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Fractal theory and regression analysis were employed for the first time to investigate the effect of pore size and pore distribution on high-temperature mechanical properties of porous alumina ceramics (PAC). In the present work, PAC with the comparable porosity, different pore sizes and pore distributions were prepared using carbon black as the pore-forming agent. Particular emphasis in this study was placed on the establishment of correlation between the thermal shock resistance and pore properties. The relationship between fractal dimension ( Df) and thermal shock resistance parameter ( Rst) in specimens presented the negative power function, indicating that low Df could benefit the improvement of thermal shock resistance in specimens. The results showed that the increase of pore size and pore sphericity leads to a reduced Df, the enhanced hot modulus of rupture (HMOR) and Rst. The decrease of proportion of micro-pores below 2 µm, the increase of mean pore size and pore sphericity could result in the decrease of Df, and then improve Rst and HMOR of specimens. Based on the correlation between Rst and pore characteristics, PAC with improved thermal shock resistance could be achieved when their pore structure meets the above features.


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Optimal design on the high-temperature mechanical properties of porous alumina ceramics based on fractal dimension analysis

Show Author's information Jingjing LIUa,bWenlong HUOaXiaoyan ZHANGaBo RENa( )Yuanbing LIbZaijuan ZHANGaJinlong YANGa( )
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China

Abstract

Fractal theory and regression analysis were employed for the first time to investigate the effect of pore size and pore distribution on high-temperature mechanical properties of porous alumina ceramics (PAC). In the present work, PAC with the comparable porosity, different pore sizes and pore distributions were prepared using carbon black as the pore-forming agent. Particular emphasis in this study was placed on the establishment of correlation between the thermal shock resistance and pore properties. The relationship between fractal dimension ( Df) and thermal shock resistance parameter ( Rst) in specimens presented the negative power function, indicating that low Df could benefit the improvement of thermal shock resistance in specimens. The results showed that the increase of pore size and pore sphericity leads to a reduced Df, the enhanced hot modulus of rupture (HMOR) and Rst. The decrease of proportion of micro-pores below 2 µm, the increase of mean pore size and pore sphericity could result in the decrease of Df, and then improve Rst and HMOR of specimens. Based on the correlation between Rst and pore characteristics, PAC with improved thermal shock resistance could be achieved when their pore structure meets the above features.

Keywords:

