Effects of Adding Form of Additives on the Structure and Properties of High-Purity Alumina Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1130-1132
Author(s):  
Qiang Ren ◽  
Xiu Lan Wu ◽  
Xuan Meng He
Keyword(s):  
High Purity ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Normal Pressure ◽  
The Body ◽  
Raw Material ◽  
Sintering Process ◽  
Alumina Ceramics ◽  
Dry Pressing ◽  
Α Al2o3

High-purity alumina ceramics was prepared using high-purity α-Al2O3 powder as raw material, nitrates or oxides of magnesium, chromium and copper as additives by a wet ball milling with a later dry pressing forming and normal pressure sintering process. The influence of additives on the sintering temperature, microstructure and bending strength of the prepared alumina ceramics was studies. The results showed that the additive doped with nitrate can be dispersed uniformly in the body with molecule scale, and the oxides obtained by decomposing of nitrates have the higher reactivity. Thus, the nitrate additives have better capacity than oxide additives in reducing the sintering temperature and inhibiting the abnormal grain growth, and the alumina ceramics prepared by adding of nitrate additives have higher density and bending strength.

Adsorption-Desorption Performances of Humidity Controlling Diatomite-Based Ceramics

2014 ◽  
Vol 1058 ◽  
pp. 200-204
Author(s):  
Xiao Su Cheng ◽  
Zhi Li ◽  
Hui Wang ◽  
Ping An Liu ◽  
An Ze Shui ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Molding Process ◽  
X Ray ◽  
Process Effects ◽  
Dry Pressing ◽  
Humidity Chamber ◽  
Adsorption Desorption ◽  
Electronic Microscope

The humidity controlling materials using diatomite as the major raw material were prepared by dry pressing molding process. Effects of various diatomite contents and sintering temperatures on the final products were investigated. The samples were also characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), and then tested adsorption-desorption performances by temperature and humidity chamber. The results indicate that the equilibrium moisture adsorption reaches to 338 g/m2 when diatomite content is fixed at ~70% and sintering temperature is holding at 1050°C, respectively.

PREPARATION OF Bi2O3-DOPED NiO/YSZ ANODE MATERIALS FOR SOFCs

2017 ◽  
Vol 24 (07) ◽  
pp. 1750092 ◽  
Author(s):  
FEI LI ◽  
JINGDE ZHANG ◽  
JUNPENG LUAN ◽  
YALEI LIU ◽  
JIANXUN HAN
Keyword(s):  
Weight Loss ◽  
Open Porosity ◽  
Anode Materials ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Sintering Aids ◽  
Dry Pressing ◽  
Sintering Properties ◽  
Cubic Structure ◽  
The Cost

The NiO/YSZ anode materials of SOFCs with Bi2O3 as sintering aids were successfully prepared by dry-pressing process. The effects of Bi2O3 content on the sintering properties of NiO/YSZ anode materials were studied, including the effects on the density, open porosity, weight loss, phase composition, microstructure, mechanical strength and electrical conductivity. In particular, the weight loss, relative density and bending strength of the sintered NiO/YSZ ceramics increased with the increase of Bi2O3 content while the open porosity decreased gradually. The density of the NiO–YSZ ceramics with 6[Formula: see text]wt.% Bi2O3 sintered at 1250[Formula: see text]C could reach that of the ceramics without Bi2O3 sintered at 1400[Formula: see text]C. For Bi2O3 concentration higher than 6[Formula: see text]wt.%, phase transformation of zirconia from monoclinic to cubic structure occurs, causing volume change and microcracks in the anode materials. Therefore, the optimum adding amount of Bi2O3 is 6[Formula: see text]wt.%, which can reduce the sintering temperature to 1250[Formula: see text]C. The ceramics with 6[Formula: see text]wt.% Bi2O3 have relatively high bending strength and low sintering temperature. This is of great significance for improving the performance of the anode and cutting the cost.

Preparation and Characterization of Al2O3 High Density Ceramic Materials

2013 ◽  
Vol 457-458 ◽  
pp. 266-269
Author(s):  
Chun Yan Jia ◽  
Dong Hong Li ◽  
Yong He Liu
Keyword(s):  
Sintering Temperature ◽  
Ceramic Materials ◽  
Volume Density ◽  
Raw Material ◽  
High Alumina ◽  
Molding Pressure ◽  
Alumina Powder ◽  
Alumina Ceramics ◽  
Shrinkage Ratio ◽  
Isostatic Compaction

With sub-micron alumina powder as raw material, high alumina ceramics were prepared through isostatic compaction. The volume density and shrinkage ratio were investigated. The influence of sintering temperature and molding pressure were studied on volume density and shrinkage ratio of ceramic. The results indicated that sintering characteristic of alumina ceramics could be improved at the appropriate sintering temperature and molding pressure and its sintering temperature could be decreased by using sub-micron alumina powder as raw material. 95 ceramics were prepared using sub-micron alumina as raw material, when the sintering temperature was 1550°C, molding pressure was 12 t, and ceramic volume density could be achieved 3.71g /cm3.

