烧成温度对合成莫来石陶瓷膜的影响

以正硅酸乙酯、硝酸铝和氟化铝为原料,采用溶胶一凝胶法在多孔莫来石陶瓷载体上原位反应烧结合成了晶须状多孔莫来石陶瓷膜.考察了在1 200,1 300,1 400,1 500℃烧成温度、保温2 h后对莫来石相及其膜层表面微观结构的影响.结果发现:在烧成温度为1 300℃时出现了莫来石相,并随着烧成温度的升高,莫来石相的特征峰增强;在氟化铝质量分数为10%、1 500℃保温2 h条件下,膜层表面生长出长为2.5μm、宽为0.5 μm、长径比(长/宽)为5的莫来石晶须,并且此时形成的莫来石晶须比较均匀,莫来石陶瓷膜平均孔径为0.75μm左右,纯水通量为725 L/(m2·h).     

钛涂覆多孔羟基磷灰石涂层的制备及其生物活性

在纯钛基体表面通过电泳沉积的方法制得壳聚糖/羟基磷灰石(CS/HA)复合涂层, 然后将复合涂层烧结形成多孔HA涂层。采用SEM对多孔HA涂层的形貌进行观察, XRD分析涂层的物相组成, 粘结拉伸实验测定涂层与基体的结合强度, 1.5倍人体模拟体液(1.5SBF)浸泡测定涂层的生物活性。结果表明: 当悬浮液中CS与HA质量比为1∶1时, 制得的CS/HA复合涂层经过700℃烧结处理, 涂层中CS热分解致孔形成多孔HA涂层, 孔径在10~25 μm, 涂层与基体的结合强度可达19.5 MPa; 在1.5SBF中浸泡5天后, 多孔HA涂层表面完全碳磷灰石化, 呈现较好的生物活性。      

用于过滤膜的梯度孔径Ni-Cr-Fe多孔材料的制备及性能

本工作采用元素粉末反应合成法,利用固相偏扩散的原理进行固相烧结制备Ni-Cr-Fe多孔材料支撑体,再利用人工刷涂的方法将同配比且较细的Ni、Cr、Fe元素粉末悬浮浆料刷涂于多孔支撑体表面,经过真空烧结,制备得到梯度孔径Ni-Cr-Fe多孔材料。通过XRD、SEM、能谱等测试手段表征烧结后的梯度孔径Ni-Cr-Fe多孔材料的物相及孔结构性能。结果表明,同质的梯度孔径Ni-Cr-Fe多孔材料膜层完整,结合强度较好,以冶金桥接的方式结合。随着膜层厚度的增加,透气度将减小,当过渡层的厚度为80μm,表面膜层厚度为30μm时,最大孔径为6μm,透气度为936 m~3·m~(-2)·h~(-1)·kPa~(-1),透气度下降22. 64%。在膜层等厚且过滤精度达到要求时,二阶梯度孔径Ni-Cr-Fe多孔材料透气度的下降率比一阶梯度孔径NiCr-Fe多孔材料透气度的下降率小。过渡膜层起到了非常关键的作用,实现了在较高过滤精度的基础上具有较大的过滤通量。     

多孔镍载体材料的制备

试验在常规粉末冶金方法基础上通过添加造孔剂的办法制备出高孔率(70%以上)、小孔径(最大冒泡孔径＜5 μ m)、高透过量,通孔率(通孔率可达97%以上)的多孔镍载体材料.主要进行了粉末粒度及形貌的分析选择研究,造孔剂的添加量与多孔镍载体性能关系的研究、烧结工艺对材料性能影响的研究.主要从孔率、最大冒泡孔径、透气系数、通孔率等方面着手,研究了造孔剂加入量及烧结工艺对该性能的影响,同时对不同条件下样品的性能进行了测试.     

