湿度对FEP，PTFE，PCTFE和PI驻极体电荷稳定性的影响

本文通过等温表面电位衰减曲线和开路TSD测量，研究了环境湿度对4种典型驻极本材料FEP，PTFE，PCTFE和PI柱极体的电荷贮存稳定性及脱阱电荷体内输运的影响，利用热脉技术讨论了不同环境湿度下平均电荷重心的迁移规律，研究结果指出：FEP，PTFE，PCTFE和PI驻极体的电荷贮存寿命明显地受贮存环境湿度的影响，湿度越高，电荷衰减越快，上述驻极体材料的平均电荷重心随注极时相对温度的增加而向样品体内迁移，湿度越高，迁移越明显。     

PBLZT弛豫铁电陶瓷的动态及偏压介电和压电特性

测量了３ｍｏｌ％Ｂａ掺杂的ＰＬＺＴ１０／６５／３５弛豫铁电陶瓷的电滞回线、横向场诱应变、偏压下的介电常数和压电常数,并根据电滞回线和场诱应变曲线的斜率计算了动态介电常数和压电常数．实验表明,电场＜８ｋＶ／ｃｍ时,动态介电常数比偏压介电常数大很多,电场＞８ｋＶ／ｃｍ时,差值随电场增大而减小;电场在３～１５ｋＶ／ｃｍ之间时,动态压电常数比偏压压电常数大很多,电场＜３ｋＶ／ｃｍ及＞１５ｋＶ／ｃｍ时,动态压电常数和偏压压电常数相差不大．     

Piezoelectricity and polarization studies in unstretched san copolymer films

The piezoelectricity and charge storage in unstretched corona poled poly (styrene-co-acrylonitrile) films have been investigated under different poling conditions. The piezoelectric coefficient d₃₁ has been measured as a function of poling field (E_p) and poling temperature (T_p) and the maximum value of d₃₁ 1.0 pC/N has been obtained at E_p 46 MV/m and T_p = 85 °C. The Frolich equation for dipolar polarization has been applied for quantitative analysis of the thermally stimulated current (TSC). The g-factor = 1.7 has been obtained, suggesting cooperative dipolar relaxation. The Young's modulus has been measured to be 0.45 GPa. The dipolar polarization from the TSC and the elastic modulus of the films have been correlated to the piezoelectricity through the modified equation for d₃₁ for amorphous SAN films. It has been concluded that the mechanisms of the dimensional and the local field effects are involved in the piezoelectric phenomenon.     

碳化硼-有机硅二维层状复合材料的制备与动态力学性能

科技发展对材料性能提出越来越高的要求,通过对材料内部结构进行有序排列使其在特定方向上实现性能最佳发挥是目前解决高性能应用需求的一个有效的方法.传统单向冷冻技术无法实现二维有序结构的制备.通过双向冷冻方法制备了厘米级的单取向碳化硼(B4C)层状结构支架,在其层间填充聚二甲基硅氧烷(PDMS)制备出具有各向异性的碳化硼-有...     

Micromagnetics of laminated Permalloy films

The edge curling wall (ECW) is observed in an optical Kerr microscope. Conditions are derived energetically favoring single transverse domains with ECWs over other multiple closure domains or single longitudinal domains that are undesirable because of their low permeability. Computed figures illustrate how the maximum permissible spacer thickness depends on Permalloy sublayer thickness, uniaxial anisotropy, width of the magnetic strip, mismatch of Permalloy thickness, and perpendicular anisotropy. The case with strip width W=100 mu m and vanishing magnetostriction or stress should require only a few sublayers. However, if W is very small, or if stress-induced or some other form of perpendicular anisotropy is excessive, then attainment of single transversely magnetized domains requires many sublayers. Some of these conclusions are supported by microscopic observations.<>     

Nonlinear dynamic behavior of a piezothermoelastic laminated plate with anisotropic material properties

