磨料射流切割机的试验研究

本文介绍了前混合式磨料射流切割机的结构,工作原理以及用该机对金属和非金属材料进行的切割试验,指出射流工作压力、喷射靶距、喷嘴横移速度、磨料重量比浓度等是影响工作能力的主要因素,喷嘴直径及其内腔结构、磨料粒子尺寸等也是影响割缝宽度及表面形态的因素.试验对此表明,它比纯高压水射流和后混合式磨料射流切割机性能优越,是一种新型的、有广阔应用前景的工业切割设备.     

面向RPST的氩氮等离子射流温度分布的测量

在假定等离子体处于局域热力学平衡与光学薄条件下 ,用谱线绝对强度法测量了在等离子熔射快速制模(RPST)过程中氩氮等离子射流的温度分布。实验由CCD装置采集等离子射流图像 ,通过标定实验建立射流图像灰度和辐射强度之间的函数关系并应用Abel变换最终得到射流的温度场分布。获取的温度场将为RPST熔射工艺的合理设计提供科学依据     

Solution processable PEDOT:PSS based hybrid electrodes for organic field effect transistors

We report high performance solution processed conductive inks used as contact electrodes for printed organic field effect transistors (OFETs). Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) electrodes show highly improved very low sheet resistance of 65.8 ± 6.5 Ω/square (Ω/□) by addition of dimethyl sulfoxide (DMSO) and post treatment with methanol (MeOH) solvent. Sheet resistance was further improved to 33.8 ± 8.6 Ω/□ by blending silver nanowire (AgNW) with DMSO doped PEDOT:PSS. Printed OFETs with state of the art diketopyrrolopyrrole-thieno[3,2-b]thiophene (DPPT-TT) semiconducting polymer were demonstrated with various solution processable conductive inks, including bare, MeOH treated PEDOT:PSS, single wall carbon nanotubes, and hybrid PEDOT:PSS-AgNW, as the source and drain (S/D) electrode by spray printing using a metal shadow mask. The highest field effect mobility, 0.49 ± 0.03 cm² V⁻¹ s⁻¹ for DPPT-TT OFETs, was obtained using blended AgNW with DMSO doped PEDOT:PSS S/D electrode.     

Microstructural characterization of spray-dried NiO-8YSZ particles as plasma sprayable anode materials for metal-supported solid oxide fuel cell

The plasma spray method is widely used to produce NiO-8YSZ (composed of nickel oxide (NiO) and 8 mol% yttria-stabilized zirconia) anode layers in metal-supported solid oxide fuel cell (SOFC). Flowability control of microsized particles is important for achieving consistent performance of the SOFC anode layer. When microsized particles are fabricated via spray drying and sintering, the most significant factors that influence flowability are their sizes, distribution, and surface conditions. Thus, the aim of this study is to analyze the fabrication conditions for microsized NiO-8YSZ cermet particles made from a nanoscale, sinterable NiO-8YSZ dispersion solution by using an appropriate spray-drying and sintering process. The characteristics of the as-sprayed and sintered NiO-8YSZ composite particles (such as size, distribution, roughness, and nanostructure) were analyzed via field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), particle size distribution (PSD), Brunauer–Emmett–Teller (BET) surface area, and atomic force microscopy (AFM). The as-sprayed microsized NiO-8YSZ particles became smaller and more uniformly distributed as the rotational speed used for spray drying increased. As a result of sintering, the extent of shrinkage of as-sprayed microsized NiO-8YSZ particles generated at high RPMs was lower than that of particles formed at low RPMs. No significant difference was observed in the distribution of the nanosized NiO and 8YSZ particles at different rotational speeds. Furthermore, the highest BET surface areas were observed for particles generated at 8000 RPM before sintering at 13.74 m²/g. After sintering, the highest BET surface area was 0.94 m²/g for particles generated at 16,000 RPM. Differences in nanostructure and surface roughness between as-sprayed and sintered microsized NiO-8YSZ particles were identified via AFM. This study is expected to provide important fundamental information useful for optimizing SOFC efficiency by promoting flowability control during the production of SOFC anodes via plasma spraying.     

