射流侵彻陶瓷力学特性实验研究

 利用闪光X射线摄影技术观察了射流在氧化铝陶瓷靶中的侵彻过程。结果表明，射流在侵彻氧化铝陶瓷过程中，侵彻通道发生了一定程度的倒塌现象，致使后续射流断裂，部分断裂粒子扭曲、偏离侵彻方向，降低了射流侵彻能力。     

基于PEG凝集的压电免疫传感器用于日本血吸虫抗体的测定

以ＰＥＧ为乳剂，建立了一种新的液相压电免疫分析法，并用于日本血吸虫感染兔血清的测定。初步探讨了这种ＰＥＧ液相压电免疫传顺的响应机理，详细考察了ＰＥＧ浓度，ＰＥＧ－ＡＷＡ复合时间及测试温度等因素对频移的影响，对５个兔血样的测试结果表明，应用该方法不仅对日本血吸虫的阳性判别率可达１００％，而且能定量测定感染血清中血吸虫抗体的含量。     

Estimation of frequency characteristics of the Tonpilz piezoelectric transducer with a bending piezoelectric disk

A Tonpilz piezoelectric transducer which has a bending piezoelectric disk on the radiation surface for widening the frequency band to improve sonar detection performance in shallow water has been proposed. Variance of transmitting voltage response of this transducer depend on the phase difference between signals which applies to the ring-stack and the bending-disk piezoelectric resonators. Thus, an estimation of an optimal phase difference, which can be applied for obtaining the maximum value of transmitting voltage response, is important factor to assemble sonar array with sonar transducers. In this paper, we applied three methods to estimate transmitting voltage response at an arbitrary phase difference from a few measurements, and the estimation errors of those methods affected by internal impedances of power sources and/or noise are investigated to select the best method. The effectiveness of the best method was verified by water-pool experiments.     

The effect of filler on the temperature coefficient of the relative permittivity of PTFE/ceramic composites

High permittivity and low-loss ceramic fillers have been prepared by means of the solid state ceramic route. Ceramic-filled composites were prepared by the Sigma Mixing, Extrusion, Calendering, which was followed by the Hot pressing (SMECH) process. The microwave dielectric properties of the composites were studied using X-band waveguide cavity perturbation technique. The temperature coefficient of the relative permittivity of the composites was investigated in the 0-100 °C temperature range using a hot and cold chamber coupled with an impedance analyzer. The temperature coefficient of the relative permittivity of the composites showed strong dependence on the temperature coefficient of the relative permittivity of the filler material. In the present study, a high-permittivity polymer/ceramic composite, having τ_εr ∼63 ppm/K, has been realized. This composite is suitable for outdoor wireless applications.     

基于压电探测判定激光支持燃烧波和爆轰波的点燃阈值

为了获得激光支持燃烧波和爆轰波的点燃阈值,采用压电探测器检测波长为1 064nm的Nd:YAG激光作用在铝靶表面所产生的应变和冲压。从实验结果观察到压电信号的变化分为3个阶段,分别为光热弹性应变阶段、等离子体增强耦合阶段和激光支持爆轰波对靶表面的压力阶段,并从理论上研究了这3个阶段的激光与靶材料相互作用的机理,从而可以从压电信号是否发生跃变判断出激光支持燃烧波和激光支持爆轰波的点燃阈值,与其它方法所得到结果基本吻合。     

X-ray fluorescence (conventional and 3D) and scanning electron microscopy for the investigation of Portuguese polychrome glazed ceramics: Advances in the knowledge of the manufacturing techniques

This work shows the first analytical results obtained by X-Ray Fluorescence (XRF) (conventional and 3D) and Scanning Electron Microscopy with Energy Dispersive System (SEM-EDS) on original Portuguese ceramic pieces produced between the 16th and 18th centuries in Coimbra and Lisbon. Experts distinguished these productions based only on the color, texture and brightness, which originates mislabeling in some cases.Thanks to lateral and spatial resolution in the micrometer regime, the results obtained with μ-XRF were essential in determining the glaze and pigment thicknesses by monitoring the profile of the most abundant element in each “layer”. Furthermore, the dissemination of these elements throughout the glaze is different depending on the glaze composition, firing temperature and on the pigment itself. Hence, the crucial point of this investigation was to analyze and understand the interfaces color/glaze and glaze/ceramic support.Together with the XRF results, images captured by SEM and the corresponding semi-quantitative EDS data revealed different manufacturing processes used by the two production centers. Different capture modes were suitable to distinguish different crystals from the minerals that confer the color of the pigments used and to enhance the fact that some of them are very well spread through the glassy matrix, sustaining the theory of an evolved and careful procedure in the manufacturing process of the glaze.     

670nm电光调Q陶瓷激光器

为了进一步研究Nd∶YAG陶瓷激光器的红光波段,研制了一台重复频率为1 000 Hz的670 nm电光调Q Nd∶YAG陶瓷激光器.采用三个激光二极管列阵侧面抽运掺杂浓度为1.1at%、尺寸为Φ3×50 mm2的Nd∶YAG陶瓷晶体,根据实验测量的陶瓷晶体热透镜焦距,优化设计了折叠腔的各个参量,并对陶瓷晶体及倍频晶体热...     

内窥式二维光纤扫描探头及其驱动方法

基于压电换能器技术设计了一种应用于光学相干层析成像的新型内窥式二维光纤扫描探头,即利用两片压电陶瓷片和一片薄导电基片驱动光纤探头.该探头利用光纤悬臂的共振特性,通过对压电陶瓷施加等于光纤共振频率的混频信号,能同时激发光纤悬臂两正交方向上的振动,可以实现光纤悬臂的二维扫描.建立了理论模型并进行了有限元仿真分析,最后搭建了...     

Dielectric and piezoelectric properties of manganese‐modified PbHfO3–PbTiO3–Pb(Mg1/3Nb2/3)O3 ternary ceramics with morphotropic phase boundary compositions

High piezoelectric and electromechanical properties were reported in the PbHfO₃–PbTiO₃–Pb(Mg_1/3Nb_2/3)O₃ ternary system with morphotropic phase boundary (MPB) compositions. This work focuses on the effect of MnO₂ addition on 0.8Pb(Hf_0.443Ti_0.557)O₃–0.2PMN (0.8PHT–0.2PMN) ceramics. It was observed that the Mn acceptor modification induced a “hardening” effect in 0.8PHT–0.2PMN, with decreased piezoelectric coefficients d₃₃ and dielectric loss tan δ and a significantly increased mechanical quality factor Q_m. Moreover, the 0.2 wt% MnO₂‐doped 0.8PHT–0.2PMN ceramics exhibited good piezoelectric and electromechanical properties with d₃₃, planar electromechanical coupling k_p and Q_m being on the order of 360 pC/N, 61% and 700, respectively, showing advantages compared to those of commercial hard PZT4 ceramics, which is attractive for high power applications. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)