基于微流变法的铬冻胶体系动态成胶过程测定

针对部分水解聚丙烯酰胺(HPAM)与氯化铬(CrCl_3)的交联体系,采用光学微流变仪,以宏观黏度因子(MVI)和弹性因子(EI)为评价指标,研究了在不同交联剂浓度、pH值、盐浓度、温度条件下体系动态成胶的微流变特征。结果表明,随着交联剂质量分数增大、温度升高、初冻时间缩短、MVI值和EI值增大,冻胶强度增加;pH=7时的冻胶最稳定,弱碱性环境下,体系的MVI值和EI值减小,成冻时间延长且冻胶强度降低;弱酸性条件下,初冻时间缩短,但体系易破胶;随着NaCl浓度的升高,MVI值和EI值减小,初冻时间缩短冻胶强度降低。此结果与常规评价方法对比表明两者具有一致性。此外,通过对体系微观结构的表征,初步建立了一种原位测定铬冻胶体系动态成胶的微流变方法。     

掺杂对Al_2O_3/TiAl复合材料性能的影响

本研究采用Ti-Al-TiO2-La2O3体系,通过热压烧结工艺原位合成了Al2O3/TiAl复合材料.借助X射线衍射(XRD)、扫描电镜(SEM)等分析研究了材料的物相组成和微观组织结构,同时分别将掺杂La2O3和掺杂Fe2O3对合成Al2O3/TiAl复合材料微观结构和力学性能的影响进行了对比.结果表明:掺杂La2O3合成的Al2O3/TiAl复合材料基体尺寸相对掺杂Fe2O3合成产物较小,分散更加均匀,致密度更高.当La2O3掺杂量为3.93wt%时,Al2O3/TiAl复合材料的抗弯强度和断裂韧性达到最大值,分别为701.95MPa和7.79MPa·m1/2.由于稀土氧化物具有对基体和增强颗粒的净化,细化晶粒等作用,因此提高了TiAl基体与Al2O3增强颗粒结合强度,所以掺杂La2O3合成材料的力学性能相比掺杂Fe2O3合成的产物较高.     

纳米Si薄膜的结构及压阻效应

使用ＨＲＥＭ及ＳＴＭ技术检测了纳米Ｓｉ薄膜的微结构，纳米Ｓｉ薄膜由大量的细微Ｓｉ晶粒以及大量的晶粒间界面区组成，这一特殊的结构造成纳米Ｓｉ薄膜具有较大的压阻效应及较高氢含量，本文分析讨论了薄膜微结构对其压阻效应的作用，并认为纳米Ｓｉ薄膜材料将是一种理想的传感器材料。     

Solution heat treatment of 319 aluminium alloy containing ~0.5 wt% Mg. Part 2—microstructure and fractography

In Part 1 of this work, the tensile properties of 319 aluminium alloy obtained following several single-stage and two-stage solution treatments were discussed. In the present part, the microstructural changes associated with these treatments have been analysed. The results show that the addition of Mg in quantities up to 0.5 wt% leads to a significant increase in the volume fraction of Cu-containing phases with a clear tendency to segregation in localized areas. Strontium in amounts of ~250 ppm improves the shape and distribution of the eutectic silicon particles in the as-cast condition. However, it also results in greater segregation of the Cu phases to areas free of Si particles. Two types of defects occur during solution heat treatment of the 319 alloy test bars: “dark spots” with no distinct boundaries with the surrounding matrix that appear when the test bars are heat treated at temperatures close to 520°C regardless of the Mg level of the alloy, and “burn spots” that arise from the burning of the molten phases in alloy test bars containing a high Mg level when the test bars are solution heat treated at a temperature higher than 520°C. The increase in strain fracture, enhanced by a reduction in the amount of intermetallics, results in a longer deformation zone beneath the rupture surface.     

