Thermal Property of Bizen-yaki Clay

Abstract

Identification of clay minerals and a study of their thermal properties were conducted for Bizen-yaki clay by means of thermal analysis, X-ray diffraction and electron microscopy. Main components of clay minerals in Bizen-yaki clay consisted of metahalloysite, mica clay minerals and montmorillonite. Quartz and feldspar were accompanied as non-clay minerals. The first shrinkage due to the dehydroxylation of metahalloysite occurred between 500° and 600°C on the dilatometric curve of a hydraulically elutriated clay, while the expansion due to a-0 transition of quartz appeared on the curve of Bizen-yaki clay. The second shrinkage due to the formation of r-Al208 from metahalloysite appeared between 850° and 1000°C and the third one caused by the collapse of mica clay minerals and the subsequent formation of mullite appeared between 1000° and 1200°C. The last shrinkage due to the melting of Bizenyaki clay started at the temperature higher than 1400°C.