多孔陶瓷分离膜支撑体的制备研究

采用氧化铝为主要原料制备出多孔陶瓷分离膜支撑体,对原料粉体做了TG/DSC曲线分析,研究了支撑体的烧结温度对收缩率的影响及烧结温度、保温时间和原料粉体粒径对孔结构、孔径的影响,造孔剂用量对孔隙率的影响。结果表明：在烧结温度为1200℃,保温时间4h,控制造孔剂用量大于20%时,制备出孔径分布均匀,孔隙率大于50%,符合透水要求的多孔陶瓷分离膜支撑体。     

水基冷冻干燥工艺制备层状结构多孔SiC陶瓷

以微米级SiC粉体为原料,利用冷冻干燥和原位反应烧结制备了具有层状孔道结构的SiC多孔陶瓷.XRD分析表明多孔陶瓷的主相是α-SiC,结合相是方石英;SEM观察到多孔陶瓷具有相互连通的开孔结构;多孔SiC陶瓷的总孔隙率和开孔隙率随固相含量和烧结温度的增加而下降.多孔陶瓷的孔径分布呈现双峰分布特点,大孔孔径峰值介于20～80 μm,小孔孔径峰值为0.5～0.9 μm.在原位反应烧结过程中,在1100℃以上SiC开始发生氧化形成SiO2结合的多孔SiC陶瓷,显著提高了陶瓷的压缩强度.随着烧结温度从1000℃提高到1500℃,固相含量为30vol%的多孔SiC陶瓷开孔率从68.9%下降到61.8%,压缩强度由5.5 MPa升至25.5 MPa.     

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.     

氮化钛多孔陶瓷的制备、孔隙结构调控及其力学、导电性能

采用凝胶注模成型工艺制备TiN多孔陶瓷,研究了固含量、烧结温度对TiN多孔陶瓷物相组成、微观结构、孔隙率和孔径分布的影响,以及Ti N多孔陶瓷孔隙结构与其力学、电学性能的关联。结果表明:随着固含量和烧结温度的升高,TiN多孔陶瓷孔隙分布均匀,孔径尺寸和孔隙率缓慢下降,其开气孔率变化范围为41.8%~60.0%。随着孔隙率的降低及烧结温度的升高,TiN多孔陶瓷抗弯强度及电导率分别由14.2 MPa和7.9×10~3 S/m逐渐增大到34.6 MPa和23.1×10~3 S/m,这是由于Y_2TiO_5液相的产生,促进了晶粒生长及孔壁连接。     

烧成温度对多孔SiC陶瓷管性能的影响

以SiC为骨料,添加低共熔混合物烧结促进剂,煤粉作为造孔剂,在不同的温度下烧成制备多孔陶瓷管.考察了烧成温度对多孔SiC陶瓷管的孔隙率、气体渗透通量、孔径分布以及抗弯强度等性能的影响,并通过SEM对其结构形貌进行了表征.结果表明:随着烧成温度的提高,孔隙率、气体通量及抗弯强度下降,孔径分布变宽.     

工艺参数对石英质多孔材料孔性能的影响

以长江沿岸低品位石英砂为主要原料,采用真空烧结制备了石英质多孔材料。通过实验分析发现:随烧结温度的升高、水料比的增大或发泡剂含量的增加,多孔材料的气孔率增大,抗压强度降低;而随着保温时间的延长,多孔材料的气孔率降低,抗压强度升高。通过优化得出最佳配比为:石英砂60 wt%、高岭土30 wt%、助烧剂9.6 wt%、发泡剂0.4 wt%。按这一最佳配比配料,在水料比为0.9的条件下球磨2 h制浆发泡,而后在1175°C烧结1 h,可以制备得到性能较佳的石英质多孔材料。     

高温烟气过滤SiC多孔陶瓷孔隙率及烧结工艺研究

主要研究了碳化硅多孔陶瓷孔隙率的影响因素以及烧结工艺对碳化硅多孔陶瓷材料性能的影响。碳化硅多孔陶瓷孔隙率的大小直接影响其烟气的过滤效率,通过研究碳化硅骨料的粒径,碳化硅的含量以及造孔剂含量对孔隙率和孔径大小的影响因素,实现了对碳化硅多孔陶瓷的孔隙率大小的有效控制。同时对碳化硅多孔陶瓷的烧结工艺中的烧成气氛和烧成温度进行了研究,研究发现,在弱氧化气氛下,烧成温度为1330℃时制备的碳化硅多孔陶瓷具有较高的孔隙率和较为优异的力学性能。     