炭辅助的固态粒子烧结工艺制备多孔TiO2/不锈钢膜

提出了一种炭辅助的固态粒子烧结工艺, 可在大孔烧结金属载体表面直接制得无过渡层的多孔陶瓷膜。以纳米TiO₂为成膜粒子, 以大孔不锈钢滤管为载体, 以聚乙烯醇(PVA)为粘结剂, 采用浸渍提拉法在载体表面涂覆。考察了不同烧结气氛(氮气和空气)对陶瓷膜制备的影响。通过扫描电子显微镜、X射线衍射、热重分析和孔径测试对材料进行表征。实验发现, 试样在空气中烧结后膜层发生严重剥落, 而在氮气中烧结后膜层完整。这是由于PVA在氮气中高温碳化生成炭, 所形成的TiO₂和炭的混合结构削弱了因载体表面状况差和陶瓷—金属间热膨胀系数不匹配而引起的陶瓷层烧结应力。待陶瓷颗粒烧结后, 涂层中的炭经空气热处理脱除。所制备的多孔TiO₂/不锈钢膜的膜层厚度约10 μm, 平均孔径为0.21 μm, 室温下氮气通量为1.72 m³/(m²·h·kPa)。     

壳聚糖修饰纳米羟基磷灰石/聚酰胺复合多孔支架的制备及性能研究

利用相转移法制备了纳米羟基磷灰石/聚酰胺66(n-HA/PA66)复合多孔支架.用不同浓度(1%、3%、5%)的壳聚糖(CS)溶液对多孔支架进行了表面修饰.用扫描电镜(SEM)和材料力学试验机对多孔支架修饰前后的形貌和力学性能进行了表征.研究了经CS修饰的n-HA/PA66复合多孔支架在磷酸盐缓冲溶液(PBS)中的浸泡行为,并初步研究了其与MG63细胞的细胞相客性.结果显示,多孔支架具有较为理想的孔隙结构和贯通性,经CS修饰后,其力学强度有显著提高.体外浸泡结果显示,随着漫泡时间的增加,支架表面微结构变得粗糙和多孔化.细胞实验表明该支架有利于细胞在表面的粘附、铺展、生长和增殖.     

宇部兴产开发聚酰亚胺多孔质膜

日本宇部兴产改进以往聚酰亚胺制膜技术和分离膜制造技术 ,采用独自的方法开发成功世界首创的聚酰亚胺多孔质膜。用以往方法制的聚酰亚胺膜因在外表面形成一致的非对称结构 ,使两表面及内部结构从而形成孔径空孔 ,较难制成均质多孔质膜 ,从而使其在过滤器、分离器等方面的应用受到阻碍。宇部兴产开发的聚酰亚胺多孔质膜以二苯基四羧酸二酐 (ＢＰＤＡ)和芳香族二胺为原料 ,膜断面方面具有贯通孔 ,且表面无绵密层。膜内具有均质连续微孔 ,空孔率30 %～ 80 % ,平均孔径 0 0 1～ 5 μｍ ,膜厚 5～ 10 μｍ ,透气度30秒 / 10 0ＣＣ～ 2 0 0 0秒 …     

丝素蛋白/纳米生物玻璃复合多孔支架的结构与性能

采用冷冻干燥法制备了丝素蛋白(SF)/纳米生物玻璃(NBG)复合多孔支架材料。并用XRD、FT-IR、SEM等对SF/NBG复合支架进行了结构与性能表征。结果表明,SF/NBG复合多孔支架孔连通性较好,孔径为150～300μm,孔隙率为80.6%～90.3%;同时NBG的加入促进了复合多孔支架中SF的构象部分由无规卷曲向β-折叠转变。复合多孔支架抗压强度和抗压模量相比于纯SF多孔支架有较大提高。采用模拟体液浸泡实验研究了复合支架的体外生物活性,并用XRD、FT-IR和FESEM对试样表面进行了表征。结果显示,复合多孔支架经模拟体液浸泡7d后,表面沉积出类骨羟基磷灰石(HA)层,NBG的加入能加快复合多孔支架表面沉积类骨HA的速度。研究结果显示SF/NBG复合多孔支架材料有望作为生物活性良好的骨组织修复材料。     

