为监测在役混凝土结构在使用过程中的内部缺陷程度变化并定位缺陷位置, 本文探索一种基于应力波的探测方法并进行试验研究, 将压电传感器(PZT)以阵列形式安装在混凝土表面, 将混凝土划分为不同区域, 阵列中的一个传感器发射波, 另一个传感器接收波, 采用扫频模式和五峰值脉冲模式对混凝土不同区域进行监测。试验结果表明, 当应力波通过待监测区域时, 由于混凝土内部存在缺陷, 应力波幅值衰减, 波能降低。为了量化混凝土结构内部缺陷程度, 构造基于接收信号的能量指数和损伤指数, 并分别建立其与缺陷程度的函数关系, 依据不同区域能量指数和损伤指数差异, 确定混凝土内部缺陷存在的区域。试验结果与试件实际情况相吻合, 验证了本文采用压电传感器监测混凝土内部缺陷的可行性。

高性能环境友好型(K,Na)NbO3(KNN)基无铅压电陶瓷是国际上功能陶瓷的重要科学前沿和技术竞争焦点之一。优异的压电性能及其温度稳定性、抗疲劳特性、力学性能以及制备工艺重复性等综合性能是KNN基陶瓷有望得以广泛应用的重要前提, 而这些性能与KNN基陶瓷的多层次结构紧密相关。本工作从多层次结构调控的角度出发, 总结了KNN基陶瓷压电性能与其温度稳定性、抗疲劳特性、力学性能、制备工艺重复性研究等方面的研究进展以及KNN基陶瓷的应用技术研究进展。最后, 就KNN基无铅压电陶瓷的未来发展进行展望。

In this paper, a comprehensive study of microstructure/properties interrelations for porous piezoceramics based on PZT composition was performed. Experimental samples of porous piezoceramics were fabricated using a modified method of burning-out a pore former. Porosity dependencies of elastic, dielectric, piezoelectric and electromechanical coefficients of the porous ceramics in the relative porosity range 0-50% were obtained and analyzed. As a result of microstructure analysis, it was found that at any connectivity type (3–0, 3–3) and porosity up to 50% the real structures of porous piezoceramics were close to the matrix medium structure with continuous piezoceramic skeleton. It was also revealed that the microstructural features of porous piezoceramics define the character of the dependences of the dielectric, piezoelectric and electromechanical properties of porous piezoelectric ceramics on porosity. In conclusion, microstructure/properties interrelations, as well as new applications of porous piezoceramics were discussed.In this paper, a comprehensive study of microstructure/properties interrelations for porous piezoceramics based on PZT composition was performed. Experimental samples of porous piezoceramics were fabricated using a modified method of burning-out a pore former. Porosity dependencies of elastic, dielectric, piezoelectric and electromechanical coefficients of the porous ceramics in the relative porosity range 0-50% were obtained and analyzed. As a result of microstructure analysis, it was found that at any connectivity type (3–0, 3–3) and porosity up to 50% the real structures of porous piezoceramics were close to the matrix medium structure with continuous piezoceramic skeleton. It was also revealed that the microstructural features of porous piezoceramics define the character of the dependences of the dielectric, piezoelectric and electromechanical properties of porous piezoelectric ceramics on porosity. In conclusion, microstructure/properties interrelations, as well as new applications of porous piezoceramics were discussed.

In this paper, the results of experimental study of dispersion characteristics of complex electromechanical parameters of ferroelectrically “hard” porous piezoceramics based on PZT composition were presented. Experimental samples of porous piezoceramics were fabricated using a modified method of burning-out a pore former. The complex constants of porous piezoceramics with relative porosity 16% and their frequency dependences were measured using the piezoelectric resonance analysis method. As a result of experimental studies, regions of elastic, piezoelectric and electromechanical dispersion, characterized by anomalies in the frequency dependences of the imaginary and real parts of the complex constants of porous piezoelectric ceramics were found. It was revealed also that the microstructural features of porous piezoceramics determine the character of frequency dependences of complex electromechanical parameters of porous piezoelectric ceramics. In conclusion, the microstructural and physical mechanisms of electromechanical losses and dispersion in porous piezoceramics were discussed.In this paper, the results of experimental study of dispersion characteristics of complex electromechanical parameters of ferroelectrically “hard” porous piezoceramics based on PZT composition were presented. Experimental samples of porous piezoceramics were fabricated using a modified method of burning-out a pore former. The complex constants of porous piezoceramics with relative porosity 16% and their frequency dependences were measured using the piezoelectric resonance analysis method. As a result of experimental studies, regions of elastic, piezoelectric and electromechanical dispersion, characterized by anomalies in the frequency dependences of the imaginary and real parts of the complex constants of porous piezoelectric ceramics were found. It was revealed also that the microstructural features of porous piezoceramics determine the character of frequency dependences of complex electromechanical parameters of porous piezoelectric ceramics. In conclusion, the microstructural and physical mechanisms of electromechanical losses and dispersion in porous piezoceramics were discussed.

