Fabrication and Characterization of Dual-Channeled Zirconia Ceramic Scaffold

A novel porous ceramic with a structure containing two three-dimensional (3D) pore channels in a tetragonal zirconia polycrystals (TZP) ceramic was fabricated using a combination of a CNC-machining method and slurry coating process. A graphite scaffold with a single interconnected 3D channel as a template was prepared using CNC machining and lamination. The surfaces of the graphite scaffold were then coated uniformly with the TZP slurry, followed by heat treatment at 900°C for 3 h in air to remove the graphite material completely via thermal oxidation and at 1400°C for 3 h in air to sinter the TZP walls. This process produced a dual-channeled TZP scaffold with an additional 3D channel, which replicated the 3D graphite structure with the pre-existing channel. The fabricated scaffold showed ultra-high porosity (91%), high surface area, and high compressive strength (2.04 MPa), as well as a tightly controlled pore structure.     

以冰为模板制备氧化铝多孔陶瓷及其结构特征

以水玻璃溶液为粘结剂,以冰为造孔模板制备氧化铝多孔陶瓷。采用扫描电镜观测多孔陶瓷的显微结构。结果表明,冰是一种理想的造孔模板,浆体特性对多孔陶瓷结构影响较大,当浆体中相对固相含量增大,多孔陶瓷的孔隙会减小;当浆体粘度降低,易得到片层状与微孔复合结构的多孔陶瓷。     

Novel Method To Optimize the Structure of Reticulated Porous Ceramics

A novel method has been developed for the fabrication of silicon nitride reticulated porous ceramics (RPCs) with regulated structure, using polyurethane sponge as the template. This technique includes two centrifuging steps. In the first stage, the polyurethane sponges are coated with thin slurry through high-speed centrifuging. After the slurry on sponges dried, a high-strength green body without filled cells is obtained. In the second stage, because of improved adhesion between the body and the slurry after the first coating, the body with uniformly thick strut is produced by recoating the as-prepared green body with thixotropic slurry and centrifuging again. The loading content of slurry and the pore diameter of the RPCs body greatly depend on the slurry viscosity in the process of recoating. The strut diameter and pore diameter of the RPCs are effectively optimized by modulating the slurry viscosity.     

Freeform Gelcasting of Porous Tubular Alumina Substrate

The present work demonstrates a new method for fabrication of thin-walled tubular alumina substrate by combining the principles of gelcasting and freeform fabrication. A tube made up of filter paper or organic preform was filled with 4 N nitric acid and dipped in a 55 vol% alumina (average particle size 0.34 μm) slurry containing methylolurea and urea. A thin layer of alumina slurry was gelled on the filter paper tube by in situ polymerization of methylolurea and urea monomers present in the slurry by delivering the acid through the walls of the filter paper tube. The thickness of the alumina tube obtained depended on the dipping time. Alumina tubes with thicknesses in the range 0.7–2 mm were obtained for dipping times in the range 1–8 min. The tubes obtained had good surface finishes and profiles. These tubes were sintered at 1150°C and microstructural observation indicated uniform grain size and pore morphology. A porosity of 40% and an average pore size of 300 nm were obtained.     

Fabrication of porous (Ba,Sr)(Co,Fe)O3-δ (BSCF) ceramics using gelatinization and retrogradation phenomena of starch as pore-forming agent

Porous (Ba,Sr)(Co,Fe)O_3-δ (BSCF) ceramics with high open porosity and good electrical conductivity was fabricated using Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF), which shows a high mixed ionic-electronic conductivity. In general, during the fabrication of porous ceramics by the sacrificial template method using pore former particles, closed pores are easily formed unless sufficient pore former particles are added. In this study, we have devised a method using the gelatinization-retrogradation phenomena of starch for producing a porous body with an excellent percolated pore network structure. By dispersing BSCF and starch in an aqueous slurry (0–50% by weight) and heating, gelatinization of the starch occurred and the starch particles adhered to each other. Furthermore, in order to retain the percolated structure, the water solvent was removed by freeze-drying without heating to obtain a dried green body. The sintering behavior of the porous BSCF bodies prepared under various conditions was characterized by microstructural observations and relative density measurements. By optimizing the process conditions of the gelatinization and retrogradation, a porous body having an open porosity of 48.3%, and with 99% of the total pores open, was obtained. The matrix was also well connected and showed a sufficiently high conductivity which was similar to the porous bodies made by the traditional sacrificial template method.     

