Evolution of Thermal Microcracking in Refractory ZrO2-SiO2 after Application of External Loads at High Temperatures

Materials

Giovanni Bruno¹  René Laquai¹  BerndRandolf Müller¹  Thierry Chotard²  Fanny Gouraud²  Marc Huger²  Guy Antou² 

[1] Bundesanstalt für Materialforschung und-prüfung (BAM), Unter den Eichen 87, D-12200 Berlin, Germany;Centre Européen de la Céramique, University of Limoges, 12 Rue Atlantis, 87068 Limoges, France;

关键词: electro-fused zirconia;    microcracking;    synchrotron x-ray refraction radiography (SXRR);    thermal expansion;   

DOI  :  10.3390/ma12071017

来源: DOAJ

【 摘 要 】

Zirconia-based cast refractories are widely used for glass furnace applications. Since they have to withstand harsh chemical as well as thermo-mechanical environments, internal stresses and microcracking are often present in such materials under operating conditions (sometimes in excess of 1700 °C). We studied the evolution of thermal (CTE) and mechanical (Young’s modulus) properties as a function of temperature in a fused-cast refractory containing 94 wt.% of monoclinic ZrO₂ and 6 wt.% of a silicate glassy phase. With the aid of X-ray refraction techniques (yielding the internal specific surface in materials), we also monitored the evolution of microcracking as a function of thermal cycles (crossing the martensitic phase transformation around 1000 °C) under externally applied stress. We found that external compressive stress leads to a strong decrease of the internal surface per unit volume, but a tensile load has a similar (though not so strong) effect. In agreement with existing literature on β-eucryptite microcracked ceramics, we could explain these phenomena by microcrack closure in the load direction in the compression case, and by microcrack propagation (rather than microcrack nucleation) under tensile conditions.

【 授权许可】

Unknown