SHEN Zongyang, LI Yueming, WANG Zhumei, CHENG Ye,LIU Zhi, WU Fen

(School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Key Laboratory of Advanced Ceramics of Jiangxi Province, Jingdezhen Jiangxi 333001, China)

Abstract:Kaolin samples were collected from Bainacun in Dafang, Guizhou, then ball-milled and screened through an 80-mesh sieve for analysis. The chemical composition, mineral composition, physicochemical properties and microstructure of the kaolin were characterized by XRF, XRD, DTA-TG, FE-SEM and TEM. Various processing properties of the clay were detailedly investigated. The results indicate that the main mineral composition of the kaolin includes halloysite (84.77wt%) and nontronite (1.33wt%). It is of typical hexagonal tubular structure. The tube diameter was about tens or dozens of nanometers, while the tube length was about hundreds of nanometers. The kaolin shows good plasticity, very high cation exchange capacity, less liquidity and thixotropy, large drying shrinkage and low drying strength. Meanwhile, its low Fe2O3 (0.43wt%) content leads to high firing whiteness, which reaches 70.8% when fired at 1250℃.

Key words: kaolin; halloysite; cation exchange capacity; whiteness; Guizhou