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Ankara Yıldırım Beyazıt University | AYBU · Department of Materials Engineering

Functionally graded ceramic systems consisted of Al2O3/(Al2O3–ZrO2) and Al2O3/(Al2O3–Nd2Ti2O7) have been produced by gel casting. In Al2O3/ZrO2 systems, Al2O3 was gathered with three different Al2O3/ZrO2 mixtures with varying ZrO2 contents. For Al2O3/Nd2Ti2O7 system, Al2O3 layer was combined with 3 mol% Nd2Ti2O7‐doped Al2O3. All samples sintered at...

Flame-retardant behavior of flax fabric coated by calcium borate powders with clove-like and elongated morphologies was investigated by thermal analysis and cone calorimeter. PDA was used to form strong and uniform adhesion of calcium borate onto fabric. Thermal analysis showed a 20% of decrease in mass loss, while detected exothermic/endothermic p...

The present study aimed to examine the effect of pH and time on the final morphology of calcium borate powders. Primarily, aqueous solutions that mainly consisted of borax and calcium chloride were prepared with five different pH values varying between 2 and 15. Hydrothermal synthesis temperature was determined as 200°C, and four different times fr...

Abstract The biocompatibility of silicon nitride ceramics was proven by several studies however this study is apart from the literature in the manner of production routes that are tape casting and partial sintering. We report the tape casting route was chosen and a porous structure was obtained by partial sintering technique. Tape casting brought a...

Si 3 N4 porous beads were produced from direct carbothermal reduction and nitridation of spheres composed of carbon+SiO 2 mixtures. A simple one-step sol-gel templating technique was used to prepare carbon+SiO 2 (molar ratio of carbon/SiO 2 was set as 4) containing spheres with a diameter of 2 mm. A natural and abundant biopolymer, alginate, is use...

Silicon nitride (Si3N4) is one of the promising ceramics for dental restoration due to providing significant benefits during the application. This study aimed to investigate the potential use of Si3N4 for all-ceramic dental restorations by characterizing some critical properties as color shade, mechanical resistance, shear-bond strength and radiolu...

Calcium orthophosphate (COP) ceramics have been investigated as bone repair materials for many decades. The first in vivo application of these materials was accomplished in 1920 to test tricalcium phosphate performance as a bone substitute. Since this first attempt, various COPs were investigated on animals to shed light on their effect on the heal...

Si3N4 ceramics show excellent characteristics of mechanical and chemical resistance in combination with good biocompatibility, antibacterial property and radiolucency. Therefore, they are intensively studied as structural materials in skeletal implant applications. Despite their attractive properties, there are limited data in the field about in vi...

Zircon (zirconium silicate; ZrSiO4) is an essential compound of sanitaryware glaze due to contributions to the final properties of the surface. In this study, the effect of zircon particle size on the surface properties (microstructural development, opacity, roughness, hardness and bacterial activity) were studied. Initially, zircon powder was mill...

Highly porous SiC ceramics containing borax decahydrate were produced by a starch consolidation method in which corn starch was used as a shaping and pore-forming additive. Four different compositions were prepared with different SiC:borax decahydrate ratios and corn starch content. Mixtures with a solid ratio of 55 wt.% were cast in non-porous mol...

The recycle rate of waste flat glass is quite low in spite of higher SiO2 content and its pre‐melted characteristic. This study searched a novel approach for the fabrication of Si3N4 powder by carbo‐thermal reduction and nitridation from waste glass. For comparison, starting powder mixtures were prepared from silica and waste SLS (soda‐lime‐silica)...

In this study, Si3N4 foams are successfully produced by a combination of replica and carbothermal reduction and nitridation (CRN) methods. Slurries prepared from C, SiO2 (molar ratio of C:SiO2 was kept to 2.2), bentonite and three types of oxide additives (Y2O3, CeO2 and Yb2O3) are impregnated into polyether sponges. With the addition of bentonite,...

Al2O3 ceramics with graded porosity were produced by using corn starch and PMMA sphere as pore former additives (PFA). Graded porosity was obtained by uniaxially pressing the stacks of Al2O3 mixtures with and without PFA together. Pressed samples were heat-treated to remove PFAs at 600oC and sintered at 1540oC. Final porosity of graded ceramics pro...

The phase and pore evolution of porcelain tiling against sintering temperature are investigated in this study. A standard porcelain tile composition was sintered at nine different temperatures between 1150 and 1230 °C. The amount of the amorphous phase and the degree of densification show good compatibility with each other; up to 1200 °C they incre...

The corrosion behavior of zircon containing glass-ceramic glazes was studied by examining four different glaze compositions. Glazes with different SiO2 and ZrO2 contents were prepared. Chemical resistance of glazed surfaces was tested by immersion of glazes in strong acid solution (HCl-18 vol.%). XRD studies of the surfaces before and after immersi...

Silisyum nitrür oksit dışı bir malzeme olduğu için kontrollü atmosfer koşullarında (argon, azot veya vakum ortamı) sinterlenmesi gerekmektedir. Bu durum hem maliyetin yük-sek olmasına, hem de ticari olarak üretim sürecinde işletmeler için ekstra makine teçhizat ve sarflara (atmosfer kontrollü fırın, sürekli gaz tedariği veya özel vakum pompaları) g...

Purpose: Study aims to investigate the elastic properties of porous Si 3 N 4 thus three different starch type as pore former additives were used to obtain different pore characteristics. Design/methodology/approach: Porous Si 3 N 4 ceramics were fabricated by partial sintering and pore former addition. Pore formers consisted of elliptic, round and...

•We produce highly porous (up to 66%) Si3N4.•We enhance the permeability of Si3N4 by using starch as pore former.•Increasing starch amount (≥20vol.%) created large and bimodal pore channels and permeability values of these samples are quite higher.•Pore size is more predominant than porosity on permeability. In this study, the possibility of enhanc...

Porous β-Si3N4 ceramics with two distinct structures were produced by using two different Si3N4 sources to investigate the relationship between microstructure and permeability. Results showed that regardless of pore amount, size of pore channels, shape-distribution of β-Si3N4 grains are more effective on permeability of porous Si3N4 ceramics. Highe...

Thermal properties of AlN.Si.Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 micron meter. In spite of sub-micron grain size, composites showed relative...

In this study, porous -Si 3 N 4 ceramics containing limited amount of Sm 2 O 3 and CaO as sintering aids were produced by addition of potato starch (10 and 20 vol.%) and partial sintering. Two different Si 3 N 4 powders, -and -, were used as starting materials. Scanning electron microscopy investigations revealed that development of elongated -Si 3...

In this study, porous -Si 3 N 4 ceramics containing limited amount of Sm 2 O 3 and CaO as sintering aids were produced by addition of potato starch (10 and 20 vol.%) and partial sintering. Two different Si 3 N 4 powders, -and -, were used as starting materials. Scanning electron microscopy investigations revealed that development of elongated -Si 3...

Cordierite ceramics were produced by using local magnesium sources. Mixtures were sintered at different temperatures to examine formation of cordierite. α-cordierite was formed as a major phase over 1150°C. High bulk density and nearly zero apparent porosity were achieved at 1200°C by using Mg-rich local clay as a magnesium source. Thermal expansio...