porous alumina ceramics (PAC), pore size, thermal shock resistance, high-temperature mechanical properties, fractal dimension
Received: 13 November 2017 Revised: 20 January 2018 Accepted: 21 January 2018 Published: 02 March 2018 Issue date: June 2018
References(31)
[1]
E Gregorová, W Pabst, Z Živcová, et al. Porous alumina ceramics prepared with wheat flour. J Eur Ceram Soc 2010, 30: 2871–2880.
[2]
T Shimizu, K Matsuura, H Furue, et al. Thermal conductivity of high porosity alumina refractory bricks made by a slurry gelation and foaming method. J Eur Ceram Soc 2013, 33: 3429–3435.
[3]
M Han, X Yin, L Cheng, et al. Effect of core–shell microspheres as pore-forming agent on the properties of porous alumina ceramics. Mater Design 2017, 113: 384–390.
[4]
DS Li, ZQ Lu, JZ Zhao. Development of alumina bubble brick with good shock resistance. Naihuo Cailiao 1997, 31: 284–285. (in Chinese)
[5]
W Zang, F Guo, J Liu, et al. Lightweight alumina based fibrous ceramics with different high temperature binder. Ceram Int 2016, 42: 10310–10316.
[6]
I Zake-Tiluga, V Svinka, R Svinka, et al. Thermal shock resistance of porous Al2O3–mullite ceramics. Ceram Int 2015, 41: 11504–11509.
[7]
AK Singh, R Sarkar. Development of spinel sol bonded high pure alumina castable composition. Ceram Int 2016, 42: 17410–17419.
[8]
A Shyam, G Bruno, TR Watkins, et al. The effect of porosity and microcracking on the thermosmechanical properties of cordierite. J Eur Ceram Soc 2015, 35: 4557–4566.
[9]
X Jin, L Dong, H Xu, et al. Effects of porosity and pore size on mechanical and thermal properties as well as thermal shock fracture resistance of porous ZrB2–SiC ceramics. Ceram Int 2016, 42: 9051–9057.
[10]
JH She, Y Beppu, JF Yang, et al. Effects of porosity on thermal shock resistance of silicon nitride ceramics. In Proceedings of the 26th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: B: Ceramic Engineering and Science Proceedings, 2002, 23: 247–252.
[11]
DPH Hasselman, G Ziegler. On the effect of crack growth on the scatter of strength of brittle materials. Ceram Int 1985, 11: 134.
[12]
Y Li, X Li, B Zhu, et al. The relationship between the pore size distribution and the thermo-mechanical properties of high alumina refractory castables. Int J Mater Res 2016, 107: 263–268.
[13]
WJ Lee, YJ Cho, HS Lee, et al. Effect of pore morphology on elastic, heat conduction and thermal shock fracture behaviors of porous ceramics. Procedia Engineering 2011, 10: 2459–2463.
[14]
X Jin, L Dong, H Xu, et al. Effects of porosity and pore size on mechanical and thermal properties as well as thermal shock fracture resistance of porous ZrB2–SiC ceramics. Ceram Int 2016, 42: 9051–9057.
[15]
K Foroutan-Pour, P Dutilleul, DL Smith. Advances in the implementation of the box-counting method of fractal dimension estimation. Appl Math Comput 1999, 105: 195–210.
[16]
PL Barbera, R Rosso. On the fractal dimension of stream networks. Water Resour Res 1989, 25: 735–741.
[17]
G-P Wei, B-Q Zhu, X-C Li, et al. Correlativity between pore structure parameters and thermal conductivity of cenosphere insulating refractory. Journal of Functional Materials 2012, 43: 3432–3436.
[18]
S Wang, C Deng, X Zhang, et al. Pore volume fractal dimension of magnesium olivine heat insulation materials. Journal of the Chinese Ceramic Society 2015, 43: 351–357.
[19]
G Pia, U Sanna. An intermingled fractal units model and method to predict permeability in porous rock. Int J Eng Sci 2014, 75: 31–39.
[20]
G Pia, L Casnedi, U Sanna. Porous ceramic materials by pore-forming agent method: An intermingled fractal units analysis and procedure to predict thermal conductivity. Ceram Int 2015, 41: 6350–6357.
[21]
B Zhu, G Wei; X Li. Characteristization of pore size distribution for porous insulating refractories by image analysis technique. Journal of the Chinese Ceramic Society 2012, 40: 1369–1375.
[22]
S Jin, J Zhang, S Han. Fractal analysis of relation between strength and pore structure of hardened mortar. Constr Build Mater 2017, 135: 1–7.
[23]
J Liu, Y Li, Y Li, et al. Effects of pore structure on thermal conductivity and strength of alumina porous ceramics using carbon black as pore-forming agent. Ceram Int 2016, 42: 8221–8228.
[24]
L Fu, H Gu, A Huang, et al. Possible improvements of alumina–magnesia castable by lightweight microporous aggregates. Ceram Int 2015, 41: 1263–1270.
[25]
D Veljović, R Jančić-Hajneman, I Balać, et al. The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics. Ceram Int 2011, 37: 471–479.
[26]
X Zhong, H Zhao. High-temperature properties of refractory composites. Am Ceram Soc Bull 1999, 78: 98–101.
[27]
DPH Hasselman. Unified theory of thermal shock fracture initiation and crack propagation in brittle ceramics. J Am Ceram Soc 1969, 52: 600–604.
[28]
DPH Hasselman. Elastic energy at fracture and surface energy as design criteria for thermal shock. J Am Ceram Soc 1963, 46: 535–540.
[29]
WD Kingery. Factors affecting thermal stress resistance of ceramic materials. J Am Ceram Soc 1955, 38: 3–15.
[30]
JR Thomas Jr., JP Singh, DPH Hasselman. Analysis of thermal stress resistance of partially absorbing ceramic plate subjected to asymmetric radiation, I: Convective cooling at rear surface. J Am Ceram Soc 1981, 64: 163–169.
[31]
A Kayama, M Tanaka, R Kato. Application of slit island method to the evaluation of the fractal dimension of the grain-boundary fracture in high-temperature creep. J Mater Sci Lett 2000, 19: 565–567.
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Publication history

Received: 13 November 2017
Revised: 20 January 2018
Accepted: 21 January 2018
Published: 02 March 2018
Issue date: June 2018

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© The author(s) 2018

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