基于冻结浆料的分层实体制造法加工陶瓷坯体

提出了一种新型陶瓷增材制造方法,浆料由陶瓷粉末、有机粘结剂和去离子水构成,单层生坯的加工过程包括:铺料、冷冻和激光扫描,层层累积成型后,将冻结状态坯体置于冷冻干燥机中干燥,得到陶瓷生坯;分析了激光加工参数和浆料固含量对于激光扫描过程的影响.结果表明:采用激光扫描图形轮廓的方式,避免了激光辐照对材料内部结构的破坏;通过与冷冻干燥技术的结合,充分保留了片层状的孔隙结构;随着激光能量密度的增大,激光扫描线的宽度和激光切割的深度增大;随着浆料固含量的增加,受陶瓷颗粒对激光能量产生散射作用的影响,激光的切割深度减小.     

Fabrication of bioceramic scaffolds with ordered pore structure by inverse replication of assembled particles

β-Tricalcium phosphate (β-TCP) scaffolds with an ordered pore structure were fabricated by ceramic slip casting using a particle-assembled template. An ordered pore structure is expected to enable uniform and accurate improvement in the topology of the porous structure of scaffolds. Monosized spherical polyethylene particles were self-assembled into an fcc lattice by close-packing with a pyramidal indentation and heat-treated for interparticle necking. β-TCP slurry was cast with this particle array, followed by heat treatments to burn out the particles and sinter the β-TCP frame. The sintered scaffold showed not only an ordered arrangement of uniform pores but also pore interconnection pathways, which faithfully replicated the particle-assembled structure. High porosity, high pore interconnectivity, and structural controllability, as well as high accessibility, were achieved by this process.     

Fabrication of a Highly Porous Bioactive Glass–Ceramic Scaffold with a High Surface Area and Strength

A bioactive glass–ceramic scaffold was fabricated, in which two interlaced three-dimensional (3-D) glass–ceramic walls could serve as active surfaces for the formation of a bond to bone. For its fabrication, a 3-D graphite network acting as a template was prepared using the rapid prototyping method, and then uniformly dip coated with a melt-derived glass slurry. The resultant sample was heat treated at 900° or 1000°C for 5 h to remove the graphite network and densify the glass–ceramic walls. The fabricated sample exhibited an ultra-high porosity (∼95%), high compressive strength (0.2±0.03 MPa), as well as a tightly controlled pore structure. In addition, this sample had a high surface area owing to its unique structure, which was expected to enhance the rate of bone growth.     

Worm-hole structured mesoporous carbon monoliths synthesized with amphiphilic triblock copolymer

In the present work, mesoporous carbon monoliths with worm-hole structure had been synthesized through hydrothermal reaction by using amphiphilic triblock copolymer F127 and P123 as templates and resole as carbon precursor. Synthesis conditions, carbonization temperature and pore structure were studied by Fourier transform infrared, thermogravimetric analysis, transmission electron microscopy and N₂ adsorption–desorption. The results indicated that the ideal pyrolysis temperature of the template is 450 °C. The organic ingredients were almost removed after further carbonized at 600 °C and the mesoporous carbon monoliths with worm-hole structure were obtained. The mesoporous carbon synthesized with P123 as single template exhibited larger pore size (6.6 nm), higher specific surface area (747 m² g^?1), lower pore ratio (45.9 %) in comparison with the mesoporous carbon synthesized with F127 as single template (with the corresponding value of 4.9 nm, 681 m² g^?1, 49.6 %, respectively), and also exhibited wider pore size distribution and lower structure regularity. Moreover, the higher mass ratio of template P123/resole induced similar pore size, larger specific surface area and lower pore ratio at the same synthesizing condition. It was also found that the textural structure of mesoporous carbon was affect by calcination atmosphere.     