节能型清洁喷雾干燥技术

传统的催化剂喷雾干燥系统多采用直接干燥工艺,载气与待干燥物料直接接触换热,这样会对某些特性的催化剂造成污染,影响产品的最终品质,且高温尾气不经回收直接排入大气,造成热量损失。基于此,开发了一种节能型催化剂清洁喷雾干燥技术,即:利用新型结构的间接式热风炉提供清洁的干燥热风,利用尾气半循环使部分高温清洁尾气回用,实现了节能型、清洁型喷雾干燥工艺。     

Experimental study of drop impacts and spreading on epicarps: Effect of fluid properties

The fluid mechanic of liquid drop impacts on solid food plays an important role in food engineering, e.g. when a spray technology is used to apply a coating. In the present work, drop impact behavior on banana and purple cabbage epicarps using high speed camera was studied. Drop velocity was controlled by modifying the height from which drop was ejected. Weber number varied from 100 to 800, whereas Reynolds number ranged from 1000 to 12,500. Liquid drop viscosity and surface tension effects on drop impact behavior were evaluated and temporal evolution of both spreading and flattening factors are presented. Results show that viscosity and epicarp surface properties had great influence on impact dynamics. For low viscosity liquid drops (water and Tween 20-water), the maximum spread factor, ξ_max, scaled with We^0.25±0.02, whereas for viscous fluid (water-glycerol mixture) it scaled with We^0.16±0.02. Finally, a new model was proposed to better fit the experimental data than the Roisman’s and Scheller’s models.     

Influences of post-annealing temperature on the structural and electrical properties of mixed oxides (CuFeO2 and CuFe2O4) thin films prepared by spray pyrolysis technique

P-type mixed oxides (CuFeO₂ and CuFe₂O₄) transparent conducting thin films have been successfully deposited on p-type Si (111) substrates at 450 °C by spray pyrolysis deposition (SPD) and annealed at 800 °C for 2 h. The crystal structure, surface morphology and electrical property have been investigated. It is observed that the CuFeO₂ and CuFe₂O₄ thin films as deposited and annealed, have polycrystalline hexagonal structure and the crystallite size increases by annealing processes. The electrical property of the Ni/CuFeO₂/Si Metal–Semiconductor–Metal (MSM) photo detectors was investigated using the current–voltage (I–V) measurements. The barrier heights ϕ_Β of Ni/CuFeO₂/Ni MSM thin films of as deposited and annealed on Si substrates were calculated and its values are 0.478, 0.345 eV, respectively with an applied bias voltage of 3 V.     

Spray pyrolysis deposition of Cu–Zn–In–S solid-solution thin films with tunable compositions and band gaps

Cu–Zn–In–S solid solution thin films with tunable compositions and band gaps were deposited on glass substrates using a chemical spray pyrolysis approach. XRD results reveal the cubic-structured Cu–Zn–In–S films without detectable impurities. The successive shift of XRD patterns toward high-angle side of ZnS with increasing ZnS molar fraction in products proves a formation of Cu–Zn–In–S solid solutions. SEM images and EDAX analyses demonstrate homogeneous surface morphologies and adjustable compositions of Cu–Zn–In–S films, which results in film band gaps broadly tunable from 1.54 eV to 3.61 eV. These sprayed Cu–Zn–In–S solid solution thin films may find potential uses in photovoltaics and photocatalysis.     

A novel insight to screen the optimal spray-drying protectants and parameters for manufacturing lactic acid bacteria preparations

Abstract

This study constructed a β-galactosidase (β-gal) liposome model instead of bacterial cells to optimize spray-drying protectants and parameters. The screened protectant combination consisted of 35?g/L monosodium glutamate, 50?g/L sucrose, and 35?g/L maltodextrin. The optimal parameters for spray drying were 130?°C inlet air temperature, 7.5?mL/min feed flow rate, and 150?mL optimal protectant combination. The viability of the five lactic acid bacteria strains spray-dried with the optimized protectant and parameters was over 50%. Lactobacillus helveticus strain LH-9’s mechanism of resistance to spray-dry treatment was investigated in the presence of the optimal protectant combination.