천일염 열처리에 사용된 고순도 뮬라이트 용기에 대한 반응거동 고찰 |
배영주1, 정숙인2, 김남일2, 함경식3, 이상진1,2,* |
1목포대학교 신소재공학과 2목포대학교 세라믹산업기술연구소 3목포대학교 식품공학과 |
Reaction Behavior of High-purity Mullite Container with Melted Solar Salts |
Yeong-Ju Bae1, Suk-In Jeong2, Nam-Il Kim2, Kyung-Sik Ham3, Sang-Jin Lee1,2,* |
1Department of Advanced Materials Science and Engineering, Mokpo National University, Muan 58554, Republic of Korea 2Research Institute of Ceramic Industry and Technology, Mokpo National University, Muan 58554, Republic of Korea 3Department of Food Engineering, Mokpo National University, Muan 58554, Republic of Korea |
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Received: 28 June 2016; Accepted: 21 September 2016. Published online: 3 March 2017. |
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ABSTRACT |
High-purity and good sinterable mullite powder (3Al2O3・2SiO2) was synthesized by a sol-gel process to prepare a high-purity mullite crucible. The densified mullite crucible was fabricated by slip casting with the powder followed by sintering at 1600 ℃. Solar salt was put into the mullite crucible and then fired at the temperature of 1000 ℃ and 1250 ℃ with 4~24 h holding time. The inside surface of the crucible which was in contacted with the melted salt was analyzed using XRD, SEM and EDS. Corrosion of the crucible by the melted solar salt was insignificant. The reacted surface area displayed mullite, spinel and forsterite crystal phases, with a very thin reactant layer of 10~20 μm. The EDAX result of the very thin surface layer showed a relatively higher Na and Mg contents in the sample heat-treated at 1250 ℃ for 4 h compared to the sample heat-treated at 1000 ℃ for 24 h. EDS mapping showed that the reactant layer are mainly consisted of MgO, SiO2 and Al2O3. From these results, it can be speculated that mullite is attacked by the Mg component in the solar salt, rather than Na and S. Finally, the very thin reactant layer of the mullite surface at high temperature means that a pure mullite crucible can be used as a commercial ceramic container for the firing of solar salt. |
Keywords:
mullite, sol-gel process, solar salt, reaction behavior, crystal phase |
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