Production of porous calcium phosphate (CaP) ceramics with highly elongated pores using carbon-coated polymeric templates

This study reports a new way of enhancing the compressive strength of porous calcium phosphate (CaP) ceramics by creating highly elongated pores. These elongated pores were produced by casting a CaP/camphene slurry into stretched polymeric sponges with a thick carbon coating layer used as a template. The sample produced after sintering at 1250 °C for 3 h showed a highly elongated porous structure with a porosity of 38 ± 1.2 vol%, where elongated pores with a size of 512 ± 96 μm were formed as a replica of the template. In addition, CaP walls with a thickness of 841 ± 239 μm were fully densified without any noticeable defects due to the high CaP content of 40 vol% in the CaP/camphene slurry. The compressive strength of the sample was as high as 21 ± 4.9 MPa when tested parallel to the direction of pore elongation, which is much higher than that (12 ± 2.4 MPa) of the sample tested normal to the direction of pore elongation. The sample also showed good biocompatibility, as assessed by the in vitro cell test using a pre-osteoblast cell line.     

模板法制备多孔炭材料的研究进展

模板法为各种有机和无机纳米材料的可控和定向合成开辟了一条全新的技术途径，近年来已经成为材料制备研究领域引人注目的新方法。本文就迄今为止模板法在制备具有规则结构的多孔炭材料领域的研究动态进行综述，介绍了多孔炭材料的模板法制备、应用前景及其可能的形成机制。     

Novel structure of ceramic tape for multilayer devices

To reduce the content of binders surrounding ceramic powders in a ceramic tape and the residual pore after burnout to a minimum, a ceramic tape with double layers was manufactured. One layer was comprised of only organic binder, which imparted sufficient strength and strong adhesive property to the green tape. The other one was a ceramic layer with a very small amount of binder. The binder content of the slurry for ceramic layer was less than 2 wt%, which could lower the viscosity, make the slurry well dispersed and considerably increase solid loading in the slurry. This higher solid loading led to higher green tape density, higher fired density of the product. The two-layer ceramic tape showed much better qualities than a common (or conventional) green tape especially in microstructure, laminatablilty, and tape density. In the multilayer structure made of the two-layer ceramic tape, the binder layer completely disappeared after binder-burnout and no defects from the two-layer structure were observed.     

ZSM-5的合成及应用进展

ZSM-5由于具有特殊的孔结构和物化性质而被广泛应用于化工各个领域。介绍了ZSM-5的合成方法及晶化机理,合成方法包括模板剂合成法（有机胺法、无机铵及醇类法）、微波合成法、无模板剂合成法,讨论了各种合成方法的优点和缺点,指出无模板剂的绿色合成方法是未来合成分子筛的重要方向。介绍了近年来ZSM-5在电化学、生物质、环境保护等领域的最新应用进展,为开发ZSM-5新的合成方法和利用途径提供参考。     

利用简单模板制备多孔二氧化硅

以简单有机模板为致孔剂、正硅酸乙酯(TEOS)为硅源制备了多孔SiO2,考察了模板剂加入量对样品比表面和孔容的影响,测定了样品的比表面和孔结构,提出了简单有机模板对多孔SiO2的致孔机理,并与以碱性硅溶胶为硅源对比,验证了该机理. 结果表明,简单有机模板添加量为模板剂/TOES=0.3 mg/mL时,样品比表面积可提高至650 m2/g以上,孔容大于1.0 mL/g,孔道为无规则结构. 该多孔结构的产生很可能是因为简单有机模板和TEOS的聚合物发生分子级混合,从而在凝胶和煅烧过程中使样品中产生了丰富的孔道.     

Enhancing the thermal insulating properties of lanthanum zirconate porous ceramics via pore structure tailoring

The potentially useful role of lanthanum zirconate (La₂Zr₂O₇, LZO) porous bulk ceramics has been rarely explored thus far, much less the optimisation of its pore structure. In this study, LZO porous ceramics were successfully fabricated using a tert-butyl alcohol (TBA)-based gelcasting method, and the pore structures were tailored by varying the initial solid loading of the slurry. The as-prepared ceramics exhibited an interconnected pore structure with high porosity (67.9 %–84.2 %), low thermal conductivity (0.083–0.207 W/(m·K)), and relatively high compressive strength (1.56–7.89 MPa). The LZO porous ceramics with porosity of 84.2 % showed thermal conductivity as low as 0.083 W/(m·K) at room temperature and 0.141 W/(m·K) at 1200 °C, which is much lower than the counterparts fabricated from particle-stabilized foams owing to its unique pore structure with a smaller size, exhibiting better thermal insulating performance.     

