Electrospun nylon 6,6 nanofibers functionalized with cyclodextrins for removal of toluene vapor

Functional nylon 6,6 nanofibers incorporating cyclodextrins (CD) were developed via electrospinning. Enhanced thermal stability of the nylon 6,6/CD nanofibers was observed due to interaction between CD and nylon 6,6. X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy studies indicated the existence of some CD molecules on the surface of the nanofibers. Electrospun nylon 6,6 nanofibers without having CD were ineffective for entrapment of toluene vapor from the environment, whereas nylon 6,6/CD nanofibrous membranes can effectively entrap toluene vapor from the surrounding by taking advantage of the high surface‐volume ratio of nanofibers with the added advantage of inclusion complexation capability of CD presenting on the nanofiber surface. The modeling studies for formation of inclusion complex between CD and toluene were also performed by using ab initio techniques. Our results suggest that nylon 6,6/CD nanofibrous membranes may have potential to be used as air filters for the removal of organic vapor waste from surroundings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41941.     

Microstructure and mechanical properties of yttria stabilized zirconia coatings prepared by plasma spray physical vapor deposition

Plasma spray physical vapor deposition (PS-PVD) was used to deposit yttria stabilized zirconia (YSZ) coatings with different columnar morphologies by varying the spray distance. Although similar quasi-columnar structures were formed at the spray distances of 600 mm and 1400 mm, the formation mechanisms of particles in the coatings were different. Besides, an electron beam physical vapor deposition (EB-PVD) like columnar coating out of pure vapor was deposited at a spray distance of 1000 mm and the columnar consisted of elongated nano-sized secondary columns. The hardness and Young׳s modulus of the coatings were investigated. Compared to the other two quasi-columnar structures, the EB-PVD like columnar coating exhibited higher hardness (~9.0 GPa ) and Young׳s modulus (~110.9 GPa), mainly due to its low porosity and defect.     

基于纯声子散射模型的梯度阻热涂层热力分析

梯度阻热涂层(由不同混合比的阻热涂层和底层材料组成)可以降低阻热涂层(陶瓷)材料和底层(金属)材料之间因热失配而产生的热应力.结合纯声子散射模型(用于梯度阻热涂层)与傅里叶热传导模型(用于底层),用数值方法求解梯度阻热涂层的温度场和应力场,研究了阻热涂层参数(松弛时间、声子速度)梯度分布对温度场的影响以及阻热涂层力学性能(弹性模量、热膨胀系数)梯度分布对热应力的影响.结果表明:阻热涂层参数梯度分布能明显减小梯度阻热涂层的温度梯度;阻热涂层力学性能梯度分布能降低梯度阻热涂层的热应力,其中热膨胀系数梯度分布的影响明显大于弹性模量梯度分布的影响.     

Optical and structural properties of sol-gel derived nanostructured CeO_2 film

Sol-gel derived nanostructured CeO2 film was deposited on glass substrate using the dip-coating technique with annealed at 650oC. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), UV/VIS and photoluminescence (PL) spectroscopy studies were employed to analyze the structural and optical properties of the sol-gel derived nanostructured CeO2 film. The average crystallite size was estimated from XRD pattern using Scherrer equation as about 3–4 nm. SEM micrograph shows the film have good adherence to the substrate, porous in nature and crack free. The UV-visible absorption spectroscopic measurement results showed that the products had conspicuous quantum size effects. The absorption spectrum indicates that the sol-gel derived nanostructured CeO2 film have a direct bandgap of 3.23 eV and the photoluminescence spectra of the film show strong band at 378 nm may have promising applications as optoelectronic materials.     

Scratch Resistance Enhancement of Polymer Coatings

This review presents the state of the art regarding the improvement of scratch resistance of polymeric coatings. In particular, our attention is focused on the effect of inorganic nanometric fillers on the scratch resistance of organic coatings. Two main strategies are described for the achievement of such nanostructured hybrid organic/inorganic coatings: either a top‐down or a bottom‐up approach.

