Bi계 압전세라믹을 이용한 자동차용 노킹센서의 제조와 응용

Alternative Title
Fabrication and Application of Automobile Knocking Sensor with Bi based Piezoelectric Ceramics
Alternative Author(s)
Kim, Yong Hyun
일반대학원 재료공학과
The Graduate School, Ajou University
Publication Year
본 연구에서는 Bi(Na,K)TiO₃의 압전물성, 전기기계 결합계수에 미치는 첨가물의 영향을 밝히고자 (Bi0.5Na0.5TiO3-Bi_(0.5)Na_(0.5)TiO₃ : 이하 _(x)BNT-_(1-x)BKT)를 기본 조성으로 여기에 천이금속화합물(A, B), SrTiO₃ 등의 여러 가지 첨가물을 첨가 및 치환하여 그에 의한 결정구조, 전기기계 결합계수의 변화와 미세구조 변화를 조사하였다. BNT_(x)-BKT_((1-x))(x=0.82~0.88) 조성에서 x=0.86의 유전율과 Tc가 가장높았으며 상온에서의 유전율은 471, Tc는 390℃이며, _((1-x))BNKT-_(x)SrTiO₃(x=0.01~0.07) 조성은 x=0.03 SrTiO₃가 치환되었을때 유전율과 Tc는 837, 280℃이다. 이와같이 ST의 첨가함으로서 유전율은 증가하고, Tc는 첨가량이 증가할수록 낮아지는 경향을 보였다. _(x)BNT-_((1-x))BKT(x=0.86) 조성의 기계적 품질계수인 Q_(m) 과 전기기계결합계수 k_(p)는 각각 205, 30%이다. 여기에 천이금속화합물(A, B)을 1wt% 첨가하게 되면 Q_(m) and k_(p) 는 400~500, 31~32%로 증가하게된다. 전기기계결합계수는 비슷하나 기계적 품질계수가 2배이상 증가하는 것으로 나타난다.
Alternative Abstract
In this research, the structure-processing-properties relations of BNT and solid solutions of BNT-BKT with Ni, Mn, ST were assessed. These modified BNT-BKT compositions were formulated by the conventional mixed oxide method, following optimized powder processing, specimen fabrication, and sintering procedures. A series of the modified BNT-BKT piezoceramics encompassing various dielectric and piezoelectric properties was prepared by the addition of three rare-earth ions. These modified BNT composition were calcined in the range of 900℃ for 1-2hr and then sintered at 1100℃ for 2-4hr. Conventional poling was performed at 110℃ with an applied field of 3-4 kV/mm for 20-30 minutes. The dielectric constant of BNT_(x)-BKT_((1-x))(x=0.86) ceramic is 471 and Curie temperature is 390℃ with the dielectric constant of 7268 and (BNT-BKT)_((1-x))-ST_(x)(x=0.03) ceramic is 837 and Curie temperature is 280℃ with the dielectric constant of 8243. ST addition, the Curie temperature, Tc, decreases rapidly with increasing amount of doped ST. The mechanical quality factor Q_(m) and electromechanical coupling factor k_(p) of BNT_(x)-BKT_((1-x))(x=0.86) ceramic are very high 205 and 30%. Ni, Mn addition, Q_(m) and k_(p) of (Ni, Mn x=1wat%) 450, 510 and 31%, 32% high. The k_(p) value (30%) of BNT_(x)-BKT_((1-x))(x=0.86) ceramic is similar to Ni, Mn addition ceramic, but the Q_(m) value is very high compared to BNT_(x)-BKT_((1-x))(x=0.86) ceramics.

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Graduate School of Ajou University > Department of Material Engineering > 3. Theses(Master)
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