scholarly journals Impact of sintering conditions and zirconia addition on flexural strength and ion conductivity of Na-β”-alumina ceramics

2020 ◽  
Vol 23 ◽  
pp. 101118
Author(s):  
Marie-Claude Bay ◽  
Meike V.F. Heinz ◽  
Cristina Linte ◽  
Alexander German ◽  
Gurdial Blugan ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Ion Conductivity ◽  
Alumina Ceramics ◽  
Sintering Conditions ◽  
Zirconia Addition

Ion Conductivity of Nasicon Ceramics: Effects of Texture and Doping With B203 and A12 O3

1988 ◽  
Vol 135 ◽  
Author(s):  
Jakob W. Høj ◽  
John Engell
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Bulk Composition ◽  
Comparison Method ◽  
Ion Conductivity ◽  
Room Temperature Resistivity ◽  
Alumina Ceramics ◽  
History Of ◽  
Sintering Conditions ◽  
Temperature Resistivity

AbstractThe Nasiconss, Na1+XZr2SiXP3Xo12 O<X<3, includes some of the best solid state sodium conductors known today. Compositions in the interval 1.6<X<2.6 show conductivities comparable to the best aβ-alumina ceramics. It is well known that the ion conductivity of 8-alumina is strongly dependent on the texture of the ceramic. Here a similar behaviour is reported for Nasicon ceramics. Ceramics of the bulk composition Na2.94 Zr1.49Si2. 20P0.80O10.85 were prepared by a gel method. The final ceramics consist of Nasicon crystals with X=2.14 and a glass phase. The grain size and texture of the ceramics were controlled by varying the thermal history of the gel based raw materials and the sintering conditions. The room temperature resistivity of the resulting ceramics varies from 3.65 103 ohm cm to 1.23 10 ohm cm. Using the temperature comparison method and estimates of the area of grain boundaries in the ceramics, the resistivity of the Nasicon phase is estimated to be 225 ohm cm at 25°C. B203 - or Al2O3 -doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts.

Study on Alumina Ceramics for Dechlorinating Reactor Lining

2008 ◽  
Vol 368-372 ◽  
pp. 707-709
Author(s):  
Shi Gang Long ◽  
Feng Cao ◽  
Liu Heng Sun ◽  
Qing Min Meng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Spectral Analysis ◽  
Thermal Shock ◽  
Energy Dispersive ◽  
Alumina Ceramics ◽  
Sintering Conditions ◽  
Sintering Condition ◽  
Scanning Electron

Al2O3 ceramics samples were prepared by changing the ingredient and sintering conditions. The resistance experiment of the Al2O3 ceramics to hydrochloride corrosion and thermal shock were carried out, and then identified by means of scanning electron microscopy and energy dispersive spectral analysis. The results indicated the optimal Al2O3 and sintering condition for the dechlorinating reactor.

Evaluation of Thermal Shock Resistance of Alumina Ceramics

2011 ◽  
Vol 492 ◽  
pp. 333-336
Author(s):  
Kai Li ◽  
Lu Cun Guo
Keyword(s):  
Flexural Strength ◽  
Thermal Shock ◽  
Temperature Difference ◽  
Thermal Shock Resistance ◽  
Alumina Ceramics ◽  
Sharp Drop ◽  
Quenching Temperature ◽  
Before And After ◽  
Shock Resistance ◽  
Thermal Shock Behavior

The thermal shock behavior of alumina ceramics tested by two different approaches, water and air quenching, using an automatic experimental set was investigated. The changes of the flexural strength before and after the thermal shock was measured and used as an indicator of thermal shock resistance. The study reveals that air quenching test has limited impact on the changes of flexural strength, whereas the water quenching yields considerable decreases of the strength. The alumina ceramics was quenched in water at various temperature differences for five cycles. It is shown that the retained strength of the quenched specimens decreases abruptly at the temperature difference of 300°C, which indicates a great severity of thermal shock in this point. The thermal shock behavior of the specimens is evaluated by quenching in water as three different temperature differences, ΔT, setting at 300°C, 600°C and 800°C, respectively. The results show, for three different ΔT quenches, the strength reductions caused by the quenching exhibit similar trends: After a sharp drop, the residual strength remains almost unchanged at a certain level for each given quenching temperature difference, and the turning points all fall in the very first five to ten thermal cycles range. And the rank of the damage severity of alumina ceramics among the three different temperature differences is: ΔT800°C > ΔT600°C > ΔT300°C

