造孔剂法制备多孔生物玻璃陶瓷的工艺研究

通过造孔剂法,以溶胶-凝胶法制备的生物玻璃58S和熔融法制备的生物玻璃45S5为原料,以NH4 HCO3与淀粉的混合物为造孔剂制备生物玻璃陶瓷.利用XRD和SEM等材料分析测试手段研究了烧成温度、造孔剂添加量、成型压力及45S5的用量对多孔材料显微结构、表面形貌、抗折强度的影响.结果表明:在成型压力20 MPa,造孔剂含量60％,烧成温度800℃及45S5的加入量10％的工艺参数下,制备出抗折强度达到4.5 MPa,孔隙率达到68.74％的珊瑚状结构的多孔生物玻璃陶瓷材料.     

酚醛树脂基多孔炭材料制备的研究

以酚醛树脂为炭前驱体、聚乙烯醇缩丁醛(PVB)为造孔剂,采用聚合物共混炭化法制备了多孔炭材料,考察了造孔剂PVB的含量、炭化温度和炭化时间对多孔炭材料比表面积和孔结构的影响.结果表明,在造孔剂PVB的含量为40%、炭化温度为700℃、炭化时间为1.0 h的条件下,可制得BET比表面积为540.4 m2·g-1、孔容为0.37 cm3·g-1、平均孔径为7.298 nm的多孔炭.     

造孔剂含量对多孔预制体孔隙率的影响

本文采用无压浸渗法制备了SiC/Al复合材料,研究了造孔剂含量对多孔预制体孔隙率的影响。结果表明:随着造孔剂加入量的增加,孔隙率增加;但当造孔剂含量大于20%时,多孔预制体的孔隙率趋于48%左右。     

添加造孔剂法制备多孔陶瓷及其强度与孔径控制

采用添加造孔剂法制备了多孔陶瓷.系统地研究了造孔剂种类、粘结剂含量、球磨时间、烧结制度对多孔陶瓷强度及开口孔隙率的影响,以及钠长石含量对多孔陶瓷孔径分布的影响.结果表明,不同造孔剂对多孔陶瓷强度的影响不同.并且在球磨时间为12h之前,随着球磨时间的延长,多孔陶瓷的强度呈增加趋势.而随着钠长石含量的增加,多孔陶瓷的孔径呈减小的趋势.     

影响多孔玻璃孔结构的因素

研究表明,利用填充法制备的多孔玻璃的孔参数(气孔率、孔径分布)可进行设计与控制,多孔玻璃的气孔率和孔径分布主要取决于成孔剂的体积比及其颗粒分布,前者与后者之间的偏差取决于生坯制备及烧结过程.     

羟基磷灰石多孔陶瓷的制备和性能

本工作采用造孔剂（ＰＦＡ）干压工艺制备羟基磷灰石多孔陶瓷。通过两种造孔剂制得的多孔羟基磷灰石陶瓷性能的对比,发现两种造孔剂可制得多孔羟基磷灰石陶瓷。并借助ＳＥＭ、压汞仪等仪器和设备,对多孔体的性能进行了测试,讨论了造孔剂粒径、添加量及形状对多孔体性能的影响,结果表明：采用碳粉作造孔剂制得的多孔体具有较高的强度,而采用聚甲基丙烯酸甲酯（ＰＭＭＡ）作造孔剂制得的多孔体孔径的可控性高。     

不同造孔剂对CA6-MA多孔材料性能的影响

以等离子熔融还原技术提取硅钛合金后的尾渣(<0.088 mm)和工业氧化铝(D50=8.79 μm)为原料,选取锯末、玉米淀粉和炭黑作为造孔剂,采用浇注成型工艺,在1550 ℃温度下烧成制得了六铝酸钙-镁铝尖晶石多孔材料,对多孔材料的常温物理性能和成孔机理做了对比研究.采用15%锯末和30%玉米淀粉复合造孔剂可以制备出具备双峰孔径分布、显气孔率70%、耐压强度1.6 MPa的CA6-MA多孔材料.     