以Pb(Ni1/3Nb2/3)O3-Pb(Zr0.41Ti0.59)O3(PNN-PZT)为基础体系, 通过对烧结助剂x%CuO(质量比)和y%LiBiO2(质量比)的质量进行调节, 对陶瓷样品的相结构、微观组织形貌及电学性能进行了分析, 阐述了助烧剂对陶瓷样品性能的影响。结果发现, 在温度940~960 ℃下陶瓷烧结成瓷, 且晶粒长大较充分。当x =0.2, y =1时, 陶瓷样品的电学性能最优, 即此时压电常数d33 =608 pC/N, 机电耦合系数kp=0.65, 介电损耗tan δ =2.19%, 介电常数εr=3 843。采用烧结助剂质量比x=0.2,y=1的粉体制备7 mm×7 mm×36 mm的叠层压电驱动器, 然后进行微观组织形貌和位移特性研究。叠层压电驱动器断面微观结构表明, 电极层与陶瓷层粘接紧密, 无裂缝或间隙产生。位移的测试结果表明, 随着电压的增加, 位移也在逐渐增加, 在驱动电压为150 V时, 其最大位移为46.280 μm, 位移增大的同时, 迟滞逐渐降低。

针对新一代声波测井仪器对其核心元件压电陶瓷兼具高居里温度、高压电系数以及高稳定性要求的迫切需求, 本文采用传统的固相反应-无压烧结技术制备了一种0.06BiYbO3-0.94Pb(Zr0.48Ti0.52)O3(BY-PZT)三元系压电陶瓷, 并研究了四种氧化物掺杂对其微观结构及电学性能的影响。由XRD和SEM表征可知所有样品均呈纯四方相钙钛矿结构, 掺杂Cr2O3的样品平均晶粒尺寸最大。介电温谱和谐振频谱研究证实四种氧化物掺杂均能提高其介电性能的温度稳定性。掺杂La2O3的样品介电常数温度系数(Tkε)最低, 掺杂MnO2的样品机械品质因素(Qm)最高, 而掺杂CeO2的样品抗热退极化性能最好。高温复阻抗(Cole-Cole图)分析表明, Cr2O3掺杂能够显著提高BY-PZT陶瓷的高温电阻率, 陶瓷在高温下的电导行为主要由晶界响应控制。综合来看, 掺杂La2O3的样品兼具高居里温度(TC=397 ℃)和高压电系数(d33=290 pC/N), 并且在300 ℃退火4 h后d33仍能保持在270 pC/N左右, 有望在极限工作温度为300 ℃的高温压电器件中获得应用。

为研究超声悬浮轴承的静、动态承载特性, 设计了一种压电陶瓷驱动的全包围结构超声悬浮轴承。分析了气体挤压膜润滑承载机理,在等温隔热条件下, 根据牛顿流体的气体动力学理论, 建立了描述轴承启动阶段及支撑回转体稳定旋转阶段气膜压力的静、动态雷诺方程。采用有限差分法并利用MATLAB自定义函数的功能, 对超声悬浮轴承的静态及动态承载力进行了数值计算。为验证理论计算的正确性, 通过轴承样机自悬浮实验验证轴承悬浮特性的理论计算结果, 得出在其谐振频率下, 相同结构尺寸及悬浮参数的轴承静态承载力理论计算值与测量值之间的误差为8.33%; 在挤压数为100, 2~5 μm合理初始间隙下, 动态悬浮力理论计算值与实验测量值相吻合。考虑样机结构特性引起的能量转换误差及实验环境因素影响, 误差在合理允许范围之内, 验证了理论分析及计算的正确性,对超声悬浮轴承的理论研究及设计具有一定的指导意义。

为实现低频率,高强度的振动能量回收和利用,提出一种基于压电流体耦合作用的压电晶片式液压发电装置。通过理论分析设计结构,采用直径60 mm,厚度1.6 mm的压电晶片以及直径16 mm,高度50 mm的液压缸制作样机,用水作为工作介质,测试了装置在不同激励频率、激励电压、系统背压及加载质量等条件下的电压输出情况。试验结果表明:当激励频率(工作频率)在27 Hz左右时,该压电晶片式液压发电装置的输出电压达到最大,且在一定的范围内,发电装置输出电压随着激励电压、系统背压及加载质量的增加而增加,验证了液压-压电发电的可行性。