Alginate fibres containing discrete liquid filled vacuoles for controlled delivery of healing agents in fibre reinforced composites

The work addressed involves the preparation and application of a compartmented polymer fibre, containing multiple separated domains with liquid agent for controlled release. The created fibre is a design for improvement to the existing liquid encapsulated self-healing systems such as fibre reinforced composites, i.e. increasing the released volume per intersection and maintaining self-repairing functionality. Additionally, we have focused on optimization of the fibre mechanical properties and control over liquid vacuole morphology.     

Preparation of bulk β-FeSi2 by synthetical control of melt cyclical superheating,solidification and cooling process

A new method of melt cyclical superheating combined with the control of solidification and cooling process as well as appropriate heat treatment was proposed to prepare bulk β-FeSi₂. FeSi₂ precursor of φ18 × 17 mm in size was obtained under the conditions of melt superheating temperature 1550 °C, superheating time 10 min, recycling times 3, solidification rate 30 °C/s, cooling rate 12 °C/min from solidification temperature to 700 °C and cooling naturally from 700 °C to room temperature. The precursor had homogeneous and complete α + ε eutectic structure, with the rod-like ε phase of 1–2 μm in diameter. After the precursor with complete α + ε eutectic structure were annealed at 900 °C for 150 h, both the α and ε phases totally disappeared and were transformed into β-FeSi₂ except few residual Si-rich phase.     

Coprecipitation synthesis of hollow Zn2SnO4 spheres

Pure and Dy³⁺-doped Zn₂SnO₄ (ZTO) hollow spheres, integrated with nanoparticles, have been synthesized using the coprecipitation method. The ZTO spheres have been characterized with X-ray diffraction and scanning electron microscope. The photoluminescence and photocatalytic properties are investigated. The influences of Dy³⁺ ions on the morphology and the photoluminescence of ZTO have been explained in detail.     

Hierarchical heterostructure of porous NiO nanosheets on flower-like ZnO assembled by hexagonal nanorods for high-performance gas sensor

A novel hierarchical heterostructure consisting of porous NiO nanosheets and flower-like ZnO assembled by hexagonal nanorods was successfully fabricated by a simple two-step hydrothermal approach. Flower-like ZnO was obtained by the first step hydrothermal method. Through the second step hydrothermal method, porous NiO nanosheets grew on the surface of flower-like ZnO to realize integration of ZnO and NiO, so the p-n heterostructure between ZnO and NiO formed. The samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX). Gas sensing test results showed that the sensor based on NiO/ZnO composite exhibited superior sensing properties to acetone. The sensor response to 100 ppm acetone was about 205.14 at the optimum working temperature of 240 °C, and the response and recovery times were about 7 and 20 s, respectively. The enhanced response might be attributed to heterojunction and larger specific surface area provided by attached porous NiO nanosheets. The rapid response and recovery characteristics and improved selectivity attributed to the porous structure and good catalytic actions of NiO nanosheets.     

TiB2掺杂WS2复合薄膜的宽温域摩擦学性能研究

目的 探究TiB2溅射电流(即TiB2含量)对WS2/TiB2复合薄膜在宽温域(25~500 ℃)下摩擦学性能的影响。方法 采用非平衡磁控溅射技术制备WS2/TiB2复合薄膜。通过场发射扫描电子显微镜(FESEM)、高分辨率透射电子显微镜(HRTEM)观察薄膜的形貌及结构;通过X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)表征薄膜结构;通过纳米压痕仪(Anton Paar,NHT²)评价薄膜的机械性能;利用高温球盘摩擦磨损试验机(THT01,03591)测试薄膜的摩擦学性能;采用光学显微镜(Olympus,STM6)、三维轮廓仪(Micro XAM–800)观察磨痕及磨斑形貌,通过HRTEM分析磨痕和磨斑的结构。结果 TiB2掺杂使WS2薄膜由高度结晶态向非晶态转变,增大了薄膜的致密度并提高了其机械性能。随着TiB2溅射电流的增大,复合薄膜的摩擦因数和磨损率呈先下降后上升的趋势。随着试验温度的升高,复合薄膜的摩擦因数先降低后升高,但磨损率一直逐渐升高。TiB2溅射电流为1.5 A时,制备的复合薄膜在宽温域(25~500 ℃)具有较低的摩擦因数和磨损率。300 ℃条件下,TiB2溅射电流为1.5 A时制备的复合薄膜在摩擦剪切力作用下重新定向形成了TiB2(101)晶体取向和平行于滑动方向的WS2(002)晶体取向,并在高环境温度和摩擦热作用下氧化形成了润滑相TiO2(001)晶体结构。结论 TiB2溅射电流为1.5 A时制备的复合薄膜具有优异的宽温域摩擦学性能。薄膜致密的非晶结构、高的硬度和弹性模量,以及在摩擦剪切力和高温氧化作用下重新结晶取向是低摩擦磨损的关键。