ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 64, (3) 365 - 370 (2020)


FOAM-GELCASTING PREPARATION OF Zr Si O₄ MODIFIED POROUS MULLITE CERAMICS
 
Liu Xueyin 1, Ge Shengtao 2, Zhang Haijun 2, Bi Yubao 2, Jia Quanli 3, Zhang Shaowei 4
 
1 College of Civil Engineering and Architecture, Quzhou University, Quzhou 324000, China
2 The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
3 School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China
4 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK

Keywords: Microstructure, Pore size distribution, Thermal conductivity, Mechanical property
 

ZrSiO₄ modified mullite-based porous ceramics were fabricated at 1400 °C by using a foam-gelcasting method from industrial grade powder materials. Except for mullite and ZrSiO₄ no other phases were identified in the fired samples added with ZrSiO₄, implying that at the firing temperature, ZrSiO₄ neither decomposed, nor reacted with mullite. In the microstructures of these samples, mullite/ZrSiO₄ grains were evenly distributed, and the overall pore sizes were reduced. The addition of ZrSiO₄ showed little effect on porosity and bulk density of fired samples, which were respectively around 77% and 0.7g.cm-3. However, it led to the enhanced mechanical strength, and more importantly, the reduced thermal conductivity, especially at high temperatures. When 8 wt% ZrSiO₄ was added, flexural and compressive strengths increased respectively to 3.63 and 7.35 MPa, whereas thermal conductivity at 200 and 1000 °C was reduced to 0.160 and 0.277 W.m-1.K-1, respectively, which was mainly attributed to the shading effect, decreased size of "large" spherical pores, and more centralized and homogenized pore size distribution.


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doi: 10.13168/cs.2020.0024
 
 
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