聚酰胺多孔膜的可控制备及细胞生物学响应

利用相转移法,通过控制溶剂蒸发温度制备了不同孔隙结构的聚酰胺(PA)多孔膜,用扫描电镜(SEM)和材料力学试验机对不同孔隙结构的PA多孔膜的形貌和力学性能进行了表征。将PA多孔膜与类成骨细胞(MG63)共培养来考察不同孔隙结构多孔膜的细胞生物学响应。结果表明,随着溶剂蒸发温度升高,制备的PA多孔膜孔径大小逐渐增大,在40℃下制备的多孔膜孔隙结构均匀,孔径为10~20μm,其弹性模量与拉伸强度分别达到(20.2±0.9)和(5.2±0.5)MPa。细胞实验表明,与40℃下制备的PA多孔膜共培养后,细胞在其表面伸展爬行,形态结构完整,增殖明显。具有可控特性的PA多孔膜能够满足其在骨组织引导再生临床中的应用。     

连续梯度金属多孔材料的研究

梯度金属多孔材料是孔径或孔隙率沿厚度方向变化的一类金属多孔材料,也叫非对称金属多孔材料或微孔金属膜,由孔径较大的支撑体和孔径较小的精度控制层组成。支撑体主要起骨架增强作用,精度控制层主要拦截颗粒。采用离心沉积的方法,在模具腔内壁形成梯度粉末层坯料,取出坯料进行干燥、烧结后获得连续梯度金属多孔材料。过滤试验表明,在相同精度等级下,该梯度多孔材料的透过性能是常规相同孔径金属多孔材料的10倍以上,是突变孔径梯度金属多孔材料的3倍以上。羰基铁高压分解气过滤应用表明,连续梯度金属多孔材料具有精度高、处理量大等特点。与常规金属多孔材料相比,在羰基铁高压分解气过滤等方面具有明显优势,气固分离精度可达0.35μm,运行压差小于20 k Pa。     

Permeation of solvents through disk type rice husk silica membrane modified with alkyl silylation reagents

Rice husk silica (RHS) which was obtained with thermal treatment of rice husk has the size of approximately 10 micrometer with 4-5 nm pore. RHS can be mold to a disk type membrane. The membrane may have submicron pore originated from the space among the particles, and the nano pores of the rice husk silica (RHS pore). Even it is difficult to adjust the size of the pores, we can suggest that the membrane shows different permeability for the organic/inorganic solvents if the affinity between the surface of the pores and the permeating molecule is changed. In this study, we investigated the permeation of the typical solvents such as water, ethanol and toluene to the RHS membranes sintered at 1100 degrees C, 1150 degrees C and 1200 degrees C and modified with triethoxymethyl silane (CH3)Si(C2H5O)3, diethoxydiemethyl silane (CH3)2Si(C2H5O)2 and ethoxytriemethyl silane (CH3)3Si (C2H5O). The result showed that permeability of original membranes for water (e.g., 1100 degrees C, 2.87 x 10(-3) mol/m2 s Pa) was larger than ethanol (1100 degrees C, 5.51 x 10(-4) mol/m2 s Pa) and toluene (1100 degrees C, 3.09 x 10(-4) mol/m2 s Pa) at the sintering temperatures. For the silane modified membranes, the permeability for water decreased drastically while those for ethanol and toluene increased.     

Porous FeAl alloys via powder sintering:Phase transformation,microstructure and aqueous corrosion behavior

This study investigates the phase transformation and microstructure of porous FeAl parts sintered from elemental powder mixtures using in-situ neutron diffraction and in-situ thermal dilatometry.A single B2 structured FeAl phase was determined in the sintered FeAl alloy.The combined effects of the Kirk-endall porosity,transient liquid phase,and phase transformations associated with powder sintering all contribute to the swelling phenomenon of the final sintered part.The aqueous corrosion test indicates that the corrosion products include iron oxides in the porous FeAl parts.The accumulation of corrosion products blocks the pore channel and decreases pore size and permeability over the soaking time.     

新型多孔碳化硅陶瓷膜管的制备与性能表征

以SiC为骨料,选用低共熔混合物作为烧结助剂,用液相烧结技术制备出单通道多孔陶瓷支撑体,采用悬浮粒子浸涂法对支撑体涂覆氧化铝膜.考察了氧化铝膜、烧成温度对支撑体孔径分布和空气渗透通量等性能的影响.结果表明:涂膜后膜管的孔径分布变窄,空气渗透通量略有下降;随着烧结温度的提高,结合剂的高温特性使得支撑体的开孔率和空气渗透通量分别下降了1.9%和17.9 m3/(m2·h),孔径分布变宽,平均孔径增大.     

