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Journal of Advanced Ceramics  2016, Vol. 5 Issue (4): 291-297    doi: 10.1007/s40145-016-0202-4
Research Article     
Preparation of large size ZTA ceramics with eccentric circle shape by microwave sintering
Yongqiang CHENab,Bingbing FANbc*,Gang SHAOb,Rui ZHANGab*
aZhengzhou University of Aeronautics, Henan 450015, China
bSchool of Materials Science and Engineering, Zhengzhou University, Henan 450001, China
cSinosteel Luoyang Institute of Refractories Research Co., Ltd., Henan 471039, China
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Abstract  

Ultra-large zirconia toughened alumina (ZTA, mass ratio of Al2O3 and ZrO2 is 78:22) ceramics with eccentric circle shape were successfully sintered by microwave sintering with a multi-mode cavity at 2.45 GHz. The dimension of ZTA ceramics (green body) is 165 mm (outer diameter) × 25 mm (thickness). The optimized sintering temperature of microwave sintering is about 1500 ℃ for 30 min, and the total sintering time is about 4 h which is much shorter than that of conventional sintering. An auxiliary-heating insulation device was designed based on the principle of local caloric compensation to guarantee the intact sintered samples. With the increasing of sintering temperature, more and more microwave energy is absorbed within the entire sample, volumetric densification performs, and phases shift from m-ZrO2 phase to t-ZrO2 phase and cause Al2O3 grain growth.



Key wordslarge size ZTA ceramics      eccentric circle shape      microwave sintering      local caloric compensation     
Received: 22 April 2016      Published: 20 December 2016
Corresponding Authors: Bingbing FAN,Rui ZHANG   
Cite this article:

Yongqiang CHEN,Bingbing FAN,Gang SHAO,Rui ZHANG. Preparation of large size ZTA ceramics with eccentric circle shape by microwave sintering. Journal of Advanced Ceramics, 2016, 5(4): 291-297.

URL:

http://jac.tsinghuajournals.com/10.1007/s40145-016-0202-4     OR     http://jac.tsinghuajournals.com/Y2016/V5/I4/291

Fig. 1 Industrial application of ZTA ceramics as seal valves.
Fig. 2 Dimensions of ZTA ceramics: (a) green body, (b) sintered sample.
Fig. 3 Sketch of auxiliary-heating insulation device: (a) original structure, (b) optimized structure. 1—mullite light brick, 2—silicon carbide rod, 3—sample.
Fig. 4 (a) Input power, reflected power, and sintering temperature vs. sintering time for cracked sample; (b) cracked ZTA ceramics.
Fig. 5 (a) Input power, reflected power, and sintering temperature vs. sintering time for intact sample; (b) intact ZTA ceramics.
Fig. 6 Bending strength and porosity of ZTA ceramics.
Fig. 7 Vickers hardness and bulk density of ZTA ceramics.
Fig. 8 Microstructure of ZTA ceramics at different sintering temperatures: (a) 1350 ℃, (b) 1400 ℃, (c) 1450 ℃, (d) 1500 ℃, (e) 1550 ℃, (f) 1450 ℃.
Fig. 9 XRD patterns of ZTA ceramics.ADDIN
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