采用旋转涂膜法制备基底生长的定向碳纳米管阵列

 采用化学气相沉积技术,利用旋转涂膜法制备催化剂基底材料,通过对涂膜过程中的角速度、旋转时间以及基底还原过程中温度的控制改变催化剂颗粒的分布状态,获得了粒径均匀分布的催化剂基底,该基底上催化剂颗粒集中分布在47～62 nm区间,再利用该基底生长出定向碳纳米管阵列。运用扫描电镜、透射电镜、拉曼光谱仪对样品进行了表征。结果表明旋转涂膜法制备的基底平整性好于普通的滴膜法,且较其它基底制备方法具有简单易控、可使催化剂均匀分散等特点。利用该基底制备的碳纳米管阵列定向性良好。     

基于SSPCM的新型储能型太阳能蒸馏器实验研究

本文基于定型相变材料(SSPCM)建立了新型储能型太阳能蒸馏器的实验系统,并分别对普通SSPCM和高导热SSPCM的蒸馏特性进行了实验研究.研究发现:与传统太阳能蒸馏器相比,基于普通SSPCM的储能型蒸馏器的日产量提升了 7.5％,采用高导热SSPCM的日产量提升了 39％.此外,本文还对蒸馏器结构进行了优化研究,研制...     

基于红外隐身及多波段兼容隐身材料

随着探测系统的快速发展和探测精度的提高,隐身技术的需求日益迫切.由于传统的红外隐身材料面临着多途径目标探测的严峻挑战,因此开发既能满足红外隐身要求又能满足雷达隐身、可见光隐身、激光隐身要求的新型兼容隐身材料具有重要意义.红外隐身材料主要针对目标的红外辐射特征进行材料、结构设计,降低目标在背景中热红外辐射信号的突出性以及...     

Fabrication and characterization of rod-like nano-hydroxyapatite on MAO coating supported on Mg-Zn-Ca alloy

The poor corrosion resistance of magnesium alloys is a dominant problem that limits their clinical application. In order to solve this challenge, micro-arc oxidation (MAO) was used to fabricate a porous coating on magnesium alloys and then electrochemical deposition (ED) was done to fabricate rod-like nano-hydroxyapatite (RNHA) on MAO coating. The cross-section morphology of the composite coatings and its corresponding energy dispersion spectroscopy (EDS) surficial scanning map of calcium revealed that HA rods were successfully deposited into the pores. The three dimensional morphology and scanning electron microscopy (SEM) image of the composite coatings showed that the distribution of the HA rods was dense and uniform. Atomic force microscope (AFM) observation of the composite coatings showed that the diameters of HA rods varied from 95 nm to 116 nm and the root mean square roughness (RMS) of the composite coatings was about 42 nm, which were favorable for cellular survival. The bonding strength between the HA film and MAO coating increased to 12.3 MPa, almost two times higher than that of the direct electrochemical deposition coating (6.3 MPa). Compared with that of the substrate, the corrosion potential of Mg-Zn-Ca alloy with composite coatings increased by 161 mV and its corrosion current density decreased from 3.36 × 10⁻⁴ A/cm² to 2.40 × 10⁻⁷ A/cm² which was due to the enhancement of bonding strength and the deposition of RNHA in the MAO pores. Immersion tests were carried out at 36.5 ± 0.5 °C in simulated body fluid (SBF). It was found that RNHA can induce the rapid precipitation of calcium orthophosphates in comparison with conventional HA coatings. Thus magnesium alloy coated with the composite coatings is a promising candidate as biodegradable bone implants.     

