PNN／PZT系梯度功能压电陶瓷离子互扩散动力学

研究了ＰＮＮ／ＰＺＴ系梯度功能压电材料中各类离子互扩散反应及其随温度和时间的变化。用电子探针测量了互扩散偶的组分分布，利用“薄板叠加”扩散模型，对Ｎｉ＾２＋、Ｎｂ＾５＋，Ｔｉ＾４＋和Ｚｒ＾４＋的扩散浓度分布曲线进行数值逼近计算，确定了互扩散层的厚度，估算了各离子的扩散系数及其表现激活能。     

PNN/PZT系梯度功能压电材料的离子互扩散

本文研究了PNN／PZT系梯度功能压电材料中,不同离子（Nb⁵⁺、Ni²⁺、Zr⁴⁺、Ti⁴⁺）的互扩散反应随扩散温度和扩散时间的变化规律．利用电子探计（EPMA）测量了离子的组份分布,确定了离子互扩散层的厚度．采用“薄板扩散叠加”模型,对Ni²⁺、Nb⁵⁺、Ti⁴⁺和Zr⁴⁺离子的组份分布进行了计算机数值模拟,结果与EPMA实验相吻合．估算了离子的扩散系数与表观激活能,并对此进行了讨论．     

晶体结构对压电陶瓷微位移驱动器特性的影响

对钙钛矿结构的ＰＺＴ－５和钨青铜结构的ＰＢＮＮ二种压电陶瓷制成的压电微位移器进行了电压－位移特性的比较和分析，发现我们所研制的ＰＢＮＮ压电微位移器具有线性好、回零好、等优点。     

PZT系多层片式压电陶瓷微驱动器位移性能研究

采用陶瓷坯膜流延成型和陶瓷坯膜／金属内电极共烧技术,制作了多层片式高含铅PZT软性压电陶瓷微驱动器．该器件具有体积小、工作电压低、位移量大（38V,1.05μm）的特点．本文对制作的多层片式器件在直流和单向交流工作电压的作用下产生的静态和动态位移特性,从PZT压电陶瓷材料的晶体和电畴结构特点进行了分析和研究．     

电阻率梯度PZT/ZnO压电复合陶瓷的结构与电性能

研制了具有电阻率和压电系数梯度的PZT/ZnO压电陶瓷,其本身也是一类独石型梯度功能压电陶瓷驱动器(FGMPA),并且它所需的驱动电场比La-PZT/Fe-PZT FGMPA低.分别用电子探针(EPMA)、X衍射(XRD)和扫描电镜(SEM)查证了其组分、相结构和显微结构的梯度分布.结果表明,显微结构及电性能的梯度分布,主要是由Zn2+的扩散及其在PZT晶界富集造成的,它也是使PZT层中与界面相邻的部分区域电阻率下降的原因.XRD证实了在PZT层中ZnO第二相的存在.     

具有压电元件的功能梯度弹性薄板的振动特性

考虑一功能梯度薄板,其上下表面嵌有压电执行元件。根据逆压电效应,将电场强度转换成作用于板上的等效电载荷。假设梯度材料的物性参数为板厚度方向坐标的幂函数,应用达朗贝尔原理,导出了具有压电元件的功能梯度弹性薄板的动力学方程。采用变量分离与Navier解,得到四边简支功能梯度板的固有特性与电场强度间的关系。并进一步通过数值例子讨论了电场强度、材料的梯度指数等对板固有特性的影响。研究结果表明,调整作用于执行元件上的电场强度可以实现对板的振动特性的控制,而材料的梯度化可影响板的固有频率,在设计中应予以考虑。     

含弹性基础压电功能梯度圆柱壳的振动分析

为分析多物理场下含双参数弹性基础压电功能梯度圆柱壳的自由振动特性,以含Pasternak-Winkler 弹性基础压电功能梯度圆柱壳为对象,采用1 阶剪切变形理论和Hamilton 变分原理推导多场作用下含弹性基础压电功能梯度圆柱壳的模态频率方程,讨论弹性基础参数、温度梯度、压电层的材料种类和功能梯度层的材料组分等对模态频率的影响。结果表明,模态频率随温度梯度的增大而减小,随陶瓷体积分数指数和弹性基础参数的增大而增大;选用BaTiO3时,圆柱壳的模态频率以及对温度梯度的敏感性均最大,而受外激励电压的影响最小;相较于外激励电压,温度梯度对模态频率影响较大。     

