入射角和极化方式对吸波材料反射率的影响计算

分析了角锥型吸波材料在暗室中的应用特点,论述了现有的角锥材料仿真计算方法的原理及其应用局限性,介绍了一种根据垂直入射的反射率测试值所确立的角锥材料简化计算模型一平板近似法;根据该计算模型,文章给出了吸波材料在不同入射角、不同极化方式下的反射率计算公式。分析比较了平板近似法、均匀化模型法以及矩量法对角锥材料垂直入射反射率的计算结果;并以600mm高角锥材料为例,计算了不同入射角和极化方式对角锥材料反射率的影响。这种方法对于相关工程设计人员进行角锥型吸波材料和电波暗室的仿真计算具有参考意义。     

原位一步法制备表面银化的聚酰亚胺纳米复合薄膜

介绍了原位一步自金属化制备银/聚酰亚胺(PI)纳米复合薄膜的方法。以银盐为线索,评述了各种银盐/二酐/二胺体系所制得的复合薄膜的性能。采用该法可制得具有较高的表面反射率和电导率,优异的界面粘结性,并保持母体PI大部分优异性能的复合薄膜;其反射性和导电性与银含量,银的配位体或者反离子,二酐、二胺的种类及热处理工艺等因素相关。使用三氟乙酰丙酮银盐(AgTFA),银的质量分数为12％以上,进行适当的热处理,则某些体系所制薄膜的表面反射性和导电性可以达到纯银的水平,而其他的银盐体系制备的薄膜只能达到中等反射性而无导电性,但对薄膜表面进行轻微抛光可以提高反射性和导电性。     

Crystal structure,chemical bonding and infrared reflectivity of microwave dielectric SrIn2O4 ceramics

In this work, the orthorhombic structured SrIn₂O₄ ceramics with a space group Pnam were synthesized by a solid-state reaction method. A high relative density (96.5%) coupled with excellent microwave dielectric properties (ε_r ∼ 12.3, Q × f = 96,900 GHz, τ_f ∼ −61.6 ppm/°C) were obtained as sintered 1300 °C for 4 h. The bond valence analysis demonstrates that the large sized cation Sr²⁺ exhibits a compressed state, while the In³⁺ exhibits a weaken rattling effect. The P-V-L chemical bond theory analysis indicates that the In-O bonds play a key role in affecting the dielectric loss. The thermally conductivity activation energy E_dc (0.94 eV) of SrIn₂O₄ was obtained by the dielectric spectroscopy, indicating that the E_dc was contributed to the double ionized oxygen vacancies. Furthermore, the intrinsic dielectric properties (ε_r ∼ 11.2, Q × f = 148,900 GHz) of SrIn₂O₄ were obtained by infrared reflectivity spectroscopy.     

Cold sintered temperature stable xLi2MoO4-(1-x)(LiBi)0.5MoO4 microwave dielectric ceramics

Temperature stable xLi₂MoO₄-(1-x)(LiBi)_0.5MoO₄ (x = 0, 40, 50, 60, 70, 100 vol%) microwave dielectric ceramics obtained by cold sintering process (CSP) under a mild sintering condition (120 ℃/30 min/200 MPa) are introduced in this work. The XRD, SEM, and Raman analysis indicate the coexistence of Li₂MoO₄ and (LiBi)_0.5MoO₄ phases. Li₂MoO₄-(LiBi)_0.5MoO₄ ceramics are compatible with Ag and Al electrode materials under cold sintering condition. The specimens exhibit high relative densities and good microwave dielectric properties (relative permittivities: 31.5–5.5; Q×f values: 1900 - 18,500 GHz; TCF values: from +144 ppm/℃ to ?106 ppm/℃), in particular, TCF = +0.7 ppm/℃ can be obtained in the case of x = 50 vol%. The extrapolated microwave dielectric properties obtained by the fitted infrared reflectivity spectrum are close to the measured data, revealing that the dielectric responses of cold sintered Li₂MoO₄-(LiBi)_0.5MoO₄ ceramics in the microwave range are dominated by the polar optical phonons.     

