High-temperature Young's moduli and dilatation behavior of silica refractories
| Název česky | Vysokoteplotní Youngův modul a dilatace dinasových žáromateriálů |
|---|---|
| Autoři | |
| Rok publikování | 2016 |
| Druh | Článek v odborném periodiku |
| Časopis / Zdroj | JOURNAL OF THE EUROPEAN CERAMIC SOCIETY |
| Fakulta / Pracoviště MU | |
| Citace | |
| Doi | http://dx.doi.org/10.1016/j.jeurceramsoc.2015.09.020 |
| Obor | Keramika, žáruvzdorné materiály a skla |
| Klíčová slova | Silica refractories; Young's modulus; Elastic modulus; Dilatation; Dilatometry; Impulse excitation; Cristobalite; Tridymite |
| Popis | 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 degrees C and by dilatometry up to 1300 degrees C. During heating, Young's moduli start to decrease from their room temperature values (9-12 GPa) to about 5-7 GPa at 200 degrees C, followed by a very steep increase at around 230 degrees 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 degrees C and a final increase to the intial 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 degrees 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 degrees 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. (C) 2015 Elsevier Ltd. All rights reserved. |
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