多孔低介电氧化硅陶瓷材料的制备

采用氧化硅为原料,木屑作为造孔剂制备了多孔的氧化硅陶瓷材料。借助于气孔率测试、抗弯强度测试、介电性能测试和SEM测试手段分析了造孔剂和烧结助剂的添加量对材料性能的影响。结果表明:加入BN作为添加剂烧成的氧化硅抗弯强度最大可达到14.80MPa。加入木屑作为造孔剂制备的陶瓷可以形成明显的气孔,气孔率最高可达到48.40%,介电常数最低可以达到3.0。     

硅质材料的粒度与粒度分布对过滤器孔特性的影响

多孔陶瓷的孔特性(包括气孔率、孔径及分布、孔结构 )是影响其性能和功能的重要参数, 而在添加造孔剂法制备多孔陶瓷中, 各工艺因素都会影响到制品的孔特性.因此, 系统研究各工艺因素对多孔陶瓷的孔特性的影响, 将有助于找出解决办法, 精确控制多孔陶瓷孔特性, 从而制备出性能优良的多孔陶瓷.通过实验研究了硅质材料的粒度及粒度分布对多孔陶瓷过虑器孔特性的影响, 并提出了一些控制多孔陶瓷孔特性的有效措施.研究表明, 随着骨料粒径的减少, 过滤器的吸水率和气孔率增大, 随着骨料粒度分布范围变宽, 过滤器的吸水率和气孔率下降, 减少骨料粒度分布范围, 将形成较均匀的气孔结构.     

模板-滤取法制备UHMWPE多孔材料及其孔道结构

采用模板-滤取法制备超高分子量聚乙烯(UHMWPE)多孔材料,在NaCl作为造孔剂的基础上加入蔗糖作为助溶剂来调整和控制孔道结构,通过孔道结构的形貌观察和孔隙率的计算分析得出,蔗糖在超高分子量聚乙烯多孔材料孔道结构的形成过程中起到了管道连通作用,促进造孔剂NaCl的溶解,提高了孔隙率,改善了孔道结构。     

氧化铈多孔陶瓷的制备

本文以Ce(NO3)3.6H2O为原料,以氨水为沉淀剂,采用水热法制备出氧化铈粉体,并以淀粉为造孔剂制备出了氧化铈多孔陶瓷。利用X射线衍射仪、扫描电子显微镜对氧化铈粉体及多孔陶瓷其进行了表征。结果表明氧化铈的烧结温度为1450℃左右,以淀粉占氧化铈质量的40%制备出的多孔陶瓷气孔形状规则,分布均匀。     

Macro and meso porous polymeric materials from miscible polysulfone/polyimide blends by chemical decomposition of polyimides

Novel macro and meso porous polysulfone materials were prepared from miscible blends of polysulfones with a phenylindane containing polyimide by selective chemical decomposition of the polyimide phase using a dilute hydrazine or tetraammonium hydroxide solution in methanol. It was found that the pore size of the material is affected by the backbone structure of the polysulfone selected. The compatibility between the polysulfones and the polyimide is influenced by the polysulfone structure. This in turn affects the pore size and the pore size distribution of the final porous material. Polyether sulfone was found to form most compatible blends that in turn leads to a porous material with the smallest pore size, a meso porous material. The meso porous polyether sulfones are transparent films, with uniform pore sizes in the range of 30 nm, while bisphenol A polysulfone based porous materials are opaque with pore sizes in the range of 200 nm.     

用原子力显微镜研究聚乙烯醇分离膜的结构

分别用饱和硫酸钠/氢氧化钠溶液和丙酮作为凝固浴制备聚乙烯醇（PVA）分离膜,在原子力显微镜（AFM）下观测发现：前者膜的表面结构与致密膜相似,后者则呈现出平均孔径为53nm的多孔膜结构,但二者都具有球粒状结构.实验证实,选用适当的凝固浴才能制备出聚乙烯醇多孔膜.     

Effects of the Use of Pore Formers on Performance of an Anode Supported Solid Oxide Fuel Cell

The effects of amount of pore former used to produce porosity in the anode of an anode supported planar solid oxide fuel cell were examined. The pore-forming material utilized was rice starch. The reduction rate of the anode material was measured by Thermogravimetric analysis to qualitatively characterize the gas transport within the porous anode materials. Fuel cells with varying amounts of porosity produced by using rice starch as a pore former were tested. The performance of the fuel cell was the greatest with an optimum amount of pore former used to create porosity in the anode. This optimum is believed to be related to a trade off between increasing gas diffusion to the active three-phase boundary region of the anode and the loss of performance because of the replacement of active three-phase boundary regions of the anode with porosity.     