基于光纤反射率特性的温度传感研究

利用光纤折射率随温度变化的特性, 研究了光纤温度传感系统的性能。采用窄线宽激光器和具有脉冲调制功能的半导体放大器(SOA) 产生周期变化方波光脉冲信号, 该方波信号依次经过掺饵光纤放大器(EDFA)、光纤环形器和长度为2 km 的传感光纤后反射至光电探测器(PD) 处。对置于水浴锅中的部分传感光纤进行加热, 则光反射的信号幅度会随温度变化发生改变。选用调制频率为10 kHz, 幅度为(峰峰值) 10 V, 占空比为1% 的方波代替传统的正弦信号, 通过测量2847 ℃ (28、33、38、42、47 ℃) 温度范围内反射光的改变, 得到该温度传感系统的灵敏度为3.888 mV/℃, 一次拟合度可达0.905 0, 二次拟合度可达0.970 8, 验证得到该系统具有较好的拟合度。     

Specular X-ray reflectivity analysis of adhesion interface-dependent density profiles in nanometer-scale siloxane-based liquid films

Nanometer-scale thick liquid films of poly(methylhydro-dimethyl)siloxane copolymer (PMDMS) deposited on hydrophilic and hydrophobic solid organic films have been studied using synchrotron X-ray specular reflectivity (XRR). The physico-chemical properties of liquid PMDMS at the interfacial level are controlled by the nature of the solid surface. Detailed analysis of the XRR-data revealed the formation of a low-density region in the liquid PMDMS film in the vicinity of the hydrophobic surface, whereas a densely packed molecular layer is formed at the liquid PMDMS-hydrophilic substrate interface. Non-covalent polymer chains are ‘frozen’ at the solid-liquid interfaces in the confined liquid films and interactions with the substrate surfaces (i.e. hydrogen bonding) are responsible for distinctly different density profiles.     

高反射激光泵浦腔材料的研制

本研究制备了氧化铝陶瓷泵浦腔，并在其表面施上了掺杂具有激活和敏化作用的稀土元素的釉，以提高腔体釉面的反射率。试验中对只掺杂激活离子和掺杂了敏化离子及激活离子的样品的反射性进行了对比研究，发现掺杂稀土元素的釉能有效地提高氧化铝陶瓷的白度及反射率。     

新型水性高反射高辐射隔热涂料的制备及性能研究

在传统水性涂料配方的基础上加入高反射率的玻化微珠和超细二氧化钛组成的复合颜填料及红外辐射型复合功能填料,实现高反射和高辐射作用,制得高反射和高辐射为主,传统隔热为辅的新型水性隔热涂料,达到最佳的隔热保温效果。     

单一炼焦煤煤岩性质对黏结性和结焦性的影响

对不同变质程度单种煤的煤岩性质以及对应的40kg试验焦炉所炼焦炭的性质进行测定和分析表明,单种煤的黏结性不仅受煤变质程度影响,而且受炼焦煤中煤岩组成的影响,单种煤的镜质组平均最大反射率在1.1%左右时,煤的黏结性最好;镜质组反射率分布在1.1%~1.3%所占比例为30%左右时,所得焦炭的M40和M10最好。     

中煤级煤甲烷饱和吸附量的数值模拟计算

根据表征中煤级煤（镜质组最大反射率R_o,max=0.65%～2.50%）的系列等温吸附（20℃、30℃、40℃和50℃这4个实测温度）“煤变质程度-压力-吸附量”的三变量数学方程,建立一组“煤变质程度-温度-压力-吸附量”这4个共同存在并相互影响的四变量数学方程。该四变量数学方程用于预测1200m以浅的中煤级煤甲烷饱和吸附量。这种数学转换的平均相对误差在7.28%～9.49%之间。有处理中煤级煤甲烷饱和吸附量的数值模拟的软件著作。只要将5个实测数据：镜质组最大反射率R_0,max、温度梯度、压力梯度、埋深和恒温层温度,输入相应可编辑文本框中,就可以输出5个值：饱和吸附量V、温度-压力-吸附量方程中的参数（A、B、Δ、β）。还可以输出在自己感兴趣的镜质组最大反射率R_0,max、温度梯度、压力梯度、埋深和恒温层温度下,“R_0,max值时温压吸附曲面”和“吸附量随埋深变化图”。