激光作用下环氧/硅树脂复合涂层的1.3μm反射特性研究

利用共轭反射计装置,开展了真空环境中激光作用下环氧/硅树脂双层结构复合涂层的1.3μm反射特性研究,测量得到了涂层反射率随样品背表面温度的变化曲线。通过有限元分析和界面热阻修正得到了反射率随涂层温度的变化关系,探讨了反射率随温度的变化机理。研究结果表明,红外连续激光损伤环氧/硅树脂复合涂层,主要表现为底漆热解引发的鼓包分层和面漆热解导致的烧蚀变色;常温下涂层对1.3μm激光的反射率约为0.80,激光辐照初始时变化不明显,鼓包前后出现波动,测量区涂层鼓包、烧蚀后反射率显著下降,最终保持在一个相对较低值;反射率变化与涂层热解过程、损伤方式密切相关,涂层对1.3μm激光的反射率变化存在3个特征温度,分别对应底漆热解、面漆热解和表面状态趋于稳定时的温度。     

基于傅里叶模方法的KDP晶体镀膜减反技术

 采用傅里叶模方法,分析了单点金刚石铣削后KDP晶体表面小尺度波纹的周期和幅值对单层增透膜折射率、厚度以及透射率的影响。研究表明：膜层最佳折射率在1.22左右,在此折射率条件下,保证透射率大于99%的单层增透膜的理想厚度范围应为180~220 nm,并且折射率和膜厚值的选取基本不受晶体表面小尺度波纹周期和幅值的影响。若只考虑SPDT法加工后KDP晶体表面小尺度波纹周期和幅值的实际范围,透射率基本不受波纹周期的影响,但却会随波纹幅值的增大而加速下降。理想镀膜条件下透射率最大值大于99%,并且通常在99.67%~99.94%之间。     

The effect of anti-reflection coating of porous silicon on solar cells efficiency

Anti-reflection coatings of solar cells have been fabricated using different techniques. The techniques used include SiO₂ thermal oxidation, ZnO/TiO₂ sputtering deposition and porous silicon prepared by electrochemical etching. Surface morphology and structural properties of solar cells were investigated by using scanning electron microscopy and atomic forces microscopy. Optical reflectance was obtained by using optical reflectometer. I-V characterizations were studied under 80 mW/cm² illumination conditions. Porous silicon was found to be an excellent anti-reflection coating against incident light when it is compared with another anti-reflection coating and exhibited good light-trapping of a wide wavelength spectrum which produced high efficiency solar cells.     

HL—1装置等离子体辐照Tic涂层实验分析

一、引言在聚变等离子体中控制杂质的污染被认为是获得高温等离子体的重要问题之一。因此对材料要进行优化选择,例如石墨和碳就是目前有利的孔栏材料和结构材料。但是由于碳的自溅射作用和化学活性,在高温溅射时可形成易挥发的碳化物,如甲烷等从而增加了化学腐蚀。某些含碳的化合物如TiC,SiC和BC以及氮化物如TiN和Si_3N_4等是目前研究的一些有用途的材料。实际上TiC或TiN已经用于孔栏,壁内衬涂层或高频加热天线。     

Hydroxyapatite coating on porous silicon substrate obtained by precipitation process

Hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ (HAP) is known as a bioactive and biocompatible material, HAP coatings were used to improve the biocompatible of substrate by many researcher, In this work, HAP thin films on porous silicon (PS) substrates have been prepared by aqueous precipitation method with rapid thermal annealing (RTA) processes. The HAP films had been prepared under the annealing temperature ranging from 300 to 1000 °C. By the measurement of X-ray diffraction (XRD), it was found that for the crystallinity optimization, the heat-treatment at 850–950 °C for 1 h would be favorable. Atomic force microscopy (AFM) and scanning electron microscope (SEM) measurements reveal a dense and smooth surface of the HAP film, and tightly adherence of the coating on porous silicon substrate after sintered. Thus, by this method, porous silicon could be increased its bioactivity and so that could be used in the biomedical area.     

提高光纤F-P应变传感器输出信号质量的方法研究

光纤F-P应变传感器输出信号质量的好坏直接影响解调精度.从光纤F-P应变传感器的基本原理出发,针对光纤F-P腔内损耗的问题,提出了用增加端面反射率的办法来弥补耦合损耗的影响;并通过理论分析、计算机仿真和实验对该问题进行了研究.实验表明,选用与F-P腔固有的最佳反射率匹配的端面镀膜,对增加干涉图样的对比度,提高信号输出幅值有很好的效果.     

塑料光纤相位调制灵敏度的研究

研究了压电涂层PMMA纤芯塑料光纤中的相位调制.射频信号通过对光纤外层的压电涂层作用,使纤芯中产生应变,从而对光纤中的光信号进行相位调制.数值计算结果表明,与传统的石英光纤相比,PMMA塑料光纤的相位调制的灵敏度要高数十倍以上.     

Particle size dependence of relaxivity for silica-coated iron oxide nanoparticles

We investigate the particle size dependence of the relaxivity of hydrogen protons in an aqueous solution of iron oxide (Fe₃O₄) nanoparticles coated in silica for biocompatibility. The T₁ and T₂ relaxation times for various concentrations of silica-coated nanoparticles were determined by a magnetic resonance scanner. We find that the relaxivity increased linearly with increasing particle size. The T₂ relaxivity (R₂) is more than 50 times larger than the T₁ relaxivity (R₁) for the nanoparticle contrast agent, which reflects the fact that the T₂ relaxation is mainly influenced by outer sphere processes. The high R₂/R₁ ratio demonstrates that silica-coated iron oxide nanoparticles may serve as a T₂ contrast agents in magnetic resonance imaging with high efficacy.     

Laser surface alloying of an electroless Ni–P coating with Al-356 substrate

Laser surface alloying of an electroless plating Ni–P coatings on an Al-356 aluminium alloy was carried out using a 1-kW pulsed Nd:YAG laser. The microstructure, chemical composition and phase identification of the alloyed layer were determined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD), respectively. It was shown that laser surface treatment produced a relatively smooth, crack-free and hard surface layer. The hardness of the surface significantly increased due to the formation of the uniformly distributed fine Ni–Al intermetallic phases. The corrosion behaviour of the surface alloyed specimens in 3.5% NaCl solution at 23 °C was also determined by electrochemical techniques. The laser-alloyed surface showed an improved corrosion and pitting potential compared to the substrate as well as the plated Ni–P coating.     

相对论速调管放大器杂模振荡的抑制

研究了相对论速调管放大器（RKA）输入腔和中间腔之间的高阶杂模振荡问题。通过模式分析得知杂模在谐振腔内为TM11模式,而在漂移管中表现为TE11模式,针对该模式能在漂移管中传输的特性,利用漂移管内壁涂覆吸波材料吸收杂模功率的方法进行抑制。通过3维粒子模拟程序,分析了吸波材料的电导率及涂覆长度对抑制杂模增长率的影响。利用模拟分析得到的结果,对漂移管中涂覆吸波材料的RKA输入腔及中间腔结构进行了3维模拟研究,结果显示:合适的吸波材料的引入能够很好地抑制RKA输入腔和中间腔之间的杂模振荡。