Toughening of bismuth-based lead-free piezoceramics

铋基无铅压电陶瓷的增韧

基本信息

批准号：
229436520
负责人：
Professor Dr.-Ing. Jürgen Rödel
金额：
--
依托单位：
Fachgebiet Nichtmetallisch-Anorganische Werkstoffe
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/229436520?language=en
关键词：
Toughening bismuth based lead free

项目摘要

Multilayer actuators are often subjected to temperatures up to 150 oC and are susceptible to crack propagation emanating from internal electrode edges. Replacement of lead-containing piezoceramics through lead-free piezoceramics therefore requires knowledge of salient mechanical properties like temperature-dependent crack propagation. Amongst the new materials, bismuth-based piezoceramics have been shown to exhibit strains in excess of lead zirconate titanate based on field-induced ferroelectric order. These materials exhibit phase diagrams with ergodic and nonergodic relaxor as well as ferroelectric phases. The transitions between relaxor and ferroelectric have recently been identified to depend on electric field, as already known, for example for PMN-PT. BNT-BT BT (bismuth sodium titanate-barium titanate) materials have also been proven to exhibit phase transitions dependent on mechanical stress. Therefore, in this proposal, the crack propagation is to be studied for BNT-BT compositions with different dopant content in the prospective temperature regime to access both ergodic and nonergodic relaxors as well as ferroelectrics. The focus will be on materials where the transition from relaxor to ferroelectric has been completed either reversibly or irreversibly in a crack-tip process zone with attendant ferroelastic toughening with the bulk remaining untransformed. This transition will further be quantified by determining stress-strain curves including volume change as function of temperature. Exemplary in-situ neutron and synchrotron diffraction under uniaxial stress and under crack propagation conditions will be used to rationalize the toughening effect and the ensuing R-curve behavior.

多层执行器通常会经受高达150 oC的温度，并且容易受到内部电极边缘发出的裂纹传播的影响。因此，通过无铅的压电陶瓷取代含铅的压电陶瓷需要了解显着的机械性能，例如温度依赖性裂纹的传播。在新材料中，基于野晶式的压电陶瓷显示出基于野外诱导的铁电序的含铅钛酸钛酸盐的菌株。这些材料具有梯形和非癌变宽松以及铁电相的相图。最近已经确定了放宽器和铁电之间的过渡以取决于电场，例如，PMN-PT已知。 BNT-BT BT（二苯甲酸氢钠钛酸钠）材料也已被证明可以表现出取决于机械应力的相变。因此，在此提案中，应研究裂纹的繁殖，用于前瞻性温度方案中具有不同掺杂剂含量的BNT-BT组成，以访问ergodic和非癌变松弛剂以及铁电极。重点将放在材料上，在这种材料上，从松弛剂到铁电的过渡已在裂纹尖端过程区域内可逆或不可逆转地完成，而随之而来的铁弹性韧性则进行了散装，但仍未转换。通过确定应力 - 应变曲线，包括体积变化作为温度功能，将进一步量化此转换。在单轴应力和裂纹传播条件下，示例性的原位中子和同步加速器衍射将用于合理化韧性和随之而来的R-curve行为。