光学薄膜测量时平顶光束激励的表面热透镜理论模型

推导了调制的平顶光束激励下基于Fresnel衍射积分的表面热透镜理论，通过数值模拟，比较了平顶光束和高斯光束激励下样品内部温度场、表面形变场和探测光衍射信号的径向分布，分析了影响表面热透镜信号的实验参数.结果表明，在最佳探测位置，平顶光束激励下的表面热透镜系统比相同情况下高斯光束激励下的灵敏度高，最高时约2倍，更有利于薄膜吸收测量. 关键词： 表面热透镜 光学薄膜 平顶光束     

粗糙表面涂覆目标的太赫兹波散射特性研究

对具有涂覆层目标的太赫兹波段粗糙表面的散射特性进行了研究. 考虑到表面粗糙度的影响, 可先对反射系数进行修正, 再利用反射系数对等效电磁流进行修正, 得到粗糙涂覆表面的等效电磁流, 然后在物理光学方程的基础上得到粗糙表面涂覆目标的雷达散射截面; 最后进行图形电磁学可视化计算, 并采用Visual C++对模型进行OpenGL显示, 提取像素面元的有效信息对所得理论进行了仿真分析, 研究了不同入射角度、不同频率、不同介质、不同粗糙度和不同涂层厚度下的太赫兹波电磁散射特性, 得到了一些有参考价值的结论.     

Studies on adhesion characteristics and corrosion behaviour of vinyltriethoxysilane/epoxy coating protective system on aluminium

The corrosion stability of vinyltriethoxysilane/epoxy coating protective system on aluminium is strongly related to the strength of bonds forming at the metal/organic coating interface. This article is a study of adhesion, composition, electrochemical and transport properties of epoxy coatings electrodeposited on bare aluminium and aluminium pretreated by vinyltriethoxysilane (VTES) during exposure to 3% NaCl. The VTES film was deposited on aluminium surface from 2% vinyltriethoxysilane solution during 30 s. From the values of adhesion strength (pull-off test), time dependence of pore resistance and coating capacitance of epoxy coating (impedance measurements) and diffusion coefficient of water through epoxy coating (gravimetric liquid sorption measurements), the influence of VTES sublayer on the corrosion stability of the electrodeposited epoxy coating was shown.The work discusses the role of the VTES pretreatment in the enhanced adhesion and corrosion stability of epoxy cataphoretic coating. The electrochemical results showed that the aluminium pretreatment by VTES film improved barrier properties of epoxy coating (greater pore resistance and lower coating capacitance). The lower value of diffusion coefficient of water through epoxy coating indicates the lower porosity, while the smaller adhesion reduction points to better adhesion of epoxy coating on aluminium pretreated by VTES film. The composition of the deposited coatings investigated by XPS enabled the clarification of the bonding mechanism.     

用脉冲紫外激光预处理提高刀具的金刚石涂层的附着强度

采用脉冲紫外激光（XeCl,308nm）表面消融预处理方法以硬质合金为衬底制备了金刚石涂层刀具。利用压痕法对涂层结合强度进行了测试,得到了最佳预处理工艺条件。采用碳化硅增强铝合金材料对制备的金刚石涂层刀具进行了实际切削性能实验。实验结果表明：脉冲紫外激光表面消融预处理方法的采用对刀具的金刚石薄膜涂层附着强度的提高有很大的帮助。     

等离子体结合六甲基二硅胺烷处理提升增透膜抗真空污染性能研究

本文采用溶胶-凝胶法制备了SiO₂增透膜,然后对其进行等离子体结合六甲基二硅胺烷（HMDS）表面改性处理。研究了后处理改性对增透膜表面形貌、微观结构、光学性能及激光损伤性能的影响规律,获得了抗真空有机污染的二氧化硅增透膜。结果表明,增透膜在采用等离子体结合HMDS表面改性处理后,膜层收缩、粗糙度下降、极性羟基等有机基团含量减少;两步后处理改善了增透膜膜层结构和光学性能,显著提高了膜层疏水能力和真空条件下的抗污染性能,并且对溶胶-凝胶二氧化硅增透膜的高损伤阈值属性不产生影响。     

(Sm0.5Gd0.2Nd0.3)2(Hf0.3Ce0.7)2O7复合氧化物的热物理性能

为寻求新型热障涂层用陶瓷材料,本文采用高温固相烧结法制备了(Sm0.5 Gd0.2 Nd0.3)2(Hf0.3 Ce0.7)2 O7复合氧化物.利用XRD分析了其晶体结构,SEM分析其显微组织,膨胀仪测试其热膨胀性能,激光热导仪测试其热扩散系数.结果表明,成功制备了具有单一萤石晶体结构的(Sm0.5 Gd0.2 Nd0...