聚醚砜中空纤维超滤膜的孔径大小及分布

对测定中空纤维超滤膜孔径大小及其分布的物质迁移方程法进行了改进，并考察了浓度对聚醚砜（ＰＥＳ）中空纤维膜孔径大小及其分布的影响．随纺丝液中ＰＥＳ质量浓度的增大，膜的孔径变小，对聚乙二醇的表观截留率增大，膜的纯水透过率减小，在大约２４％的ＰＥＳ质量浓度时出现临界值，大于该临界值，膜的结构和性能均发生急剧变化．     

Hydraulic properties of porous sintered glass bead systems

In this paper, porous sintered glass bead packings are studied, using X-ray Computed Tomography (XRCT) images at \(16\,\upmu \hbox {m}\) voxel resolution, to obtain not only the porosity field, but also other properties like particle sizes, pore throats and the permeability. The influence of the sintering procedure and the original particle size distributions on the microstructure, and thus on the hydraulic properties, is analyzed in detail. The XRCT data are visualized and studied by advanced image filtering and analysis algorithms on to the extracted sub-systems (cubes of different sizes) to determine the correlations between the microstructure and the measured macroscopic hydraulic parameters. Since accurate permeability measurements are not simple, special focus lies on the experimental set up and procedure, for which a new innovative multi-purpose cell based on a modular concept is presented. Furthermore, segmented voxel-based images (defining the microstructure) are used for 3D (three-dimensional) lattice Boltzmann simulations to directly compute some of the properties in the creeping flow regime. A very good agreement between experimental and numerical porosity and permeability could be achieved, in most cases, validating the numerical model and results. Porosity and permeability gradients along the sample height could be related to gravity acting during sintering. Furthermore, porosity increases in the outer zones of the samples due to the different contact geometry between the beads and the confining cylinder wall during sintering (which is replaced by a membrane during permeability testing to close these pores at the surface of the sample). The influence of different filters on the gray scale distributions and the impact of the segmentation procedure on porosity and permeability is systematically studied. The complex relationships and dependencies between numerically determined permeabilities and hydraulic influence parameters are investigated carefully. In accordance to the well-known Kozeny–Carman model, a similar trend for local permeability values in dependence on porosity and particle diameter is obtained. Other than statistical models, which estimate the pore throat distribution on the basis of the particle size distribution, in this study XRCT scans are used to determine the pore throats in sintered granular systems, which are finally linked to the intrinsic permeability through the lattice Boltzmann simulations. From the \(\mu \)XRCT analysis two distinct peaks in pore throat distributions could be identified, which can be clearly assigned to typical pore throat areas occurring in polydisperse granular systems. Moreover, a linear dependency between average pore throat diameter and porosity as well as between permeability and pore throat diameter is reported. Furthermore, almost identical mean values for porosity and permeability are found from sub-system and full-system REV analysis. For sintered granular systems, the empirical constant in the classical Kozeny–Carman model is determined to be 131, while a value of 180 is expected for perfect mono-disperse sphere packings.     

水性聚氨酯膜的制备及在超纤革中的应用

以水性聚氨酯(WPU)为聚合物,采用物理机械发泡的方法制备WPU膜,系统研究了成膜温度对WPU膜形态结构和性能的影响规律。结果表明,当成膜温度低于100℃时,所制备WPU膜的泡孔密度、表面孔孔径、平均孔径、结晶度、透气量、透湿率、断裂强度和断裂伸长率等均随成膜温度的升高而增大。其中,当成膜温度为80℃时,膜具有最佳的性能。随着成膜温度进一步升高,膜的表面出现裂纹,透气量和透湿率增加,而断裂强度和断裂伸长率显著减小。在此基础上,经干法移膜技术制备的WPU超纤革达到了成品等级的A类产品。     