独角仙鞘翅微结构及其纳米力学性能

利用SEM对独角仙鞘翅的微结构进行了观测, 并借助纳米压痕仪测试分析了鞘翅的纳米力学性能。SEM试验表明独角仙鞘翅是一种具有拱形空腔的中空轻质生物复合材料, 其断面占空比为26.36%。鞘翅由外表皮和内表皮构成, 而内表皮又通过11~12层纤维层采用45°角正交叠加铺设, 层间辅以许多微纤维丝交叉连接方式编织在一起, 形成层合板结构。试验测得鞘翅外表皮纳米力学性能分别为: 硬度(0.28±0.13) GPa, 弹性模量(5.62±1.21) GPa, 接触刚度 (1.67±0.14)×10⁴ N/m。其纳米力学性能呈现拓扑分布规律, 由头部至尾部区域有增大趋势。试验测试结果为后续研究中设计一种基于独角仙鞘翅的新型轻质仿生结构提供了仿生学模型和理论参考。     

泡沫泥浆泥饼的特性研究

对泡沫泥浆泥饼进行了大量微观结构分析，揭示出泡沫泥饼具有粘弹性、疏水性等特性，对泡沫泥浆防塌护壁机理进行了论证。     

超声振动辅助加工表面微结构及其特性研究进展

针对超声振动复合加工方法种类繁多且表面微结构指征复杂等问题,阐述了表面微结构的内容和研究现状,论述了国内外超声切削、磨削、表面强化等方法的加工原理及超声振动加工表面微结构特性的试验研究方法,归纳了超声振动条件下表面粗糙度、表面微观形貌的建模方法及其特点,讨论了实验回归建模、数值解析建模和神经网络建模的研究进展,并预测了国内外超声振动表面加工的新技术领域和发展方向,对改善高性能难加工材料的表面微结构特性具有重要意义。     

电致发光器件衬底透镜微结构纳米热压印制备的研究

采用纳米压印技术在OLED器件衬底上制备可传递三维立体透镜微结构,可有效减小波导、增加出光耦合,从而有望增加器件出光效率。采用紫外曝光与湿法腐蚀技术相结合的方法来制备高精度的石英玻璃纳米压印模板,对模板进行清洗与抗黏连处理。结果表明：所形成的透镜微结构具有平整度好、压印精度高的特点;此种方法制备微结构工艺简单易行,可大面积实现,工艺可操作性、重复性好。     

不同粒径膨胀石墨的制备及其微观结构

对化学法制备膨胀石墨的工艺条件的选择进行了分析,以硝酸与磷酸的混酸为插层剂、高锰酸钾为氧化剂制备出了不同粒径的膨胀石墨,利用正交实验和平行实验确定了最佳工艺条件;研究了石墨粒度效应对氧化剂用量的影响;并对不同粒径膨胀石墨的微观结构进行了研究。研究结果表明,制备大鳞片膨胀石墨的最佳工艺为：石墨与混酸的质量体积比为1：4,...     

Electron transportation and optical properties of microstructure TiO2 films: applied in dye-sensitized solar cells

Micro-structure of TiO2 films in dye-sensitized solar cells (DSSCs) can affect light absorption and electron transportation that impact on the characteristics of currentvoltage (J-V). In this paper, films with different surface area, pore size and porosity were obtained by adding different ratio of ethyl cellulose (Ec-S) to pastes, and a photo-electric conversion efficiency (η) of 7.55% with a showed that film with this optimum ratio had the most suitable pore size and surface area for good properties of photovoltaic, which had a low reflectivity and high transmission rate, and the efficiency of light utilization was improved. Moreover, measurements by intensitymodulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS)implied that the electron transport time (rd) increased as the content of Ec-S increased, which was related to the larger surface area. Results of steady-state cyclic voltammetry indicated that diffusion-limited current density (Jlim) of I3-;in TiO2 film increased with its porosity, which revealed that the transportation ofredox mediators in the electrolyte was speeded up.