Application of Bulk Talc to Molding Material

주형재료로서 덩어리 활석의 이용

  • Ha, Man-Jin (Dept. of Metallurgical Eng., KAIST) ;
  • Lee, Zin-Hyoung (Dept. of Metallurgical Eng., KAIST) ;
  • Lee, Sang-Soo (Lab. of Conservational SCi, National Museum) ;
  • Eun, Hee-Joon (Dept. of Mechanical Research, Korea Research Institute of Standards and Science)
  • 하만진 (한국과학기술원 재료공학과) ;
  • 이진형 (한국과학기술원 재료공학과) ;
  • 이상수 (국립박물관 보존과학실) ;
  • 은희준 (한국표준연구원 역학연구부)
  • Published : 1994.02.28

Abstract

The possibility of using bulk talc as molding material was reviewed and tested with the measurement of thermal properties and computer simulations. The measured thermal conductivity and heat diffusivity($k{\rho}c$) of talc were $2.4W/m^{\circ}C$ and $6.6{\times}10^6J^2/m^4^{\circ}C^2s$, respectively. Thermal properties of talc could be ranked between those of sand mold and iron mold. Talc transforms into cristobalite and enstatite at $910^{\circ}C$, During the transformation volume and structure change, cracks appear on the surface and distortion occurs. Therefore talc can be used for molding material below $910^{\circ}C$ if carefully treated. Computer simulation was carried out to test whether talc insert could promote directional solidification in sand mold and iron mold. In sand mold, it was possible to achieve directional solidification of thin plate casting with the length to thickness ratio of 15, if both iron insert and talc insert were used. In iron mold, it was possible to achieve directional solidification only with talc insert.

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