Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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Fabrication of Mullite Short Fibers from Coal Fly Ash

석탄회로부터 뮬라이트 단섬유의 제조

  • Kim, Byung-Moon (School of Materials Science and Engineering, Pusan National University) ;
  • Park, Young-Min (School of Materials Science and Engineering, Pusan National University) ;
  • Lyu, Seung-Woo (School of Materials Science and Engineering, Pusan National University) ;
  • Yoon, Seog-Young (School of Materials Science and Engineering, Pusan National University) ;
  • Park, Hong-Chae (School of Materials Science and Engineering, Pusan National University)
  • Published : 2006.04.01
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Abstract

Mullite short fibers have been fabricated by adapting the Kneading-Drying-Calcination (KDC) process and characterized. The effect of the addition of foaming agent and calcination temperature on the formation of mullite fibers from coal fly ash, was examined. In the present work, ammonium alum $NH_4Al(SO_4)_2\;12H_2O$ synthesized trom coal fly ash and sodium phosphate $Na_2HPO_4\;2H_2O$ were used as foaming agents. After calcination at $1300^{\circ}C$ for 10 h and then etching with 20% HF solution at $50^{\circ}C$ for 5 h using a microwave heating source, the alumina-deficient $(AI_2O_3/SiO_2$ = 1.13, molar ratio) orthorhombic mullite fibers with a width of ${\sim}0.8mm$ (aspect ratio >30), were prepared from the coal fly ash with $AI_2O_3/SiO_2$ = 0.32, molar ratio by the addition of $NH_4AI(SO_4)_2\;12H_2O$, and with further addition of 2 wt% sodium phosphate. The excessive addition of sodium phosphate rather decreased the formation of mullite fibers, possibly due to the large amount of liquid phase prior to mullitization reaction.

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References

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