     

Optical and structural properties of sol-gel derived nanostructured CeO2 film

Sol-gel derived nanostructured CeO2 film was deposited on glass substrate using by dip-coating technique with annealing at 65℃.X-ray diffraction (XRD),scanning electron microscopy (SEM),Fourier transform infrared (FTIR),UV/vis and photoluminescence (PL) spectroscopy studies were employed to analyze the structural and optical properties of the sol-gel derived nanostructured CeO2 film.The average crystallite size was estimated from the XRD pattern using by Scherrer equation as about 3-4nm.An SEM micrograph shows that the film was porous in nature and crack free.The UV-visible absorption spectroscopic measurement results showed that the products had conspicuous quantum size effects.The absorption spectrum indicates that the sol-gel derived nanostructured CeO2 film has a direct bandgap of 3.23 eV and the photoluminescence spectra of the film show a strong band at 378 nm:it may have a promising application as an optoelectronic material.     

Investigating the thermal,mechanical and thermal cyclic properties of plasma-sprayed Al2O3-7YSZ/7YSZ double ceramic layer TBCs

Double ceramic layer (DCL) TBCs consisting of a top 20 wt.% Al₂O₃-7YSZ layer and a bottom 7YSZ layer were desirably designed to achieve preferable performance while the thermal, mechanical and thermal cyclic properties were comprehensively investigated. Compared to the conventional 7YSZ TBCs, the thermal insulation properties of the DCL coating were significantly improved due to the increased oxygen vacancy concentration induced by Al₂O₃ addition while the thickness of the thermally grown oxides was diminished by the decreased oxygen diffusion rate. Furthermore, the improved fracture toughness of the DCL coating also prolonged the thermal cyclic life.     

溅射沉积Cu/W纳米多层膜结构与性能

以单晶硅和聚酰亚胺为衬底,用磁控溅射沉积调制周期λ=25~150 nm、调制比η=0.5~2的Cu/W纳米多层膜,用XRD、SEM、EDS、AFM、微力测试系统、纳米压痕仪和四探针法对多层膜微观结构、表面形貌和力学及电学性能进行研究。结果表明:λ和η显著影响多层膜结构和性能。多层膜Cu层和W层均为纳米晶结构,分别呈Cu(111)和W(110)择优取向。W(110)晶面间距减小且减幅与1/λ或η值呈正相关,Cu/W层间界面处存在扩散混合层。表面Cu层晶粒尺寸随Cu层厚增加而增大。裂纹萌生临界应变εc总体上随λ增大或η减小而下降,屈服强度σ0.2、显微硬度H和电阻率ρ总体上均与λ或η呈负相关。因Cu层和W层厚度随λ或η的变化而改变,相应地改变了Cu层晶粒度及其晶界密度、W层体积分数和Cu/W层间界面数量,使位错运动能力及电子散射效应变化,最终改变Cu/W纳米多层膜性能。     

Thermal modeling of plasma spray deposition of nanostructured ceramics

A thermal model for plasma spray deposition of ceramic materials onto metallic substrates has been developed. The enthalpy-based control volume formulation of the heat transfer processes has been used to study the temperature evolution in a two-dimensional substrate and in the coating as it is grown. In this paper, additional melting of ceramic splats after deposition is examined, with a view to predicting the retention of nanostructures in a spray consisting of agglomerated, nanometer-sized particles. Initial results for thin coatings indicate that when the mean temperature of the incoming particles is close to the fusion point of the ceramic material, the nanostructure distribution in the coating is largely determined by the composition of the spray. However, with thicker coatings, additional melting due to prolonged plasma gas heating combined with increased thermal resistance in the underlying coating leads to a loss of nanostructure.     

Synthesis and characterization of La（OH）_3 nanopowders from hydrolysis of lanthanum carbide

The lanthanum carbide alloy was induction melted in vacuum induction melting furnace from lanthanum and graphite with the mass ratio of 89:11. Lanthanum hydroxide (La(OH)3) nanopowders were prepared by a simple hydrolysis of lanthanum carbide at room temperature under normal atmospheric pressure without any surfactant. X-ray diffraction (XRD) showed that the nanoparticles were with a hex-agonal structure. The effect factors such as reaction time,reaction temperature and the mass ratio of lanthanum carbide p...