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In this paper, in-situ coagulation of 0.9Al2O3–0.1TiO2 suspension and microwave dielectric properties of 0.9Al2O3–0.1TiO2 ceramics prepared by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method were proposed. The 0.9Al2O3–0.1TiO2 suspension could be coagulated via controlled release of calcium ions from calcium iodate at an elevated temperature. The influence of tri-ammonium citrate (TAC) content, solid loading, and calcium iodate content on the rheological properties of the suspension was investigated. In addition, the influence of coagulation temperature on coagulation time and properties of green bodies was also studied. It was found that the stable 0.9Al2O3–0.1TiO2 suspension could be successfully prepared by adding 0.3 wt% TAC and adjusting pH value to 10–12 at room temperature. 0.9Al2O3–0.1TiO2 green bodies with uniform microstructures were coagulated by adding 8.0 g/L calcium iodate after treating at 70 ℃ for 1 h. 0.9Al2O3–0.1TiO2 ceramics, sintered at 1500 ℃ for 4 h and annealed at 1100 ℃ for 5 h, showed uniform microstructures with density of 3.62±0.02 g/cm3. The microwave dielectric properties of 0.9Al2O3–0.1TiO2 ceramics prepared by DCC-HVCI method were: εr= 11.26±0.06, Q×f = 11569± 629 GHz, τf= 0.93±0.60 ppm/℃. The DCC-HVCI method is a novel and promising route without binder removal process to prepare complex-shaped microwave dielectric ceramics with uniform microstructures and good microwave dielectric properties.


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Study of 0.9Al2O3–0.1TiO2 ceramics prepared by a novel DCC-HVCI method

Show Author's information Jia-Min WUHuan XIAOMeng-Yue LIUYing CHEN( )Yi-Xin MALi-Jin CHENG( )Yu-Sheng SHI
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

Abstract

In this paper, in-situ coagulation of 0.9Al2O3–0.1TiO2 suspension and microwave dielectric properties of 0.9Al2O3–0.1TiO2 ceramics prepared by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method were proposed. The 0.9Al2O3–0.1TiO2 suspension could be coagulated via controlled release of calcium ions from calcium iodate at an elevated temperature. The influence of tri-ammonium citrate (TAC) content, solid loading, and calcium iodate content on the rheological properties of the suspension was investigated. In addition, the influence of coagulation temperature on coagulation time and properties of green bodies was also studied. It was found that the stable 0.9Al2O3–0.1TiO2 suspension could be successfully prepared by adding 0.3 wt% TAC and adjusting pH value to 10–12 at room temperature. 0.9Al2O3–0.1TiO2 green bodies with uniform microstructures were coagulated by adding 8.0 g/L calcium iodate after treating at 70 ℃ for 1 h. 0.9Al2O3–0.1TiO2 ceramics, sintered at 1500 ℃ for 4 h and annealed at 1100 ℃ for 5 h, showed uniform microstructures with density of 3.62±0.02 g/cm3. The microwave dielectric properties of 0.9Al2O3–0.1TiO2 ceramics prepared by DCC-HVCI method were: εr= 11.26±0.06, Q×f = 11569± 629 GHz, τf= 0.93±0.60 ppm/℃. The DCC-HVCI method is a novel and promising route without binder removal process to prepare complex-shaped microwave dielectric ceramics with uniform microstructures and good microwave dielectric properties.

Keywords:

rheological properties, microwave dielectric properties, 0.9Al2O3–0.1TiO2, DCC-HVCI
Received: 31 December 2017 Revised: 03 March 2018 Accepted: 05 March 2018 Published: 28 March 2018 Issue date: June 2018
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Publication history

Received: 31 December 2017
Revised: 03 March 2018
Accepted: 05 March 2018
Published: 28 March 2018
Issue date: June 2018

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© The author(s) 2018

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