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排序方式: 共有851条查询结果,搜索用时 46 毫秒
101.
Yong LiuRuiqing Chu Zhijun XuYanjie Zhang Qian ChenGuorong Li 《Materials Science and Engineering: B》2011,176(18):1463-1466
(1−x)(0.948 K0.5Na0.5NbO3-0.052LiSbO3)-xBiAlO3 (KNNLS-xBA) lead-free piezoceramics were synthesized by conventional solid state reaction method. The compositional dependence of phase structure and electrical properties of the ceramics was systemically studied. XRD patterns revealed that all the ceramic samples possessed pure perovskite structure. In addition, polymorphic phase transition (PPT) for the ceramics with BA doping could not be observed in the measuring range from room temperature to 500 °C. Within the studied range of BA addition, the ceramics with x = 0.002 represented a relatively desirable balance between the degradation of the piezoelectric properties, improvement in temperature stability and mechanical quality factor. It was found that the KNNLS-0.002BA ceramics exhibited optimum overall properties (d33 = 233 pC/N, kp = 35%, tanδ = 0.047, Pr = 27.3 μC/cm2, Qm = 56 and Tc = 349 °C), suggesting that this material should be a promising lead-free piezoelectric candidate for piezoelectric applications. 相似文献
102.
Jiang Minhong Deng ManjiaoLu Huaxin Wang ShiLiu Xinyu 《Materials Science and Engineering: B》2011,176(2):167-170
(1 − x) (0.95K0.5Na0.5NbO3-0.05LiSbO3)-xBiScO3 lead-free piezoceramics have been fabricated by an ordinary pressure-less sintering process. The relationship between the BS content, phase structure, density, and piezoelectric properties and their temperature stability was discussed particularly. All compositions show a main perovskite structure, showing room-temperature symmetries of orthorhombic at x = 0, of tetragonal at 0.002 ≤ x ≤ 0.01. When 0.002 ≤ x ≤ 0.008, the ceramics have excellent electrical properties of d33 = 265-305 pC/N, kp = 45-54%, ?r = 1346-1638, Curie temperature Tc = 315-370 °C and depolarizing temperature Td = 315-365 °C, comparable to that of other KNN-based piezoceramics. The results indicate that the ceramics are promising lead-free piezoelectric materials. 相似文献
103.
从符合RoHS指令及无铅产品可靠性方面考虑,EMS企业最好把无铅制程与有铅制程划分区域、分线进行,但由于资金缺少或有铅产品还占有很大市场份额等种种原因,部分中小型EMS企业不得不采用无铅有铅制程共线的方案.在这种复杂的情况下,为防止有铅产品及其材料对无铅产品造成污染,必须要严格对无铅产品生产过程中的各个工序进行有效控制... 相似文献
104.
Relaxor/Ferroelectric Composites: A Solution in the Quest for Practically Viable Lead‐Free Incipient Piezoceramics 下载免费PDF全文
Claudia Groh Daniel J. Franzbach Wook Jo Kyle G. Webber Jens Kling Ljubomira A. Schmitt Hans‐Joachim Kleebe Soon‐Jong Jeong Jae‐Shin Lee Jürgen Rödel 《Advanced functional materials》2014,24(3):356-362
Recently developed lead‐free incipient piezoceramics are promising candidates for off‐resonance actuator applications with their exceptionally large electromechanical strains. Their commercialization currently faces two major challenges: high electric field required for activating the large strains and large strain hysteresis. It is demonstrated that design of a relaxor/ferroelectric composite provides a highly effective way to resolve both challenges. Experimental results in conjunction with numerical simulations provide key parameters for the development of viable incipient piezoceramics. 相似文献
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108.
基于单片机的压电式贾卡控制系统设计 总被引:1,自引:0,他引:1
结合德国Karl Mayer 公司最新研制的贾卡装置及其控制系统,研制了一种基于单片机控制的压电式贾卡控制系统.介绍了该控制系统的总体结构,并且重点阐述了控制系统中控制电路和驱动电路等硬件电路的设计.该系统已通过现场调试.具有工作稳定、效率高、性价比高、维修简单等特点. 相似文献
109.
The tensile behavior and microstructure of bulk, Sn-3.5Ag solders as a function of cooling rate were studied. Cooling rate
is an important processing parameter that affects the microstructure of the solder and, therefore, significantly influences
mechanical behavior. Controlled cooling rates were obtained by cooling specimens in different media: water, air, and furnace.
Cooling rate significantly affected secondary dendrite-arm size and spacing of the Sn-rich phase, as well as the aspect ratio
of Ag3Sn. The Sn-rich dendrite-arm size and spacing were smaller for water-cooled specimens than for air-cooled specimens. Furnace
cooling yielded a nearly eutectic microstructure because the cooling rate approached equilibrium cooling. The morphology of
Ag3Sn also changed from spherical, at a fast cooling rate, to a needlelike morphology for slower cooling. The changes in the
microstructure induced by the cooling rate significantly affected the mechanical behavior of the solder. Yield strength was
found to increase with increasing cooling rate, although ultimate tensile strength and strain-to-failure seemed unaffected
by cooling rate. Cooling rate did not seem to affect Young’s modulus, although a clear coorelation between modulus and porosity
was obtained. The mechanical behavior was correlated with the observed microstructure, and fractographic analysis was employed
to elucidate the underlying damage mechanisms. 相似文献
110.
Ken-Ichi Ohguchi Katsuhiko Sasaki Masahiro Ishibashi 《Journal of Electronic Materials》2006,35(1):132-139
A method to separate plasticity and creep is discussed for a quantitative evaluation of the plastic, transient creep, and
steady-state creep deformations of solder alloys. The method of separation employs an elasto-plastic-creep constitutive model
comprised of the sum of the plastic, transient creep, and steady-state creep deformations. The plastic deformation is expressed
by the Ramberg-Osgood law, the steady-state creep deformation by Garofalo’s creep law, and the transient creep deformation
by a model proposed here. A method to estimate the material constants in the elasto-plastic-creep constitutive model is also
proposed. The method of separation of the various deformations is applied to the deformation of the lead-free solder alloy
Sn/3Ag/0.5Cu and the lead-containing solder alloy Sn/37Pb to compare the differences in the plastic, transient creep, and
steady-state creep deformations. The method of separation provides a powerful tool to select the optimum lead-free solder
alloys for solder joints of electronic devices. 相似文献