Mechanical Properties of SiC/FexSiy Composites

2011 ◽  
Vol 236-238 ◽  
pp. 1523-1527 ◽  
Author(s):  
Xiao Meng Zhang ◽  
Shu Feng Ye ◽  
Li Hua Xu ◽  
Peng Qian ◽  
Lian Qi Wei ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Raw Material ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Scanning Electron

The SiC/FexSiycomposites were synthesized by reaction sintering process with iron tailings as raw material and carbon as reductant. The room and high temperature flexural strengths and fracture toughness of composites were studied in this paper. Fracture surfaces were observed by means of a scanning electron microscope (SEM). The results showed that the room temperature flexural strength of SiC/FexSiycomposites changed along with the different contents of FexSiyand sintering temperature. The flexural strength of composites reaches the maximum at 900°C. The correlation between flexural strength and temperature is consistent with curveⅠ.The fracture toughness of composites is related to the content of FexSiy. The fracture behavior of composites is mainly transcrystalline in room temperature and intercrystalline in high temperature.

Effect of Copper Oxide on the Sintering of Alumina Ceramics

2008 ◽  
Vol 47-50 ◽  
pp. 801-804 ◽  
Author(s):  
Ramesh Singh ◽  
K.L. Aw ◽  
C.H. Ting ◽  
Chou Yong Tan ◽  
Iis Sopyan ◽  
...  
Keyword(s):  
Grain Size ◽  
Copper Oxide ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Alumina Ceramics ◽  
Maximum Hardness ◽  
Air Atmosphere ◽  
Al2o3 Phase ◽  
Α Al2o3 ◽  
Effect Of Copper

The effect of adding small amounts of copper oxide (CuO) on the sintering and mechanical properties of alumina ceramic was studied. Samples were prepared and fired in air atmosphere at temperatures ranging from 1400oC to 1600oC. Sintered samples were characterized to determine phase present, bulk density, hardness and grain size. The results indicated that all the doped samples could be sintered to high density > 3.85 Mgm−3 when compared to the undoped alumina. According to the XRD analysis, the α-Al2O3 phase was not disrupted by the dopant addition. Although the hardness of the CuO-doped material was higher when sintered below 1550°C, the maximum hardness of 21 GPa was measured for the undoped ceramics when sintered at 1600°C. The lower hardness of the doped samples could be attributed to the increased in grain size with increasing sintering temperature.

Effect of Phase Transformation and Fine Particle Dispersion on Densification of High Purity Nanocrystalline γ-Phase Dispersed α-Alumina

2007 ◽  
Vol 124-126 ◽  
pp. 831-834 ◽  
Author(s):  
Sang Woo Kim ◽  
Shin Young Kim
Keyword(s):  
Phase Transformation ◽  
High Purity ◽  
Fine Particle ◽  
Particle Dispersion ◽  
Nanoparticle Dispersion ◽  
Alumina Ceramics ◽  
Α Phase ◽  
Α Al2o3 ◽  
Rapid Transformation ◽  
Nanocrystalline Alumina

The effect of phase transformation and fine particle dispersion on densification behavior of high purity nanocrystalline alumina was investigated. The γ/α phase ratio of the mixture compacts were affected detrimentally by sinterability and phase transformation of α-phase alumina ceramics. The densification was significantly deteriorated with increasing γ-phase owing to faceted pores which are caused by the formation of a colony. The faceted pores were not existed in the α- Al2O3 ceramics with 10% γ-phase. Densification of the 10% γ-phase dispersed α-Al2O3 ceramics was significantly enhanced by rapid transformation of α-alumina. The grain growth was effectively inhibited by a small amount of nanoparticle dispersion for the alumina ceramics. As a result, dense nanostructured alumina can be achieved in the 10% γ-phase dispersed α-Al2O3 ceramics, even sintering at 1400oC for 3 hours.