Summary. In this paper, we analyze the nonlinear dynamic behavior of a piezothermoelastic laminated plate with anisotropic material properties. The analytical model is a rectangular laminate composed of fiber-reinforced laminae and piezoelectric layers. The model is assumed to be a symmetric cross-ply laminate with all egdes simply-supported and to be subjected to mechanical, thermal and electrical loads as intended control procedures or as disturbances. The von Kármán strains are introduced to treat non-linear deformation. The behavior of the laminate is analyzed by using the Galerkin Method. We discuss the following quantities: (i) the buckling temperature due to in-plane thermal load; (ii) the large static deflection due to combined in-plane and anti-plane loads; (iii) the natural frequency of infinitesimal oscillation around the static equilibrium state; (iv) the natural frequency of the oscillation with finite amplitude around the static equilibrium state. Moreover, numerical examples are shown to investigate the methods to rise the buckling temperature, to linearize the thermal deflection and the natural frequencies by applying the electrical voltage to the piezoelectric actuators.     

Thermal dynamic stability of parametrically excited laminated composite plates with temperature-dependent properties

Thermal dynamic stability analysis is performed on periodically-loaded laminated composite plates with temperature-dependent properties. The periodic load is taken to be a combination of periodic axial and bending stress. A set of differential equations of Mathieu–Hill type is formed to determine the dynamic instability regions based on Bolotin's method. The thermal dynamic instability of laminate plates with respective temperature-dependent and temperature-independent properties is examined. The effects of various parameters on the instability region and dynamic instability index are also discussed. The results show that the temperature-dependent properties have a significant influence on the thermal dynamic behavior of laminated plates.     

多孔PTFE/FEP复合驻极体膜的压电性研究

本文报道采用高温熔融粘合工艺和电晕注极方法制备了由多孔PTFE/FEP复合而成的空间电荷驻极体压电膜.根据Kacprzyk等人提出的复合驻极体膜的压电模型,结合等温表面电位衰减和压电系数衰减测量结果,研究了制备工艺对复合膜压电活性的影响.结果表明压电效应的大小不仅取决于捕获在材料中电荷密度的大小,还与被捕获电荷在材料中的存在形式和分布有关.     

包装复合薄膜渗透性的模拟分析

分析了食品包装薄膜透气性的测试方法和气体渗透性,并从单层包装材料的渗透性理论导出层合包装材料的渗透系数表达式,并设计了一个计算层合包装材料渗透系数的应用程序,并用单层材料的渗透性数据计算层合包装材料的渗透系数.     

Study on the dynamic resistance switching properties of NiO thin films

The resistive switching properties of NiO-based memory cells were investigated utilizing test structures with a storage contact size of 150 nm in diameter. Two well defined stable resistance states with high OFF/ON ratios were achieved by unipolar operation. Detailed electrical characterizations with respect to nonvolatile memory applications reveal fast (< 300 ns) and reliable switching performance at low operating voltages (< 2.5 V). Promising results of endurance data (> 1000 cycles) and retention tests up to 110 °C show excellent stability and indicate the competitive potential with respect to established nonvolatile memory devices.     

Characteristics of laminated alloy films heads for high frequencyrecording

Excellent performance of laminated Fe-Si-Al alloy film heads is demonstrated in applications to high-definition VCR and to digital recording. It is emphasized that these results are derived not only from the ring-shaped core geometry but also from the isotropic behavior in the magnetic properties of the sputtered Fe-Si-Al alloy films. The experimental results on the isotropic magnetic behavior are summarized. A mass-production process for the laminated alloy film heads is introduced, emphasizing the importance of stacked bar fabrication steps     

双组分复合薄膜用水性聚氨酯胶粘剂的研究

研究了双组分复合薄膜用水性聚氨酯胶粘剂中水性多异氰酸酯固化剂对复合薄膜T剥离强度、胶膜的吸水率、接触角的影响.结果表明:随着固化剂用量的增大,复合薄膜T剥离强度呈现出先增大后减小的变化趋势,熟化时间和熟化温度也影响复合薄膜的T剥离强度;此外,胶膜的吸水率随着固化剂用量增加呈上升趋势,而接触角呈下降趋势.