Green samples (50 w/% of kaolin, 25 w/% of quartz and 25 w/% of feldspar) are prefired up to 400-1200 °C and analyzed during their second firing. Thermogravimetry, thermodilatometry and dynamic thermomechanical analyses are performed in a range from room temperature to 1100 °C. In the samples prefired at temperatures of up to 400 °C and 500 °C, the release of physically bound water has a significant influence on Young's modulus, increasing its values by ≈25 % and 6.5 %, respectively, between room temperature and 200 °C. In the samples prefired at temperatures above 500 °C, the α → β transition of quartz governs Young's modulus in a temperature interval of 500-700 °C. Young's modulus increases by 29-40 % in the samples prefired at 600-1200 °C due to the closing of the cracks located around quartz grains. The presence of a glassy phase is not necessary for the steep increase of Young's modulus around the α → β transition of quartz. At high temperatures, an increase in Young's modulus is caused by solid-phase sintering (above 800 °C), formation of Al-Si spinel (≈950-980 °C) and crystallization of mullite (above 1050 °C).
CITATION STYLE
Trník, A., Štubòa, I., Ondruška, J., Šín, P., & Csáki, Š. (2019). Young’s modulus of prefired quartz porcelain in a temperature range of 20-1200 °C. Materiali in Tehnologije, 53(4), 535–541. https://doi.org/10.17222/mit.2018.252
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