Densification kinetics of Alumina During Microwave Sintering

1992 ◽  
Vol 269 ◽  
Author(s):  
Jiping Cheng ◽  
Jinyu Qiu ◽  
Jian Zhou ◽  
Neng Ye
Keyword(s):  
High Temperature ◽  
Grain Growth ◽  
Microwave Field ◽  
Microwave Sintering ◽  
Alumina Ceramics ◽  
Kinetics Parameters ◽  
Fine Grained ◽  
Prolonged Time ◽  
Conventional Sintering ◽  
Kinetics Of

ABSTRACTSome kinetics parameters of alumina during microwave sintering were studied and compared with that during conventional sintering. The results demonstrated that the sintering rates for microwave processing were much greater than that for conventional processing, and the grain growth of alumina was rapid with prolonged time at high temperature in a microwave field. It was indicated that the microwave sintering at higher temperatures for a shorter time was favorable for preparing high density and fine-grained alumina ceramics.

scholarly journals Alumina ceramics obtained by chemical synthesis using conventional and microwave sintering

Cerâmica ◽  
2011 ◽  
Vol 57 (341) ◽  
pp. 45-49 ◽  
Author(s):  
D. Thomazini ◽  
M. V. Gelfuso ◽  
A. S. A. Chinelatto ◽  
A. L. Chinelatto ◽  
F. K. Sanson ◽  
...  
Keyword(s):  
Pechini Method ◽  
Microwave Sintering ◽  
Potential Candidate ◽  
Alumina Ceramics ◽  
Pure Alumina ◽  
Nanosized Powders ◽  
Fine Grained ◽  
Conventional Furnace ◽  
Microwave Furnace ◽  
Conventional Sintering

It is well known that the heating mechanism and powder precursor define the microstructural characteristics of ceramics. Especially abnormal grain growth of pure alumina ceramics developed during conventional sintering method suggests that this material is a potential candidate to be treated in microwave sintering process. Alumina ceramics produced with commercial (A1K) and chemically synthesized powders were sintered in conventional and microwave furnaces. Two methods were employed to prepare the chemically synthesized nanosized powders: Pechini method and emulsification with oleic acid. The microwave sintered samples were characterized by apparent density and scanning electron microscopy and compared with the samples sintered in a conventional furnace. Alumina ceramics sintered in the microwave furnace had fine grained microstructure, not related with the starting powders. This characteristic was achieved in a sintering time shorter than those produced in the conventional furnace. However, satisfactory densification was observed only to A1K ceramics (3.95 g/cm³) sintered during one hour in microwave furnace.

Nanostructure Evolution of ZnO in Ultra-fast Microwave Sintering

2011 ◽  
Vol 691 ◽  
pp. 65-71 ◽  
Author(s):  
Rodolfo F. K. Gunnewiek ◽  
Ruth Herta Goldsmith Aliaga Kiminami
Keyword(s):  
Grain Size ◽  
Zinc Oxide ◽  
Grain Growth ◽  
Microwave Sintering ◽  
High Heating Rate ◽  
Heating Rates ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Holding Temperature

Grain growth is inevitable in the sintering of pure nanopowder zinc oxide. Sintering depend on diffusion kinetics, thus this growth could be controlled by ultra-fast sintering techniques, as microwave sintering. The purpose of this work was to investigate the nanostructural evolution of zinc oxide nanopowder compacts (average grain size of 80 nm) subjected to ultra-rapid microwave sintering at a constant holding temperature of 900°C, applying different heating rates and temperature holding times. Fine dense microstructures were obtained, with controlled grain growth (grain size from 200 to 450nm at high heating rate) when compared to those obtained by conventional sintering (grain size around 1.13µm), which leads to excessively large average final grain sizes.

β Grain Growth Kinetics of Hot-Rolled TB-13 Alloy

2011 ◽  
Vol 689 ◽  
pp. 472-478 ◽  
Author(s):  
Yue Fei ◽  
Bin Tang ◽  
Hui Chang ◽  
Zhi Shou Zhu ◽  
Zhong Bo Zhou ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Kinetic Equations ◽  
Type Equation ◽  
Growth Exponent ◽  
Fine Grained ◽  
Solution Treated ◽  
Grain Growth Kinetics ◽  
Hot Rolled ◽  
Kinetics Of

A study on the kinetics of β grain growth of a fine-grained, hot-rolled TB-13 alloy was carried out by isochronal and isothermal solution treatments. The grain size of the as-rolled and as-solution-treated samples was determined by metallographic observation using the linear intercept method. The kinetic equations and the Arrhenius-type equation were applied to calculate the β grain growth exponent and the activation energy for β grain growth at special temperatures. The results showed that the β grain growth rate decreased with elongating solution treated time, but increased with increasing solution treated temperature. The β grain growth exponents (n) were 0.394, 0.403 and 0.406 during the solution treated temperatures at 1103K, 1153K and 1203K, respectively. The values of n increased with increasing solution treated temperature and the determined activation energy (Qm) for β grain growth after holding for 0.5h at 1103K-1203K was around 156KJ/mol.

scholarly journals Can Ultra-fast High Temperature Sintering (UHS) Boost Transparency of Alumina?

