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松装烧结通孔材料透过颗粒最大半径的计算
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作者 丁志敏 《物理测试》 CAS 1995年第3期32-33,45,共3页
本文计算了在松装烧结条件下通孔材料透过颗粒的最大半径与原始颗粒尺寸和烧结后通孔材料密度的关系,在理想状态下,通孔材料透过颗粒的最大半径γ_0仅与原始颗粒半径γ有关。关系式为:γ_0=0.155γ;在实际条件下,透过颗粒最大半径γ_1... 本文计算了在松装烧结条件下通孔材料透过颗粒的最大半径与原始颗粒尺寸和烧结后通孔材料密度的关系,在理想状态下,通孔材料透过颗粒的最大半径γ_0仅与原始颗粒半径γ有关。关系式为:γ_0=0.155γ;在实际条件下,透过颗粒最大半径γ_1不仅与原始半径γ有关,而且还与烧结后通孔的密度ρ有关,关系式为:γ_1=(1.045(ρ_0/ρ)^(1/3)-1)γ,ρ_0为相应材质的理论密度。此关系式对用松装烧结法生产通孔材料具有一定的指导意义。 展开更多
关键词 松装烧结 通孔材料 粒度 粉末冶金
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通孔泡沫材料与分形理论 被引量:3
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作者 张金娅 左孝青 +2 位作者 史庆南 孙加林 刘荣佩 《昆明理工大学学报(理工版)》 2002年第4期13-15,共3页
分形理论是近年来发展起来的一种应用广泛的理论 .对通孔泡沫材料的孔结构和发泡过程进行了详细的分析 ,同时结合分形结构和分形动力学的相关理论 ,简要分析了二者之间的联系 ,提出了对通孔泡沫结构和孔结构生成过程分析的一个新的途径 .
关键词 分形理论 通孔泡沫材料 孔结构 发泡过程 分形结构 分形动力学
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液态金属限流器中电弧放电特性实验研究 被引量:2
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作者 孙毅卫 李珂 +4 位作者 孙振权 杨倬 何海龙 吴翊 纽春萍 《高压电器》 CAS CSCD 北大核心 2016年第6期109-114,共6页
电弧放电行为是影响磁收缩型液态金属限流器限流特性的关键因素之一。为了研究其电弧放电特性,设计了带有透明观察窗的单隔板实验装置,采用LC振荡回路模拟短路电流,进行了不同通孔材料下电弧行为及其演变特性的实验研究。结果表明:液态... 电弧放电行为是影响磁收缩型液态金属限流器限流特性的关键因素之一。为了研究其电弧放电特性,设计了带有透明观察窗的单隔板实验装置,采用LC振荡回路模拟短路电流,进行了不同通孔材料下电弧行为及其演变特性的实验研究。结果表明:液态金属电弧形态发展过程可分为起弧、电弧拉伸、弧区收缩及熄弧4个阶段。另外,通孔材料侵蚀所产生的强大气压会显著影响电弧行为及限流特性,一旦腔体内部气压过大,在燃弧后期易出现电弧在电流过零前熄灭的现象,不利于限流器对短路电流的限制。相较于石英玻璃,有机玻璃和GPO-3作为通孔材料可较大程度加快电弧发展、提高电弧电压,但其材料烧蚀严重影响限流器使用寿命,未来有必要继续探索新型耐高温材料。 展开更多
关键词 液态金属 磁收缩效应 电弧放电特性 气压测量 通孔材料
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Preparation of three-dimensional interconnected mesoporous anatase TiO_2-SiO_2 nanocomposites with high photocatalytic activities 被引量:4
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作者 董维阳 姚有为 +2 位作者 孙尧俊 华伟明 庄国顺 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第6期846-854,共9页
In this article, we report the preparation of a three-dimensional(3D) interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional(2D) hexagonal mes... In this article, we report the preparation of a three-dimensional(3D) interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional(2D) hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite(crystallized at 950 °C for 2 h) as a precursor, NaO H as an etchant of SiO2 via a "creating mesopores in the pore walls" approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform(average pore size 3.6 nm), and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B(RhB, 0.303 min^–1) and methylene blue(MB, 0.757 min^–1) dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance. 展开更多
关键词 PREPARATION Mesoporous anatase crystal-silica nanocomposite Three dimensional interconnected mesopores architecture Photocatalytic degradation Organic pollutants
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Wave Scattering by Porous Bottom Undulation in a Two Layered Channel 被引量:1
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作者 Sandip Pault Soumen De 《Journal of Marine Science and Application》 2014年第4期355-361,共7页
The scattering of plane surface waves by bottom undulations in channel flow consisting of two layers is investigated by assuming that the bed of the channel is composed of porous material. The upper surface of the flu... The scattering of plane surface waves by bottom undulations in channel flow consisting of two layers is investigated by assuming that the bed of the channel is composed of porous material. The upper surface of the fluid is bounded by a rigid lid and the channel is unbounded in the horizontal directions. There exists only one wave mode corresponding to an internal wave. For small undulations, a simplified perturbation analysis is used to obtain first order reflection and transmission coefficients in terms of integrals involving the shape function describing the bottom. For sinusoidal bottom undulations and exponentially decaying bottom topography, the first order coefficients are computed. In the case of sinusoidal bottom the first order transmission coefficient is found to vanish identically. The numerical results are depicted graphically in a number of figures. 展开更多
关键词 bottom undulations two-layer fluid porous bed reflection and transmission coefficients wave scattering
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跨越微观-宏观组装的桥梁:浓乳液聚合技术的应用 被引量:1
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作者 冯燕燕 金明 万德成 《化学进展》 SCIE CAS CSCD 北大核心 2016年第11期1658-1663,共6页
利用浓乳液(也称高内相比乳液)聚合技术可以获得表面结构化通孔材料(poly HIPE),其独特之处是藉此可以实现纳米级两亲体在宏观尺度上的表面有序组装,且可规模化生产。早期的poly HIPE以小分子表面活性剂稳定,仅提供了一个多孔骨架,因为... 利用浓乳液(也称高内相比乳液)聚合技术可以获得表面结构化通孔材料(poly HIPE),其独特之处是藉此可以实现纳米级两亲体在宏观尺度上的表面有序组装,且可规模化生产。早期的poly HIPE以小分子表面活性剂稳定,仅提供了一个多孔骨架,因为该表面活性剂易流失不能发挥表面功能基作用,而对惰性多孔骨架的后功能化往往较为繁琐。近年来,这方面的突破包括:(1)新型的Pickering稳定剂能同时发挥功能基作用;(2)以难迁移的两亲性嵌段共聚物代替易流失的小分子表面活性剂直接获得改性表面;(3)以带有大量活泼官能团的树状两亲体作稳定剂,直接获得表面由活泼基团表达的poly HIPE;(4)以金属纳米粒子-树状两亲体复合粒子作为稳定剂,直接获得表面由金属纳米颗粒表达的多孔材料。这些材料具有的尺寸大、易回收、比表面较高、具有结构化表面和能反复使用的特点,使其在超分子水处理、低泄漏金属催化剂方面有可观应用前景。 展开更多
关键词 高内相比乳液 通孔材料 树状两亲体 自组装 表面功能化 催化 水处理
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Breakup Structure of Two-phase Jets with Various Momentum Flux from a Porous Injector 被引量:2
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作者 Inchul Lee Dohun Kim Jaye Koo 《Journal of Thermal Science》 SCIE EI CAS CSCD 2014年第1期60-67,共8页
Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector... Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To in- crease atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear co- axial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial injector 展开更多
关键词 Porous injector Shear coaxial injector Breakup mechanism Momentum flux ratio
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