RAINBOW压电驱动器的制备及性能

ＲＡＩＮＢＯＷ压电驱动器是一种具有超大位移量和一定负载能力的新型压电驱动器。了在于铌锌锆钛酸铅压电陶瓷的ＲＡＩＮＢＯＷ器件,对其制备工艺进行了研究和探索,确定了合理的工艺参数和制备方法,成功地制备了拱形经 ＲＡＩＮＢＯＷ器件;研究了该器件的压电、位移、谐振以及铁电性能,根据实验认为制备得到手Ｒ ＡＩＮＢＯＷ器件,具有良好的位移性能,未极化的ＲＡＩＮＢＯＷ器件对于正负电场的响应（极化、位移） 存在不     

间隙波在功能梯度压电板和压电半空间结构中的传播

研究了间隙波在功能梯度压电板和压电半空间结构中的传播性质.功能梯度压电板的材料性能沿x2方向呈指数变化,首先推导了间隙波传播时的解析解,利用界面条件得到了间隙波的频散方程,基于推导的频散方程,结合数值算例分析了功能梯度压电材料的梯度、压电层厚度以及材料性能对间隙波相速度的影响,研究结果对功能梯度压电材料的覆层结构在声波器件中的应用具有重要的参考价值.     

梯度功能压电复合材料球壳的热弹性近似解

针对梯度功能压电复合材料球壳热弹性响应提出了简单而精确的近似解。借鉴纤维复合材料层合结构的研究方法，将梯度功能压电复合材料球壳沿径向分为若干层，各层视为均匀材料，从而导出力-电-温度多场耦合近似解。只要层数足够大，解将收敛于精确解。该方法的另一个优点在于解的方法对材料性能的变化方式（函数）没有要求，具有普适性。这对其它非均匀材料结构的分析具有推广、应用价值。     

Cu/ABS复合导电梯度功能材料的制备和性能

借助HAAKE转矩流变仪,采用熔融共混法制备了一系列Cu粉含量不同的Cu/丙烯腈-丁二烯-苯乙烯共聚物(ABS)复合材料,采用多层叠压法制备了内部Cu粉含量逐渐变化的板状Cu/ABS复合导电梯度功能材料,并对其结构和性能进行了表征。结果表明,所制备导电梯度功能材料的性能与均质复合材料存在很大差异。电性能测试结果显示,随着Cu粉含量沿板材厚度方向的梯度增加,其导电性能发生逾渗转变,体积电阻率从一侧的1016Ω.cm降低到另一侧的105Ω.cm。弯曲性能测试表明,富含ABS树脂的一侧表现出较高的弯曲强度,仅比纯ABS的弯曲强度低6%;而富含填料的另一侧则表现出较高的模量,比纯ABS高约20%。实验证明,将导电复合材料做成梯度结构可以兼顾材料的导电性能和力学性能。     

Transient temperature response in functionally gradient materials

The temperature response in functionally gradient materials (FGM), subjected to pulseor stepwise heating at the front surface, is evaluated. Applicability of the approximate solution for the temperature response is investigated by comparing it with an exact analytical solution for the FGM in which thermophysical properties have certain profiles. When the FGM is composed of conventional solid materials, appropriateness of the approximate solution for the FGM is demonstrated as far as the temperature response near the rear surface is concerned. The approximate solution is also compared with the solution for the multilayered material. It is shown that an eight-layered material can be regarded as an FGM, as far as the temperature response at the rear surface is concerned, and that the approximate solution can predict the temperature response within 6% error. Because of its simplicity and fair degree of agreement, the approximate solution is anticipated to be used not only for qualitative but also for quantitative prediction of the temperature response near the rear surface of the FGM in engineering applications.     

Electromechanical analysis of piezoelectric bimorph actuator in static state considering the nonlinearity at high electric field

This article contains electromechanical analysis of a piezoelectric bimorph actuator at high electric field by incorporating second-order constitutive equations of piezoelectric material. Tip deflection, block force, block moment, block load, output strain energy, output energy density, input electrical energy, and energy efficiency are analytically derived for the actuator at high electric field. The analysis shows that output energy and energy density increase more rapidly at high electric field, compared to the prediction by the linear model. The analysis shows energy efficiency depends on electric field. Some analytical results are validated with the published experimental results.     

压电元件驱动的功能梯度弹性薄板的屈曲

考虑功能梯度薄板,其上下表面嵌有压电执行元件.根据逆压电效应将电压转换成作用于板上的等效电载荷.假设梯度材料的弹性参数为板厚度方向坐标的幂函数,基于经典板理论,导出了功能梯度弹性薄板小挠度屈曲平衡微分方程.利用双三角级数展开法,得到了四边简支具有压电元件的功能梯度矩形板的临界屈曲载荷,在此基础上通过数值例子讨论了弹性板的几何尺寸、材料梯度指数的变化对临界电压(载荷)的影响.研究结果表明,材料的梯度指数对临界电压有重要影响,并且通过调整作用于执行元件上的电压的大小和方向,可实现对结构稳定性的有效控制.     

