Economic and Environmental Geology (자원환경지질)

The Korean Society of Economic and Environmental Geology (대한자원환경지질학회)
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Interpretation of Firing Temperature and Thermal Deformation of Roof Tiles from Ancient Tombs of Seokchon-dong in Seoul, Korea

서울 석촌동 고분군 출토 기와의 소성온도와 열변형 특성 해석

  • Jin, Hong Ju (Conservation Science Division, National Research Institute of Cultural Heritage) ;
  • Jang, Sungyoon (Cultural Heritage Conservation Science Center, National Research Institute of Cultural Heritage) ;
  • Lee, Myeong Seong (Conservation Science Division, National Research Institute of Cultural Heritage)
  • 진홍주 (국립문화재연구소 보존과학연구실) ;
  • 장성윤 (국립문화재연구소 문화재보존과학센터) ;
  • 이명성 (국립문화재연구소 보존과학연구실)
  • Received : 2021.10.05
  • Accepted : 2021.11.06
  • Published : 2021.12.28
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Abstract

This study investigated the firing temperature and thermal deformation process of roof tiles excavated from the connected stone-mound tomb in Seokchon-dong, Seoul, based on mineralogical and physical properties. A large number of roof tiles were excavated from the tomb site and some roof tiles were deformed by heat and were fired in uneven conditions. The colors of original roof tiles and their cores are mostly yellowish-brown, with high water absorption over 12%, containing fine-grained textures and some minerals such as quartz, feldspars, amphibole, and mica. It is estimated that the original roof tiles were fired below 900℃ in oxidation condition, showing loose matrices and mica layers by scanning electron microscopy. However, deformed roof tiles have the uneven surface color of reddish-brown and bluish-gray, and those cross-sections have sandwich structures in which dense reddish-brown surface and porous grey core coexist. They contained mullite and hercynite, so it was estimated to have been fired over 1,000℃, with 0.81~11% water absorption. In some samples, bloating pores by overfiring were observed, which means that they were fired at more than 1,200℃. In addition, the refirng experiments that the original roof tile was fired between 800℃ and 1,200℃ were carried out to investigate the physical and mineralogical properties of roof tiles compared to deformed ones. As a result, the water absorption decreased rapidly and the mineral phase started to change over 1,000℃. As the temperature gradually rises, the matrices are partially melted and recrystallized, resulting in similar thermal characteristics of deformed roof tiles. Therefore, the roof tiles from ancient tombs in Seokchon-dong seem to experience the secondary high temperature of 1,000 to 1,200℃ under uneven firing conditions, resulting in deformation characteristics such as shape transformation and mineral phase transition. It is considered to have been related to cremation rituals at the tombs of Seockchon-dong during the Baekje period.

이 연구에서는 서울 석촌동 고분군 연접적석총에서 출토된 기와의 물리적 및 광물학적 특성을 바탕으로 소성온도를 추정하고, 열변형 과정을 해석하였다. 석촌동 고분군에서는 다량의 기와가 출토되었는데, 일부 기와는 열에 의해 형태가 변하고 불균일한 소성상태를 나타냈다. 원형기와의 표면과 속심의 색조는 비교적 균일한 황갈색 계열로서 약 12% 이상의 높은 흡수율을 나타내며, 미정질 기질에 세립질 석영, 장석류, 운모, 각섬석 등을 포함한다. 또한 미세조직 관찰 결과, 느슨한 기질과 운모의 층상구조가 확인되어 900℃ 이하의 산화환경에서 제작되었을 것으로 추정된다. 반면 열에 변형된 기와는 주로 적갈색과 청회색의 불균일한 표면 색조를 보이며, 단면은 치밀한 적갈색 표면과 다공성의 자회색 내부기질이 함께 나타나는 샌드위치 구조를 나타낸다. 흡수율은 0.8~11%이며, 멀라이트, 헤르시나이트가 동정되어 소성온도가 1,000℃ 이상으로 추정된다. 일부 시료에서는 과소성에 의한 블로우팅 포어(bloating pore)가 관찰되었고, 1,200℃ 이상의 고온을 경험한 것으로 판단된다. 한편, 원형기와를 800~1,200℃ 사이에서 온도별로 재소성하여 물리적 및 광물학적 특성을 확인한 결과, 1,000℃ 부근에서 흡수율이 급격히 낮아지고 고온 광물이 생성되기 시작했다. 또한 점차 온도가 올라갈수록 기질이 부분 용융되고 재결정화되어 변형기와의 열변형 특성과 유사한 결과를 나타냈다. 따라서 석촌동 고분군 기와는 불균일한 소성상태와 1,000~1,200℃에 달하는 2차 고온을 경험하여 형태 변형, 광물 상전이 등의 열변형 특성이 발생하였고, 이는 백제시대 화장의례와 관계가 있는 것으로 생각된다.

Keywords

Acknowledgement

이 연구는 문화재청 국립문화재연구소 문화유산조사연구(R&D)의 일환으로 수행되었으며, 한성백제박물관의 시료 협조에 깊이 감사드린다.

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