Artificial Flexible Stone

Abstract

Itacolumite (flexible sandstone, Konnyaku-ishi), which exists naturally, is sedimentary or metamorphic quartzite. It has three-dimensional interlock crack among the grain boundaries similar to the jigsaw puzzle, and moves freely in a limited arc. We consider that flexibility of itacolumite is applied to stress relaxation mechanism of ceramics. In order to make microcrack similar to itacolumite, we used two kinds of ceramics with different thermal expansion coefficient. Low-thermal-expansion potassium zirconium phosphate (KZr₂(PO₄)₃) and high-thermal-expansion potassium aluminum silicate (KAlSi₂O₆) were mixed at various rate, formed and sintered. Composites had the crack among the grain boundaries and showed stress-strain diagram similar to itacolumite.