素材
Cordierite
Japanese: コーディエライト
A refractory material (Mg₂Al₄Si₅O₁₈) with an extremely low coefficient of thermal expansion. It is highly resistant to repeated heating and rapid cooling, making it an excellent choice for kiln shelves, supports, and large slump molds.
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Cordierite (Mg₂Al₄Si₅O₁₈) is a magnesium -alumin silicate refractory mineral and ceramic; its most distinctive feature is its extremely low coefficient of thermal expansion (linear expansion coefficient α ≈ 1–2 × 10⁻⁶/K, approximately 1/5 to 1/9 that of glass at COE90) (§16.1). Due to its low thermal expansion coefficient, it is resistant to thermal shock cracking caused by repeated rapid heating and cooling, making it an excellent refractory material for kiln shelves, supports, and large slump molds.
The primary applications of cordierite in kiln work are shelf plates and kiln posts, where it is valued for its durability in withstanding repeated firings. Although it is more expensive than typical shelf materials (such as mullite-based ceramics), its long service life and thermal shock resistance enable high-quality, long-term operation. Because cordierite shelves have a significant difference in thermal expansion coefficient compared to glass, they provide a stable support surface that prevents glass from slipping during firing. They are also used in large slump molds (60 cm or wider), reducing the risk of mold cracking during slump forming. They are used after applying a release agent (such as Bullseye Shelf Primer).
Related Concepts
Understand the thermal properties and appropriate uses of mold materials and shelf materials, including ceramic fiber, Selvane, refractory plaster, and thermal diffusivity (κ).
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.