Plasma modification of polyacrylonitrile ultrafiltration membrane

Polyacrylonitrile (PAN) ultrafiltration (UF) membranes were modified by plasma treatments and plasma polymerization. Influences of plasma modifications on membrane characteristics were investigated. The obtained results indicated that plasma treatments using non-polymer-forming plasma gases such as Ar, He and O₂ led to the increase of membrane surface hydrophilicity and membrane permeability. By using O₂ plasma treatment, UF property of PAN membranes could be improved with the enhancement of membrane flux meanwhile its albumin rejection was almost maintained. The experimental results also showed that plasma polymerization using acrylic acid vapor as monomer and PAN UF membrane as a substrate led to the formation of reverse osmosis membrane due to the deposition of plasma polymer layer onto substrate membrane surfaces. Plasma techniques can control membrane pore size and have a potential to improve the membrane characteristics by using their advantages.     

石墨/ 高铝水泥模压复合材料双极板的特性

采用高铝水泥作为粘结剂, 石墨作为导电填料, 通过室温模压的方法制备了导电复合材料, 拟用于制作质子交换膜燃料电池的双极板。对石墨/ 高铝水泥复合材料双极板的电性能和力学性能的影响因数进行了分析和评价, 并测量了该复合材料双极板的含水量、凝胶毛细孔尺寸分布和氢气渗透性。实验结果表明: 含有60 wt %石墨的石墨/ 高铝水泥模压复合材料双极板的电导率和力学强度基本上可以同时满足质子交换膜燃料电池的使用要求; 并且该复合材料双极板含有凝胶毛细孔, 约具有7 wt %的含水量, 具有自增湿功能; 此外, 氢气渗透率也较低。      

Characterization of a highly selective hydrogen permeable silica membrane

The permeability properties of a new type of silica membrane for the small gas molecules CO₂, CO, Ne, CH₄, He, and H₂ are presented. The new membrane, denoted as Nanosil, has unusually high permeance for H₂, but also allows passage of He and to a smaller extent Ne, while excluding all other molecules. The membrane is formed by the decomposition of a silica precursor (tetraethyl orthosilicate) onto a Vycor glass substrate. Nitrogen physisorption isotherms of the Vycor glass substrate indicate that it is a microporous solid with slit-like pores of 3.6 nm diameter, that remains unchanged after the silica deposition. Atomic force microscopy (AFM) shows that the Vycor substrate is made up of rectangular plate-like elements of size 90 nm × 30 nm. Between the plates are found rectangular features of 4 nm breadth which are likely to be the pore mouths. The deposited silica forms a thin layer on top of these plates so as to erase fine structures and increase the average feature size to 110 nm × 50 nm.     

Studies on the processing of nickel base porous wicks for capillary pumped loop for thermal management of spacecrafts

Nickel base sintered porous wicks have potential application as capillary structure in two-phase heat transfer loops of a heat dissipation system, like capillary pumped loop (CPL) and loop heat pipe (LHP). A porous wick is located inside the evaporator of the CPL system and it transports working fluid in the loop by capillary action.In the present work, experimental trials were carried out to achieve porous wick having high porosity with interconnected pores of average size less than 5 μm, higher aspect ratio (L/D >10) and permeability better than 10 m-Darcy (10^?14 m²). A carbonyl nickel powder (2–7 μm) was used as raw material. Loose carbonyl nickel powders (2–7 μm) were sintered in graphite mould under hydrogen atmosphere at different temperatures in order to optimize porosity, pore size and permeability of the sintered wick. For mechanical and physical properties characterization, samples were cut from sintered rod using EDM wire cut to avoid pore closure. Profile making on the sintered rod is also done by wire EDM. Microstructural characterization as well as the effect of W-EDM on the surface pores was done using Scanning Electron Microscopy (SEM). Surface profile making through W-EDM had shown encouraging result. After optimization of process parameters cylindrical wick (L/D ratio: 10) with porosity of 64%, average pore size of 5 μm and a permeability of 70 m-Darcy could be realized.The present paper explain the details of processing of cylindrical shaped porous wicks through sintering technique and effect of EDM on surface pores characteristic.