High-temperature resistant glass-ceramics based on Sr-anorthite and tialite phases

We have identified a convenient strategy for the control of the thermal growth of monoclinic Sr-anorthite and tialite phases in Sr-Ti-Al-silicates. The proposed method gives rise to a novel glassceramic material with thermal, mechanical, and dielectric properties potentially interesting in applications which require high temperature resistant radiotransparent materials. Crucially, we have found that the selective growth of Al 2TiO 5 and monoclinic SrAl 2Si 2O 8 is enabled by keeping the SrO/Al 2O 3 ratio lower than unity. This strategy permits to prevent the crystallisation of detrimental rutile and hexagonal Sr-anorthite. Interestingly, the stable properties of monoclinic Sr-anorthite, never used in conjunction with tialite, give rise to a glassceramic system with good mechanical resistance (micro-hardness 9.6 GPa, modulus of rupture 100 MPa) and with relatively stable values of thermal expansion (49×10 -7°C- 1 from 20 to 1250 °C), thermal diffusivity (0.45×10 -6m2s- 1), thermal conductivity (1.0 W °C -1 m -1), and dielectric constant (8.2) up to 1200 °C. © 2012 Elsevier Ltd and Techna Group S.r.l.