High-temperature Young’s moduli and dilatation behavior of silica refractories

0450816 - ÚSMH 2017 RIV GB eng J - Článek v odborném periodiku
Pabst, W. - Gregorová, E. - Kloužek, Jaroslav - Kloužková, A. - Zemenová, P. - Kohoutková, M. - Sedlářová, I. - Lang, K. - Kotouček, M. - Nevřivová, L. - Všianský, D.
High-temperature Young’s moduli and dilatation behavior of silica refractories.
Journal of the European Ceramic Society. Roč. 36, č. 1 (2016), s. 209-220. ISSN 0955-2219. E-ISSN 1873-619X
Institucionální podpora: RVO:67985891
Klíčová slova: silica refractories * Young’s modulus * elastic modulus * dilatation * dilatometry
Kód oboru RIV: JH - Keramika, žáruvzdorné materiály a skla
Impakt faktor: 3.454, rok: 2016

Silica refractories with cristobalite–tridymite ratios between 0.83–0.86 and 1.43–1.47 and porosities of 13–17% are characterized by impulse excitation up to 1200°C and by dilatometry up to 1300°C. During heating, Young’s moduli start to decrease from their room temperature values (9–12 GPa) to about 5–7 GPa at 200°C, followed by a very steep increase at around 230°C to values higher than the room temperature values and a nonlinear increase to their final high-temperature values. During cooling, Young’s moduli increase even further, exhibit a maximum and a nonlinear decrease that does not follow the heating curve, a very steep decrease at around 200°C and a final increase to the initial room temperature values, so that a closed loop results during thermal cycling. Dilatometric measurements confirm that the strong increase of the Young’s modulus at around 230°C (during heating) can be attributed to the phase transition between low- and high-temperature cristobalite, while the more gentle—but still very significant—changes in Young’s moduli below 200°C are due to the more diffuse transitions between tridymite subpolymorphs. Microcracks are identified as the primary cause of the low Young’s moduli and their increase with temperature.
Trvalý link: http://hdl.handle.net/11104/0258808