the results of a targeted surveillance study to assess the presence of BSE in the age risk population of Bursa, Turkey. In the assessment procedure, the immunohistochemical detection of protease-resistant prion protein (PrP-Sc) was aimed at and applied to 420 brain tissues of cattle slaughtered in Bursa at an age of 30-months and older. None of the samples were positive for BSE.