Crystallization processes of cordierite glasses

Abstract

To prepare α‐cordierite glass ceramics, we demonstrate two types of phase diagrams of a composition 2MgO·2Al2O3·5SiO2 with time courses. One is the continuous‐cooling‐transformation (CCT) diagram; the other is the temperature‐time‐transformation (TTT) diagram. At ∼ 1273 K, μ‐cordierite is crystallized as the primary phase and then it transforms to α‐cordierite with a lath‐like martensite transformation. The volume expansion derived from this transformation results in a lot of cracks in crystallized glasses. Since the addition of MgF2 for the substitution of MgO (ca. 5%) suppresses the μ‐to α‐cordierite transformation but promotes the direct crystallization of α‐cordierite from glass, we can prepare α‐cordierite glass ceramics without cracks. In this paper, we point out the needs and usefulness of CCT and TTT diagrams for glass ceramics processing.

A SAXS/WAXS XAFS study of crystallisation in cordierite glass

“…Morinaga 41 reports devitrification experiments on cordierite glass using a single step heat treatment resulting in crystalline particles with dimensions up to 1000 A ˚. In the present work particle sizes do not exceed 300 A ˚, which highlights the role of the two-tier heat treatment employed.…”

The development of monodispersed alumino-chromate spinel nanoparticles in doped cordierite glass, studied by in situ X-ray small and wide angle scattering, and chromium X-ray spectroscopy

“…The double step heat treatment has important consequences for the final size of the nanocrystals. For example Morinaga [43] reports devitrification experiments on cordierite glass using a single step heat treatment in which the crystalline particles reaches dimensions up to 1000 Å . However, due to the use of the two step treatment presented in this work the particle sizes do not exceed 300 Å .…”

Containerless solidification of undercooled SrO–Al2O3 binary melts

“…2 Timetemperature-transformation (TTT) and continuous cooling transformation (CCT) diagrams are used to evaluate the tendency for glass formation or crystallization and to estimate R C . 1,[3][4][5][6][7][8][9][10][11][12][13] A TTT diagram is constructed by measuring the time of crystallization at a given temperature, while a CCT diagram is constructed by measuring the temperature and time of crystallization at a given cooling rate. TTT or CCT diagrams are typically obtained using thermal analysis methods such as differential thermal analysis and differential scanning calorimetry.…”