MIAO Lifeng, BAO Zhenhong, JIANG Weihui

(The National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic Institute, Jingdezhen 333001, Jiangxi, China )

Abstract: The influences of the calcining temperature on the whiteness and sintering properties were studied using Longyan, Lincang and Xingzi kaolins as materials. The results show that the whiteness of the three kaolins decreased slightly when calcined at 200~600 °C; when calcined at 600~1400°C, their whiteness increased to the highest value (the optimal calcining temperatures for Longyan, Lincang and Xingzi kaolins were respectively 1100 ℃, 1200 ℃ and 1300 ℃) and then decreased. The whiteness of Xingzi kaolin was much lower than those of Longyan and Lincang due to its high content of Fe₂O₃ and its whiteness reduced obviously due to the formation of more iron olored compounds. Longyan kaolin had the lowest refractoriness due to its high content of K₂O, which led to the lowest temperature for reaching the maximum whiteness, and its water absorption was only 0.29% when calcined at 1400 ℃. Up until 1200 ℃, Lincang kaolin had the maximum firing shrinkage due to its high loss on ignition. At 1300 ℃, the firing shrinkage of Longyan kaolin, with its good sintering degree, was bigger than that of Lincang kaolin. Xingzi kaolin had the least firing shrinkage due to its highest refractoriness and coarse particles.

Key words: kaolin; whiteness; sintering property