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

作者：Pabst Willi^*; Gregorova Eva; Klouzek Jaroslav; Klouzkova Alexandra; Zemenova Petra; Kohoutkova Martina; Sedlarova Ivona; Lang Karel; Kotoucek Miroslav; Nevrivova Lenka; Vsiansky Dalibor

来源：Journal of the European Ceramic Society, 2016, 36(1): 209-220.

DOI：10.1016/j.jeurceramsoc.2015.09.020

• Silica refractories
• Young's modulus
• Elastic modulus
• Dilatation
• Dilatometry
• Impulse excitation
• Cristobalite
• Tridymite

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.

• 出版日期2016-1