ScienceAsia 33 (2007): 125-130 |doi: 10.2306/scienceasia1513-1874.2007.33.125

Characterisation of Vieng Kalong Clays and Relation between Physical Properties and Bloating

Darunee Wattanasiriwech¹,Chiewchan Sangtong and Suthee Wattanasiriwech

 
ABSTRACT: This research aimed to study physical properties of two ball clays received from Ban Tung (TC) and Ban Rong (RC), Tambol Vieng Kalong, Chiang Rai, Thailand, and also to identify the key factors that affect the quality of the ceramic wares made from these clays. X-ray diffraction (XRD) and X-ray fluorescence (XRF) results revealed that RC clay contained higher free quartz content, while TC clay contained higher flux minerals. TC clay exhibited higher drying and firing shrinkage but lower water absorption after firing at 1250 °C. After firing at 1200 °C and 1250 °C TC, clay was subjected to warping and exhibited lower bending strength than RC clay due to bubble defects or bloating evenly distributed both inside the clay body and on the surface. EDX analysis showed that the defect areas contained a very high level of potassium, suggesting that they were initially coarse microcline particles. When TC clay was pretreated by ball-milling, the defects disappeared and the bending strength was significantly improved.

KEYWORDS: Clay, Defects, Strength, Vitrification.

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