Effect of Different Composite Additives on Thermal Conductivity of Corundum Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 500-504 ◽  
Author(s):  
Xing Yong Gu ◽  
Shao Ling Wu ◽  
Ai Hua Zhang ◽  
Ting Luo ◽  
Yun Xia Chen
Keyword(s):  
Thermal Conductivity ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Alumina Ceramic ◽  
Inorganic Materials ◽  
High Thermal Conductivity ◽  
Alumina Ceramics ◽  
Composite Ceramics ◽  
Subsequent Reaction ◽  
X Ray

To improve the thermal conductivity of alumina ceramics, different inorganic materials such as AlN, BN, Si3N4 and SiC which own high thermal conductivity were integrated with 96% alumina ceramic. The effect of addition of AlN, BN, Si3N4 and SiC on water absorption, flexural strength and thermal conductivity of the as-prepared alumina-based composite ceramics were investigated. Field emission scanning electron microscopy (FESEM) and X-ray diffractometer (XRD) were employed to characterize the microstructure and phase compositions of the composites. The results showed that sintering temperature of 96% alumina ceramic matrixes were improved in varying degree due to adding AlN, BN, SiC and Si3N4. A small quantity of Al6Si2O13 crystals were formed in the case of adding Si3N4 and SiC, which is due to the oxidation of Si3N4 and SiC into SiO2 in the air and the subsequent reaction with alumina. At appropriate firing temperature, the flexural strength of the composites with the addition of AlN is the best and higher than corundum matrixes. Meanwhile, the thermal conductivity of the composites with AlN has 110% improvement. It is obvious that AlN with high thermal conductivity is suitable for improving the thermal conductivity of corundum ceramics.

scholarly journals Modification of Porous Alumina Ceramics with Bioinert and Bioactive Glass Coatings

2008 ◽  
Vol 32 ◽  
pp. 211-214 ◽  
Author(s):  
X. Miao
Keyword(s):  
Bioactive Glass ◽  
Porous Alumina ◽  
Porous Ceramics ◽  
Glass Layer ◽  
Alumina Ceramics ◽  
Tissue Replacement ◽  
Porous Biomaterials ◽  
Porous Bioceramics ◽  
Pu Foams ◽  
Zirconia Addition

Porous biomaterials including porous bioceramics play important roles for hard tissue replacement and regeneration. I this paper, porous alumina (with and without zirconia addition) ceramics were produced via coating polyurethane (PU) foams with Al2O3 (ZrO2) slurries, followed by drying at room temperature and sintering at 1300 oC. The advantage of the PU foam method was the achieved high pore interconnectivity, but the mechanical properties of the porous ceramics were rather poor due to the high macroporosity and the high microporosity. To remove the microporosity and strengthen the porous alumina ceramics, a lanthanum-modified aluminosilicate (LAS) glass was used to infiltrate the alumina struts. Nevertheless, the resulting LAS-modified macroporous alumina ceramics would have no ability to bond to bone tissues. To impart a bioactivity (i.e. the ability of bone bonding) to the bioinert porous ceramics, a bioactive glass layer was applied by dipping with the bioactive glass slurry and sintering at 1200 oC. The twice coated porous alumina ceramics would exhibit high compressive strengths, allow bone tissue ingrowth, and form strong bonematerial integration. A biodegradable filler – calcium phosphate cement was also incorporated. A possible application of the porous bioceramics would be for the maxillofacial reconstruction.

Effect of Nano-Scale TiN on the Mechanical Properties and Microstructure of Si3N4 Based Ceramic Tool Materials

2006 ◽  
Vol 315-316 ◽  
pp. 154-158 ◽  
Author(s):  
Bin Zou ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Bing Qiang Liu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Ceramic Tool ◽  
Si3n4 Ceramic ◽  
Tool Materials ◽  
Nano Scale ◽  
Sintering Conditions ◽  
Si3n4 Matrix

An effect of nano-scale TiN grains on the mechanical properties and microstructure of Si3N4 based ceramic tool materials is investigated at the different sintering temperature. Compared to monolithic Si3N4 ceramic tool materials, the sintering temperature is decreased and mechanical properties is enhanced when only one percent of nano-scale TiN in term of mass is added into the Si3N4 matrix. The optimum mechanical properties are achieved when Si3N4/TiN nanocomposites tool materials were sintered at the sintering conditions of 1650, 30MPa and holding time of 40min. The flexural strength, fracture toughness and hardness are 1018.2MPa, 8.62MPa⋅m1/2 and 14.58GPa respectively. SEM micrographs indicate that microstructure is composed of the elongated and equiaxed β-Si3N4 grains, and some nano-scale TiN grains are enveloped into matrix grains.

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