Heat Preservation Time on the Properties of Red Mud Lightweight Insulation Brick

2014 ◽  
Vol 540 ◽  
pp. 225-228 ◽  
Author(s):  
Long Ma ◽  
Guo Zhong Li ◽  
Ji Rui Hu
Keyword(s):  
Electron Microscope ◽  
Fly Ash ◽  
Scanning Electron Microscope ◽  
Red Mud ◽  
Sintering Temperature ◽  
Raw Material ◽  
Sintering Process ◽  
Heat Preservation ◽  
Fluxing Agent ◽  
Scanning Electron

The red mud lightweight insulation brick was prepared by the sintering process as red mud, fly ash, bentonite as the main raw material, adding a certain amount of pore forming agent and fluxing agent. The sintering heat preservation time of red mud insulation brick on the properties was studied. The red mud lightweight insulation brick damage fracture microstructure was analyzed using scanning electron microscope (SEM) and the sintering mechanism was discussed preliminarily. The results show that with sintering temperature of 1100°C heating for 180 minutes, the performance of thermal insulation brick is better. When the heat preservation time extends to continue, the performances of sample remain stable basically.

Sintering Properties of Fused Silica/Nano-Zirconia Composite Ceramic

2013 ◽  
Vol 750-752 ◽  
pp. 81-84
Author(s):  
Yong Wu He ◽  
Jing Long Bu ◽  
Rui Sheng Wang ◽  
Dong Mei Zhao ◽  
Jun Xing Chen ◽  
...  
Keyword(s):  
Bulk Density ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Composite Ceramic ◽  
High Energy ◽  
Fused Silica ◽  
Raw Material ◽  
Composite Powders ◽  
Wet Chemical Synthesis ◽  
Sintering Properties

Zirconyl chloride was used as zirconium source and fused silica particles were used as main raw material. First of all, the composite powders were prepared by wet chemical synthesis using ammonia as the precipitator and polyethylene glycol as the dispersant. Then, fused silica nanozirconia composite ceramic containing nanometer particle zirconia with different contents (5%, 15%, 25% and 35%) were fabricated in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1 h. The bulk density and bending strength were measured, microstructure was observed by SEM. The result indicated bulk density and bending strength of composite ceramic increase and microstructure becomes denser with content of zirconia increasing. Bulk density of composite ceramic increases and bending strength which reaches maximum at 1350°C firstly increases then decreases with the increase of sintering temperature. Both high sintering temperature and nanozirconia possessing high energy interface can improve the composite ceramic sintering.

Effect of Fly Ash Pre-Sintering Temperature on Adiabatic Foam Fabricated by Sodium Silicate

2019 ◽  
Vol 295 ◽  
pp. 105-109
Author(s):  
Ye Li ◽  
Heng Ze Zhao ◽  
Xu Dong Cheng
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Pore Structure ◽  
Pore Size ◽  
Sodium Silicate ◽  
Sintering Temperature ◽  
Raw Material ◽  
Sintering Process ◽  
Spherical Pore

Adiabatic foam was fabricated successfully using sodium silicate as the raw material with pre-sintered fly ash as additive. Fly ash was pre-sintered at 500 to 900 oC and the effect of the pre-sintering temperature on the performance, including the thermal conductivity, density, compressive strength and microstructure, was researched. The results show that the pre-sintering process effectively reduces the density of the samples while the thermal conductivity and compressive strength are higher than those of the samples fabricated by the fly ash without being pre-sintered. Moreover, the samples exhibit tri-modal spherical pore structure with macropores and mesopores. The pore size remains unchanged until the pre-sintering temperature exceeds 700 oC, and then starts to increase.

Microstructure and Properties of 8YSZ with High Component BAS

2014 ◽  
Vol 541-542 ◽  
pp. 25-29
Author(s):  
Jin Qin ◽  
Gang Chen ◽  
Zhi Ming Du ◽  
Jia Hong Niu
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Sintering Aids ◽  
Sintering Time ◽  
Material Component ◽  
Time Density ◽  
Very High

The sintering temperature of 8YSZ (8mol% yttrium stabilized zirconia) is very high, usually above 1500°C. BAS (BaO-Al2O3-SiO2) microcrystalline glass can be used as sintering aids to reduce the sintering temperature of 8YSZ. In this research, large proportion (30-50wt%) BAS was added in 8YSZ to observe the influence of the sintering aids. The change rules of mechanical properties such as density test, bending strength and toughness in different material component and sintering process were researched. The results show that physical and mechanical performance improvement with the increase of sintering temperature and sintering time, density and bending strength decreases with the increase of BAS mass fraction. The optimal mechanical properties are obtained by sintering temperature 1300°C, sintering time 0.5h and 30wt% BAS.

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