Biomimetic Synthesis and Characterization of Mesoporous Titanium Dioxide

Mesoporous titanium dioxide (TiO₂) with a pore size range from 5–7 nm was synthesized by a sol‐gel method using biosurfactant phosphatidylcholines as an organic template. Titanium tetrabutoxide (TBOT) was used as the precursor. A very fine mesoporous structure formed in the particle was maintained after a heat treatment at 700 °C. Low‐angle X‐ray powder diffraction (XRD) and a pore size distribution curve revealed the existence of the mesoporous structure. Transmission Electron Microscopy (TEM) and N₂ adsorption–desorption isotherms were utilized for further characterization. A significant red shift in the UV‐VIS spectrum of the porous material was observed, which could be explained by the energy band theory. The results confirmed the synthesis of mesoporous TiO₂.     

微观孔隙结构与聚合物匹配性研究

大庆油田采油五厂在总结其动态变化特征及调整方法时发现,油层发育相似的井聚驱效果、增产措施效果会存在一定的差异,从杏十三区聚驱工业区沉积相带图看,大面积发育河道的层位,孔隙结构存在较大差异,因此针对孔隙结构进行室内入注能力的研究,通过分析聚合物与孔隙结构的匹配关系,结合室内研究成果,确定了微观空隙结构与聚合物的匹配模板.     

Ordered mesoporous carbon prepared from triblock copolymer/novolac composites

Ordered mesoporous carbon is synthesized by the organic–organic self-assembly method with novolac as carbon precursor and two kinds of triblock copolymers (Pluronic F127 and P123) as template. The hexagonal structure and a worm-hole structure are observed by TEM. The carbonization temperature is determined by TG and FT-IR. Characterization of physical properties of mesoporous carbon is executed by N₂ absorption–desorption isotherms and XRD. The mass ratios of carbon precursor/template affect the textural properties of mesoporous carbon. The mesoporous carbon with F127/PF of 1/1 has lager surface area (670 m² g^?1), pore size (3.2 nm), pore volume (0.40 cm³ g^?1), smaller microporous surface area (368 m² g^?1) and wall thickness (3.7 nm) compare to that with F127/PF of 0.5/1 (576 m² g^?1, 2.7 nm, 0.29 cm³ g^?1, 409 m² g^?1 and 4.3 nm, respectively). The mesoporous carbon prepared by carbonization at high temperature (700 °C) exhibits lager surface area, lower pore size and pore volume than the corresponding one obtained at 500 °C. The structure and order of the resulting materials are notably affected with types of templates. The mesoporous carbon with P123 as template exhibits worm-hole structure compare to that with F127 as template with hexagonal structure. In general, the pore size of mesoporous carbon with novolac as precursor is smaller than that with resorcinol–formaldehyde as precursor.     

有序介孔碳材料的模板化构筑及水处理应用研究

介孔碳材料是指孔径介于2 nm-50 nm的一类多孔碳材料。有序介孔碳材料，具有比表面积高、孔道结构规则有序、孔径分布狭窄、孔径大小可调控、表面易于修饰等结构特点和高机械强度、强吸附能力、化学惰性等性能特点，在诸多领域得到了广泛应用，特别是其作为新型吸附剂在水处理领域具有广阔的发展前景。有序介孔炭材料的制备方法主要有硬模板法和软模板法。模板和碳源的选择是控制有序介孔碳材料结构和性能的关键因素。本文从有序介孔硅、天然矿物、MOFs材料、嵌段共聚物等不同模板的角度对有序介孔碳、多级有序微/介孔碳、多级有序大/介孔碳的制备方法进行综述，并对有序介孔碳材料在水处理领域的应用进行简单介绍。     

Supercritical Fluid Extraction of a Novel Template from Mesoporous Zirconia and the Effect on Porous Structure

Mesoporous zirconia was synthesized by a new and simple method. Zirconium n-propoxide was used as the zirconium source. A small, inexpensive nonsurfactant, triethanolamine, was used as the template. The template was removed by thermal treatment in air and supercritical fluid extraction using CO₂. The structure of the resulting materials was characterized by X-ray diffraction, transmission electron microscopy, and N₂ adsorption-desorption analyses. The materials are found to have narrowly distributed average pore diameters and wormhole-like pore channels. However, higher surface area and larger pore volume are exhibited after supercritical fluid extraction with CO₂. The removal of the template by thermal treatment also leads to condensation and mild shrinkage of the zirconia framework.