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Pore evolution and microstructure during the burnout and sintering process in BaTiO₃based Ni-MLCCs 원문보기

  • 저자

    Kang, Kyung-Moo

  • 학위수여기관

    昌原大學校

  • 학위구분

    국내석사

  • 학과

    材料工學科

  • 지도교수

  • 발행년도

    2003

  • 총페이지

    xv, 101장.

  • 키워드

  • 언어

    eng

  • 원문 URL

    http://www.riss.kr/link?id=T8935830&outLink=K  

  • 초록

    Tape casting법으로 제조된 MLCCs를 burnout 공정에서 burnout온도,분위기, heating rate에 따른 pore 구조, 크기와 burnout미세구조의 영향 및 burnout공정과 소결공정에서 heating rate의 profile에 따른 기공진화 및 소결미세구조에 미치는 영향을 고찰하였다. Burnout공정의 산화분위기에서 MLCCs의 delamination는 200℃의 7℃/min, 250℃와 300℃의 6℃/min의 heating rate에서 얻을 수 있었다. MLCCs의 기공크기분포는 burnout 온도와 heating rate가 증가함에 따라 기공분포가 좁아지며, 축적된 기공표면적은 산화와 환원분위기에서 높은 burnout온도와 heating rate에서 최소값을 얻었다. 특히, 환원분위기에서의 MLCCs는 산화분위기보다 작은 축적된 기공표면적을 얻었다. burnout 공정 후 미세구조는 heating rate보다 분위기와 burnout온도에 의존함을 알 수 있었다. Heating rate(1℃/min,3℃/min,5℃/min)에 의해 소결된 MLCCs의 기공크기분포는 소결온도가 증가함에따라 점차적으로 좁아지며, 기공진화와 관련 된 축적된 기공표면적은 소결온도가 증가함에따라 최소값을 얻었다. heating rate 변화에 따라 소결된 MLCCs의 미세구조는 느린 heating rate에서 효과적으로 치밀화 되었다. burnout 공정에서 heating rate는 소결공정에서의 heating rate보다 미세구조와 기공진화에 큰 영향을 주었다.


    BaTiO₃ based multilayer ceramic capacitors (MLCCs) prepared by tape casting, showing X7R and Y5V characteristic, were fired with different burnout and with heating profile in the burnout and sintering processes. Also, the effects of the burnout processes and the heating profile in burnout and sintering processes, on pore structure, burnout microstructure, pore evolution in the multiplayer ceramic capacitors (MLCCs) showing X7R and Y5V characteristic, were investigated to optimize the fabrication process. In the different burnout conditions, the pore size distribution of MLCCs becomes narrower with increasing in temperature and heating rate, showing larger pore size and mono-modal pore size distribution. The cumulative pore surface area shows minimum values at higher temperature and at faster heating rate in both atmospheres. However, MLCCs of the reducing atmosphere display smaller cumulative pore surface area than that of the ambient atmosphere. The green microstructure related to the burnout process is more dependent on the burnout atmosphere and temperature than the heating rate. MLCCs were sintered under various conditions, at heating rates of 1℃/min, 3℃/min, and 5℃/min in both processes with and without the holding time at the sintering temperature. The pore size distribution and cumulative pore surface area became broad and small, respectively, as the heating rate and sintering temperature were increased. The heating rate and the sintering temperature also affected hysteresis between the mercury intrusion/extrusion behaviors. The microstructure revealed that the MLCCs were effectively densified in the slow heating rate, indicating that full densification would be achieved at the heating rate of 1℃/min with the holding time of 3 hours. The heating rate in the burnout process predominantly affected the pore evolution and microstructure more so than that in the sintering process, showing the effects of the holding time on removing the residual pores and on developing the final microstructure.


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