Mechanical Properties of Kaolin during Heating

Abstract:

Flexural strength (MOR) and Young’s modulus (YM) of Sedlec kaolin were measured using the three point-bending method and modulated force thermomechanical analysis (mf-TMA). Thermal analyses DTA, thermogravimetry and thermodilatometry (TDA). An escape of the physically bound water (20 – 250 °C) strengthens the sample and YM and MOR increase their values significantly. MOR and YM lower their values as dehydroxylation starts at 400 °C. Both quantities, MOR and YM, pass through minimum in the dehydroxylation region (400 – 650 °C). Their next increase is probably caused by the van der Waals forces acting between metakaolinite crystals and by the starting of the solid-state sintering. YM steeply increases above 950 °C as a consequence of the solid-state sintering. A Weibull’s modulus passes through the sharp maximum at the interval 300 – 400 °C.

• Periodical: Key Engineering Materials (Volume 527)
• Pages: 14-19
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.527.14
• Online since: November 2012
• Authors: Igor Štubňa, Peter Šín, Anton Trník, Renno Veinthal
• Keywords: Dehydration, Dehydroxylation, Firing, Flexural Strength, Kaolin, Young's Modulus

References

[1] C.Y. Chen, G.S. Lan, W.H. Tuan, Microstructural evolution of mullite during the sintering of kaolin powder compacts, Ceramics International 26 (2000) 715-720.

DOI: 10.1016/s0272-8842(00)00009-2

[2] F. Freund, Kaolinite-metakaolinite, a model of a solid with extremely high lattice defect concentration, Ber. Deutsche Keram. Ges. 44, N4 (1967) 5-13.

[3] F.H. Norton, Fine ceramics – technology and applications, McGraw-Hill Book Co., New York, 1970.

[4] V. Hanykýř, J. Kutzendorfer, Technology of ceramics, Silis Praha a Vega, Hradec Králové, 2000 (in Czech).

[5] G. Varga, Structure of kaolinite and metakaolinite, Épitoanyag – Building Materials 58, N1 (2007) 6-9.

[6] A. Gualtieri, M. Bellotto, G. Artioli, S.M. Clark, Kinetic study of the kaolinite-mullite reaction sequence, Part II: Mullite formation, Physics and Chemistry of Minerals 22, N4 (1995) 215-222.

DOI: 10.1007/bf00202254

[7] B. Sonuparlak, M. Sarikaya, I. Aksay, Spinel phase formation during the 980 °C exothermic reaction in the kaolinite-mullite reaction series, J. Amer. Ceram. Soc. 70 (1987) 837-842.

DOI: 10.1111/j.1151-2916.1987.tb05637.x

[8] H. Meshbah, M.A. Wilson, M.A. Carter, The role of the kaolinite-mullite sequence in moisture mass gain in fired kaolinite, Advances in Science and Technology 68 (2010) 38-43.

DOI: 10.4028/www.scientific.net/ast.68.38

[9] I. Štubňa, T. Kozík, Permeability of the electroceramics to gas and its dependence on the firing temperature, Ceramics International 23 (1997) 247-249.

DOI: 10.1016/s0272-8842(96)00034-x

[10] I. Štubňa, A. Trník, P. Šín, R. Sokolář, I. Medveď, Relationship between mechanical strength and Young´s modulus in traditional ceramics, Materiali in tehnologije 45 (2011) 375-378.

[11] I. Štubňa, A. Trník, L. Vozár, Thermomechanical and thermodilatometric analysis of green alumina porcelain, Ceramics International 35 (2009) 1181-1185.

DOI: 10.1016/j.ceramint.2008.05.004

[12] I. Štubňa, A. Trník, F. Chmelík, L. Vozár, Mechanical properties of kaolin-base ceramics during firing, in: Costas Sikalidis (Eds.), Advances in Ceramics – characterization, raw materials, processing, properties, degradation and healing, InTech, Rijeka, 2011, pp.229-244.

DOI: 10.5772/19199

[13] I. Štubňa, A. Trník, L. Vozár, Determination of Young's modulus of ceramics from flexural vibration at elevated temperatures, Acta Acustica + Acustica 97 (2011) 1-7.

DOI: 10.3813/aaa.918380

[14] R. Riedlmajer, I. Štubňa, G. Varga, Thermoelectric and thermodilatometric analysis of English kaolins, Silika 16 (2006) 119-121 (in Slovakian).