Reactive melt infiltrated Cf/SiC composites with robust matrix derived from novel engineered pyrolytic carbon structure

Needle-punched C_f/SiC composites were fabricated by a novel pore tuned reactive melt infiltration (RMI) process. The novel hierarchically porous carbon structure in the fiber preform with the porosity well open to liquid silicon was engineered by impregnation of phenolic resin with addition of a pore former. Neither residual bulk carbon nor residual bulk silicon is detected in the matrix of the C_f/SiC composites prepared by the pore tuned RMI, indicating that a robust matrix with homogenous SiC can be formed. The composite prepared by the pore tuned RMI exhibits a tensile strength of 159±5 MPa, which is 46% higher than that without addition of pore former.     

烧结制度及造孔剂用量对粉煤灰基多孔陶瓷膜支撑体性能的影响

以粉煤灰为原料,采用挤压成型和固态粒子烧结法制备管状粉煤灰基多孔陶瓷膜支撑体.采用TG-DSC技术对粉煤灰进行了热分析,采用SEM和XRD技术对样品的微观结构及物相组成进行了分析,并测定了样品的开孔率、抗压强度及空气渗透速率等性能指标.研究了烧结温度、保温时间和造孔剂添加量对支撑体性能的影响.结果表明:支撑体晶相组成主要为赤铁矿、红柱石和石英;烧结温度为1000 ℃,保温2 h,仅添加1%的粘结剂,不添加造孔剂的条件下制备出的管状支撑体综合性能最优,此时的支撑体孔隙率为44.95%,抗压强度为8.92 MPa,空气渗透速率为2.57×104 m3·h-1·m-2·MPa-1.     

Gas permeability and mechanical properties of porous alumina ceramics with unidirectionally aligned pores

Porous alumina ceramics having unidirectionally aligned cylindrical pores were prepared by extrusion method and compared with porous ceramics having randomly distributed pores prepared by conventional method, and their gas permeability and mechanical properties were investigated. SEM micrographs of the porous alumina ceramics prepared by the extrusion method using nylon fibers as the pore former showed excellent orientation of cylindrical pores. The bending strength and Weibull modulus of the extruded porous alumina ceramics with 39% porosity were 156 MPa and 17, respectively. These mechanical properties of extruded samples were higher than those of the conventional porous alumina ceramics. The strength decreased from 156 to 106 MPa with increasing pore size from 8.5 to 38 μm. The gas permeability of the extrusion samples is higher than that of the conventional samples and increased with increasing of porosity and pore size.     

Fabrication and characterisation of cellular alumina articles produced via radiation curable dispersions

A general and versatile method for the production of cellular materials from radiation curable solvent-free colloidal ceramic dispersions containing pore formers has been developed. By this technique cellular ceramic articles with a precisely controlled porosity, cell size and shape are obtained for compositions containing solid pore formers. Monolithic bulk samples are obtained by thermal curing, whereas thin films and multi-layered articles are advantageously produced by UV curing. In this work the influence of three different spherical pore former types, PE, PS and PMMA, on the processing and final properties of the porous materials using alumina as model material is studied. The effect of pore former type and concentration on rheology, curing behaviour, debinding and sintering steps as well as thermal conductivity and mechanical strength of the sintered cellular materials is presented. It is also shown that the choice of pore former type modifies the sintering behaviour and resulting properties.     

Porous carbon material based on petroleum pitch

The samples of granulated (2–4 mm) porous carbon material with unimodal and bimodal poresize distributions were prepared. The sample with a unimodal porous structure was prepared via the mixing of soot and petroleum pitch followed by carbonization (the first stage). At the second stage, the carbon material obtained was ground to a particle size smaller than 0.2 mm, mixed with petroleum pitch, and also subjected to carbonization. The porous structures of these materials were studied by scanning electron microscopy and mercury porosimetry. It was established that the predominant pore size (20–1000 nm) of the samples with the unimodal structure depends on the used soot grade. At the second stage of the process, a considerable volume of pores in a range of 4–12 μm is formed in the production of bidisperse material. As compared with a sample with the monodisperse structure, porous carbon material with a bimodal distribution of pores was characterized by a lower crushing strength of granules and comparable specific surface areas, total pore volumes, and ash contents.