Effects of Heat-Treatment Temperature on the Properties of Negative CTE Eucryptite Ceramics

Abstract:

In this paper, negative thermal expansion coefficient eucryptite powders were prepared by sol-gel method using silica-sol as starting material. The raw blocks were obtained by dry pressing process after the powder was synthesized, and then the raw blocks were heat-treated at 600º, 1150º, 1280º, 1380º, 1420º and 1450°C, respectively. Variations of density, porosity and thermal expansion coefficient at different heat treatment temperatures were investigated. Phase transformation and fracture surface morphology of eucryptite heat-treated at different temperatures, respectively, were observed by XRD and SEM. The results indicate that, with the increasing heat- treatment temperature, the grain size and the bending strength increased, porosity decreased, thermal expansion coefficient decreased continuously. Negative thermal expansion coefficient of -5.3162×10-6~-7.4413×10-6 (0~800°C) was obtained. But when the heat-treatment temperature was more than 1420°C, porosity began to increase, bending strength began to decrease, which were the symbols of over-burning, while the main crystal phase didn’t change.

• Periodical: Advanced Materials Research (Volumes 105-106)
• Pages: 123-125
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.105-106.123
• Online since: April 2010
• Authors: Yong Li, Qi Hong Wei, Ling Li, Chong Hai Wang, Xiao Li Zhang, Fang Gao
• Keywords: Eucryptite, Heat Treatment Temperature, Thermal Expansion Coefficient

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