In-situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite

Tezuka, N; Low, IM; Davies, IJ; Prior, MJ; Studer, AJ

In-situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite

Date

2005-11-27

Authors

Publisher

The Bragg Institute, Australian Nuclear Science and Technology Organisation

Abstract

“Kaolin” is a major raw material for the fabrication of conventional ceramics. Whilst kaolin has been thoroughly studied in the past decades with regards to its application as conventional ceramics there has been renewed interests in the conversion of kaolin to mullite (3Al2O3,2SiO2) with purpose of furthering the understanding of processing advanced ceramics with high strength, toughness, and thermal stability. One of the advantages of kaolin as a starting material is the needle-like morphology of mullite that is obtained by the transformation sequence at elevated temperature: kaolin —> metakaolin —> Al-Si spinel —> primary mullite (2Al203.SiO2) —> secondary mullite (3Al2O3.2SiO2). The ratio of Al203/SiO2 in mullite is considered to change by the replacement of Al and Si atoms in the tetrahedral positions. However, the in-situ transformation of primary to a secondary mullite has not been investigated in detail. This paper investigates the thermal phase transformation of mullite from two different types of kaolin (kaolinite and halloysite) with or without AIZO3 matrix constraint through the heating and cooling process by in-situ neutron diffraction. The effects of starting materials and heat treatment on the mullitisation process, especially in terms of primary —> secondary mullite evolution, are highlighted and discussed. © 2005 The Authors

Description

The paper has also been presented as Abstract T160 on page 237 which appears to be a duplication of item T158. Physical copy held by ANSTO Library at DDC 539.7217/2

Keywords

Kaolin, Raw materials, Ceramics, Mullite, Fracture properties, Phase transformations, Neutron diffraction

Citation

Tezuka, N., Low, I. M., Davies, I. J., Prior, M., & Studer, A. (2006). In situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite. Paper presented at the Eighth International Conference on Neutron Scattering ICNS 2005: "Neutrons for structure and dynamics - a new era", Sydney Convention & Exhibition Centre, Sydney, Australia, 27 November-2 December 2005. In Final Programme and Abstract Book, (pp. 236).