2021 ◽  
Author(s):  
Milad Kermani ◽  
Danyang Zhu ◽  
Jiang Li ◽  
Jinghua Wu ◽  
Yong Lin ◽  
...  
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Green Density ◽  
Alumina Ceramics ◽  
Fine Grained ◽  
Reducing Atmosphere ◽  
Transparent Alumina ◽  
Rapid Sintering ◽  
First Time

Abstract Established routes for consolidation of transparent alumina ceramics by pressure-less sintering requires several hours of dwelling in a reducing atmosphere at a temperature exceeding 1600 ℃. Here, for the first time, we report on low temperature and ultrafast consolidation of translucent alumina ceramics. Transparency was promoted by the synergistic of high initial green density (62.7 %) and rapid sintering using Ultra-fast High Temperature Sintering (UHS) technique. The proposed approach, using a heating rate of 430 ℃/min and dwelling time of 15 minutes, resulted in ultra-fine-grained translucent alumina ceramics at 1359 ± 57 ℃ with a grain size of 0.39 µm, and an in-line transmittance of 28.7 % at a wavelength of 700 nm. For comparison, conventionally fired counterparts were opaque due to their incomplete densification, pore coalescence.

scholarly journals Kinetics of recrystallization and grain growth in an ultra-fine grained CoCrFeNiMn-type high-entropy alloy

2019 ◽  
Vol 1270 ◽  
pp. 012053
Author(s):  
M V Klimova ◽  
D G Shaysultanov ◽  
R S Chernichenko ◽  
V N Sanin ◽  
S V Zherebtsov ◽  
...  
Keyword(s):  
Grain Growth ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Fine Grained ◽  
Kinetics Of

Compaction and grain growth in alumina ceramics under microwave sintering

1997 ◽  
Vol 36 (7-8) ◽  
pp. 359-363 ◽  
Author(s):  
V. V. Panichkina ◽  
E. A. Shevchenko ◽  
Yu. V. Bykov ◽  
A. G. Eremeev
Keyword(s):  
Grain Growth ◽  
Microwave Sintering ◽  
Alumina Ceramics

scholarly journals Ultra-fast High Temperature Sintering (UHS) of ultra-fine-grained translucent alumina ceramics

Open Ceramics ◽  
2021 ◽  
pp. 100202
Author(s):  
Milad Kermani ◽  
Danyang Zhu ◽  
Jiang Li ◽  
Jinghua Wu ◽  
Yong Lin ◽  
...  
Keyword(s):  
High Temperature ◽  
Alumina Ceramics ◽  
Fine Grained

Microwave-Material Interaction in Oxide Ceramics with Different Additives

2006 ◽  
Vol 45 ◽  
pp. 845-850
Author(s):  
Monika Willert-Porada ◽  
Zahra Negahdari ◽  
T. Gerdes ◽  
Achim Müller ◽  
M. Paneerselvam
Keyword(s):  
Grain Growth ◽  
Microwave Field ◽  
Volume Ratio ◽  
Conventional Heating ◽  
Small Samples ◽  
Oxide Ceramics ◽  
Volumetric Heating ◽  
Conventional Sintering ◽  
Grain Boundary Pinning ◽  
Material Interaction

A systematic study upon microwave (2.45 GHz frequency) and conventional heating (resistance heating furnace) was undertaken on porosity, grain growth and densification of commercial grade Al2O3-ceramics doped with MgO (aliovalent doping), with ZrO2 (grain boundary pinning) and with additives promoting elongated grain growth (LaAlO 3 and La2O3, AlPO4). Processes accompanied by a strong non-equilibrium situation, e.g., dissolution, segregation, vacancy formation, are influenced by the presence of the microwave field during heat treatment, visible on microstructure differences of microwave as compared to conventionally sintered samples. Regular grain growth is almost not affected by the microwave field, but the on-set of exaggerated grain growth and pore coalescence is delayed and occurs at higher density as compared to conventional sintering. Such microstructure differences seem to be more pronounced if the surface to volume ratio of the samples is low, therefore volumetric heating has a larger contribution to transport phenomena as compared to small samples.

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