Novel one-step formed composite reinforcement of "Spider web like" SiCnw networks and "Z-pins like" SiC rods for ablation resistance improvement of C/C-ZrC-SiC

A novel composite reinforcement with horizontal multilayer "Spider web like" SiC nanowire networks and vertical interconnected "Z-pins like" SiC rods was designed and prepared by facile one-step figuration. The linear ablation rate of "Spider web like" SiC nanowire networks and "Z-pins like" SiC rods collectively reinforced C/C-ZrC-SiC composites at 2610 ± 20 ℃ was 0.4 ± 0.03 μm/s with a 74.19 % reduction. The improved ablation resistance was attributed to a denser gradient oxide layer composed of central ZrO₂ layer, transitional ZrO₂-SiO₂ layer and marginal SiO₂ layer generated under the initial sticky net effect from SiCnw networks and subsequent oxide compensation from "Z-pins like" SiC rods.     

Flash cosintering of a lanthanum strontium cobalt ferrite nanofibre/Gd-doped ceria bilayer structure

For solid oxide fuel cells, an important structural requirement is that the electrolyte layer needs to be dense and the electrode layer porous, which is difficult to obtain by conventional cosintering. In this work, flash cosintering of a double layer structure consisting of a Gd-doped ceria substrate with a lanthanum strontium cobalt ferrite nanofibre coating is investigated. Experimental and finite element modelling results reveal that when the LSCF layer is connected to the electrode, the heat is concentrated in the LSCF layer, which leads to a huge temperature gradient and introduces severe cracking. When the LSCF layer is electrically isolated from the electrode, the heat is concentrated in the GDC layer, and the temperature gradient is dramatically reduced. In this situation, the density of GDC can reach 92.86% while a high porosity of 52.26% is maintained in the LSCF layer, which is higher than that of the conventional cosintered sample.     

Dielectric and ferroelectric properties of multilayer BaTiO3/NiFe2O4 thin films prepared by solution deposition technique

In this work different lead-free multilayered structures, composed of perovskite BaTiO₃ and spinel NiFe₂O₄ thin layers, were obtained by solution deposition method. Structural characterization of the sintered thin films confirmed the well-defined layered structure with overall thickness from 160 to 600 nm, crystalline nature of perovskite BaTiO₃ and spinel NiFe₂O₄ phases without secondary phases (after sintering below 900 °C) and grains on nanometer scale. Dielectric properties of the multiferroic multilayer BaTiO₃/NiFe₂O₄ thin films were analyzed in temperature and frequency range from 30 °C to 200 °C and 100 Hz to 1 MHz, respectively. In comparison to the pure BaTiO₃ films, the introduction of ferrite layer reduces dielectric response and increases low frequency permittivity dispersion of the multilayer thin films. The multilayer samples have shown relatively low dielectric loss with stronger contribution of conductivity at higher temperatures, and characteristic broad peak representing “relaxation” of the interface charge accumulation.     

Concentration dependence of physical properties of low temperature processed ZnO quantum dots thin films on polyethylene terephthalate as potential electron transport material for perovskite solar cell

Colloidal Zinc oxide quantum dots (ZnO QDs) prepared with varying concentrations through precipitation method were deposited on flexible ITO/PET substrates using spin-coating technique. Various characterization tools were utilized to investigate the morphological, structural, electrical and optical properties of the films. The crystallinity of the films was found to improve with increasing ZnO QD concentration (ZQ_C) as evident from the X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) studies. Crystallographic and optical parameters were evaluated and explained in depth. The average nanograin size and bandgap were increased and decreased respectively, from ～5 nm to ～8 nm and 3.29 eV–3.24 eV with an increase in ZQ_C from 10 mg/mL to 70 mg/mL. Columnar structure growth of the films is revealed by AFM results. The films showed decent optical transparency up to 81%. All the ZnO films exhibited n-type semiconducting property as indicated by the electrical measurements with carrier mobility and low resistivity of 12.21–26.63 cm²/Vs and 11.84 × 10^?3 to 13.16 × 10^?3 Ω cm respectively. Based on the experimental findings, ZnO QD nanostructure film grown at 50 mg/mL is envisaged to be a potential candidate for flexible perovskite photovoltaic application.     

Transparent and anti-fogging AlPO4-5 films constructed by oblique oriented nano-flake crystals

In the present work, transparent and anti-fogging AlPO₄-5 films were prepared on glass substrates using a novel developed process. The process entails a simple in-situ sol–gel followed by vapor phase transport. The in-situ sol–gel process was implemented by coating the precursor sols for the synthesis of AlPO₄-5 on the glass substrates successively using the spin-coating method. The films and powders scribed from the films were characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy and transmission electron microscope (TEM). The unique films were composed of oblique oriented nano-flake AlPO₄-5 crystals with the thickness of about 20 nm. The formation of nano-flake crystals can be ascribed to the high concentration of the precursors, resulting in the formation of a supersaturation system. The obtained films showed high antifogging performance due to the superhydrophilicity with a water contact angle of lower than 1.0°. The silicone oil contact angle was also low about 8.2°. In addition, heteroatom-substituted AlPO₄-5 films showing different colors can be obtained easily by simply adding transition metal ions in the phosphate acid solution during the preparation that can extend the application of the method for different coating demand.     

高湿环境对洗衣凝珠安全性能的影响

在高湿环境条件下,洗衣凝珠吸水增重后,其耐压强度随着水分含量的增加而衰减,当吸水量达到8％左右(水分含量约16％)时,耐压强度会下降50％～70％.随着洗衣凝珠市场份额不断增加,洗衣凝珠逐渐普及,仅百度搜索"误食洗衣凝珠"就有三千多万相关结果,我们需关注高湿条件下对其安全性能挑战,建议生产厂家充分考虑洗衣凝珠耐压强度指...     

孔径法测量铜带残余应力的试验研究

介绍了用于薄板残余应力测量的新方法——孔径法,该方法是通过测量冲孔直径的变化来间接求出各方向的残余应力;文中详细阐述了残余应力的标定方法;由于可针对不同材料建立了被测材料的平均应力(σ_l)与被测板材宽度(B)、厚度(H)以及冲孔后直径变化率(△D_i/D)之间的数学模型,因而使薄板残余应力测量变得简便而经济;此外还对该方法的分辨率与测量精度进行了实验、计算与分析。     

不可压缩液体中受纵向压力薄板的稳定

分析了不可压缩液体中受纵向压力薄板的屈曲形式,与通常情况下的受压薄板做了对比。指出由于不可压缩液体的影响,受压薄板的稳定性可以得到明显提高。     

文克勒地基上圆形薄板受轴对称载荷作用的贝塞尔函数解

利用贝塞尔函数给出了文克勒地基上圆形薄板受轴对称载荷作用解的解析表达式,并计算了文克勒地基上受均布载荷作用的圆形薄板的挠度,给出了挠度曲线.     

大口径（φ125mm）紫外（248nm）介质膜镀制

报导了用ＤＭＤ－４５０机镀制大口径（φ１２５ｍｍ）紫外（２４８ｎｍ）均匀高反膜及增透膜，工装简单实用，解决了大口径基片的放置，用可见光监控紫外涂镀及膜片均匀性三个问题，摸索了氧化铪膜料蒸发工艺。结果达到激光器要求。