Estimation of the thermal diffusivity profile in functionally gradient materials with the stepwise heating method

Temperature response in a functionally gradient material (FGM) which is subjected to stepwise heating is investigated, to estimate the profile of the thermal diffusivity from the temperature response at the rear surface of the FGM. Emphasis is placed on a distribution parameter which gives the profiles of the thermophysical properties when an exact analytical solution exists for the temperature response in the FGM. An explicit expression to determine the distribution parameter is obtained as a function of the thermophysical properties at the rear surface. This explicit expression can represent the dependence of the temperature response on the thermophysical properties within 5% in comparison to the exact solution. It is expected that this identification can provide useful insight into the estimation of thermophysical properties in FGMs. The usefulness of this relation is also examined by comparing given and estimated profiles for the thermal diffusivity. Fair agreement is demonstrated as far as the trend and the approximate magnitude are concerned.     

Active control of FGM shells subjected to a temperature gradient via piezoelectric sensor/actuator patches

A generic static and dynamic finite element formulation is derived for the modelling and control of piezoelectric shell laminates under coupled displacement, temperature and electric potential fields. The base shell is of functionally graded material (FGM) type, which consists of combined ceramic–metal materials with different mixing ratios of the ceramic and metal constituents. A multi‐input–multi‐output (MIMO) system is applied to provide active feedback control of the laminated shell using self‐monitoring sensors and self‐controlling actuators through a close loop. Numerical studies clearly show the influence of the positional configurations of sensor/actuator pairs on the effectiveness of static and dynamic control for the shell laminates. The effects of the constituent volume fractions on the static and dynamic responses of the shell laminate are also elucidated. Copyright © 2002 John Wiley & Sons, Ltd.     

碳/碳/Al2O3陶瓷功能梯度材料的制备与研究

从功能梯度材料的原材料的筛选、制备工艺路线的确定出发,对碳/碳/Al2O3陶瓷功能梯度材料的组分分布、微观结构、烧蚀性能及热学性能进行了研究.从试样内表面向外表面,基体碳含量从88%变化到近乎为15%,而Al2O3陶瓷含量从12%变化到85%左右.材料内表面氧-乙炔烧蚀率为0.012nn/s,这表现为碳/碳材料的特性.材料外表面的导热系数达到0.86W/m·K(25℃),表现为良好的隔热效果.     

Multi‐actuated functionally graded piezoelectric micro‐tools design: A multiphysics topology optimization approach

Micro‐tools offer significant promise in a wide range of applications such as cell manipulation, micro‐surgery, and micro/nanotechnology processes. Such special micro‐tools consist of multi‐flexible structures actuated by two or more piezoceramic devices that must generate output displacements and forces at different specified points of the domain and at different directions. The micro‐tool structure acts as a mechanical transformer by amplifying and changing the direction of the piezoceramics output displacements. The design of these micro‐tools involves minimization of the coupling among movements generated by various piezoceramics. To obtain enhanced micro‐tool performance, the concept of multifunctional and functionally graded materials is extended by tailoring elastic and piezoelectric properties of the piezoceramics while simultaneously optimizing the multi‐flexible structural configuration using multiphysics topology optimization. The design process considers the influence of piezoceramic property gradation and also its polarization sign. The method is implemented considering continuum material distribution with special interpolation of fictitious densities in the design domain. As examples, designs of a single piezoactuator, an XY nano‐positioner actuated by two graded piezoceramics, and a micro‐gripper actuated by three graded piezoceramics are considered. The results show that material gradation plays an important role to improve actuator performance, which may also lead to optimal displacements and coupling ratios with reduced amount of piezoelectric material. The present examples are limited to two‐dimensional models because many of the applications for such micro‐tools are planar devices. Copyright © 2008 John Wiley & Sons, Ltd.     

BNT基无铅压电陶瓷的研究与进展--无铅压电陶瓷20年发明专利分析之二

Bi0．5Na0．5TiO3(BNT)基无铅压电陶瓷是目前研究最广泛、最具吸引力的无铅压电陶瓷体系。本文分析了BNT基无铅压电陶瓷近20年的发明专利，着重讨论了相关体系的压电铁电性能，并展望了BNT基压电陶瓷今后的发展趋势。     

压电换能器在并联谐振频率附近特性的研究

对压电换能器在并联谐振频率附近的特性包括功率自动调节性能、品质因数、效率、激励电压及承受电压等进行了分析研究。这些特性对大功率超声换能器的合理运用具有重要影响。用实验验证了分析计算的结果,并在某些方面给出了与串联谐振频率附近特性的比较。