Synthesis and Properties of Mullite from Kaolin by Boehmite Gel Coating

Boehmite Gel Coating법에 의한 Kaolin으로부터 Mullite의 합성 및 그 특성

In order to apply synthesis technique of the high purity ceramic powder to the traditional ceramic powder, mullite powder which is widly used for refractory materials was synthesized. Boehmite and Hadong kaolin with high alumina content were used as starting materials and gel coating method was tried to produce the mullite powder. As a result, the mullite powder of high quality was successfully obtained at 1350℃. The unreacted silica and cornudum were not observed in the synthesized mullite powder, mullite content was more than 80% when the starting materials were sintered at 1700℃. Their properties showed bulk specific gravity of 2.56, water absorption of 1.9%, and 3-point flexual strength of 169 MPa. It is thought that that their good properties are applicable to refractory materials of high quality.

본 연구는 fine ceramics의 합성법을 traditional ceramics의 합성에 적용하는 연구의 일환으로 내화재료용 mullite합성법을 개발하고자 한다. 출발원료로는 알루미나 함량이 높은 하동 kaolin 과 boehmite를 사용하였으며 합성법은 gel coating법을 사용하였다. 그 결과 1350℃에서 미반응 silica와 corundum이 존재하지 않는 단일상의 mullite를 합성할 수 있었으며 1700℃로 소성한 분말의 경우 mullite 생성율은 80%로 나타났다. 이 때 부피비중은 2.56, 흡수율은 1.9%, 상온꺽임강도는 169 MPa의 값을 나타내어 우수한 내화재료로의 활용이 가능하다고 생각된다.