J. Korean Ceram. Soc. > Volume 49(6); 2012 > Article
 Journal of the Korean Ceramic Society 2012;49(6): 586. doi: https://doi.org/10.4191/kcers.2012.49.6.586
 Zr2WP2O12 세라믹스의 합성과 소결거동 연구 김용현, 김남옥, 이상진 국립목포대학교 신소재공학과 Synthesis and Sintering Behavior of Zr2WP2O12 Ceramics Yong-Hyeon Kim, Nam-Ok Kim, Sang-Jin Lee Department of Advanced Materials Science and Engineering, Mokpo National University ABSTRACT $Zr_2WP_2O_{12}$ powder, which has a negative thermal expansion coefficient, was synthesized by a solid-state reaction with $ZrO_2$, $WO_3$ and $NH_4H_2PO_4$ as the starting materials. The synthesis behavior was dependent on the solvent media used in the wet mixing process. The $Zr_2WP_2O_{12}$ powder prepared with a solvent consisting of D. I. water was fully crystallized at $1200^{circ}C$, showing a sub-micron particle size. According to the results obtained from a thermal analysis, a $ZrP_2O_7$ was synthesized at a low temperature of $310^{circ}C$, after which it was reacted with $WO_3$ at $1200^{circ}C$. A new sintering additive, $Al(OH)_3$, was applied for the densification of the $Zr_2WP_2O_{12}$ powders. The cold isostatically pressed samples were densified with 1 wt% $Al(OH)_3$ additive or more at $1200^{circ}C$ for 4 h. The main densification mechanism was liquid-phase sintering due to the liquid which resulted from the reaction with amorphous or unstable $Al_2O_3$ and $WO_3$. The densified $Zr_2WP_2O_{12}$ ceramics showed a relative density of 90% and a negative thermal expansion coefficient of $-3.4{times}10^{-6}/^{circ}C$. When using ${alpha}-Al_2O_3$ as the sintering agent, densification was not observed at $1200^{circ}C$. Key words: $Zr_2WP_2O_{12}$, Thermal expansion, Sintering, $Al_2O_3$, $Al(OH)_3$, Microstructure
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