泥料含水量对粉煤灰陶瓷膜支撑体性能的影响

泥料含水量是陶瓷生产中的重要参数,会影响陶瓷的收缩率、抗弯强度等性能。以电厂粉煤灰为主要原材料、糊精为造孔剂、羧甲基纤维素为黏结剂,采用挤出成型法制备了管状多孔陶瓷膜支撑体。通过控制陶瓷泥料用水量和烧结保温时间制备了不同支撑体,并对支撑体进行性能表征,考察了泥料含水量和烧结保温时间对支撑体微观结构、收缩率、孔隙率、孔径以及机械强度等性能的影响。结果表明：在水/固质量比质量为0.19时,1 150℃保温烧结2 h获得孔隙率40.5%、抗弯强度23.6 MPa、平均孔径0.41μm的支撑体。制备的支撑体应用于脱硫废水微滤处理,固体悬浮物截留率99.98%。为制备低成本粉煤灰陶瓷膜支撑体提供研究基础,有利于膜法水处理的扩大化应用。     

α/β相变对多孔氮化硅陶瓷介电性能的影响

采用反应烧结工艺,通过添加硬脂酸,制备孔径为0.8mm,孔隙率在55%左右的具有宏观球形孔的低密度多孔氯化硅陶瓷,研究了α/β相变对多孔氮化硅陶瓷介电性能的影响.通过调节氮化温度和时间,可得到具有不同β相相对含量(质量分数,下同)的多晶氮化硅陶瓷.结果表明:氮化温度高于1 400℃时发生α/β相变,随着氮化温度的提高和...     

无机盐/石英基复合相变储能材料多孔陶瓷基体的制备

以石英为骨料,钾长石为高温粘结剂,木炭为造孔剂制备无机盐/石英基复合相变储能材料用的微米孔石英多孔陶瓷基体,采用正交实验法系统研究了骨料颗粒粒度、造孔剂粒度、造孔剂含量、高温粘结剂含量及烧成温度对石英多孔陶瓷的显气孔率和抗折强度的影响.研究结果表明,影响石英多孔陶瓷抗折强度的最主要因素是长石含量,其次是骨料粒度和造孔剂粒度;影响石英多孔陶瓷显气孔率的主要因素是造孔剂含量.制备微米孔石英多孔陶瓷的优化配方和工艺是:石英、木炭和长石均过325目筛,三者质量比为7:2:1,烧成温度为1270f,保温时间为1h.该陶瓷具有以下优良的性能:显气孔率为55.12％,体积密度为1.14 g,/cm3,抗折强度为3.14 MPa,抗压强度为7.12 MPa,平均孔径为13.87 μm且孔径分布范围较窄,96％的气孔孔径在9～21 μm之间.     

梯度多孔载Ag羟基磷灰石陶瓷的制备和性能研究

本文采用添加造孔剂法制备孔隙呈现梯度分布的多孔载Ag羟基磷灰石(Ag-HA)陶瓷.研究了造孔剂分布、烧结温度和载Ag含量对梯度多孔Ag-HA陶瓷孔隙度的影响.分析了烧结产物的物相组成和微观形貌,测量了烧结后梯度多孔Ag-HA陶瓷的压缩性能和抗菌性能.研究结果表明:随着中间层造孔剂含量增加,梯度多孔Ag-HA陶瓷的孔隙度...     

Porosity control of porous silicon carbide ceramics

Porous SiC ceramics were fabricated by the carbothermal reduction of polysiloxane-derived SiOC containing polymer microbeads followed by sintering. The effect of the SiC powder:polysiloxane-derived SiC (SiC:PDSiC) ratio on the porosity and flexural strength of the porous SiC ceramics were investigated. The porosity generally increased with decreasing SiC:PDSiC ratio when sintered at the same temperature. It was possible to control the porosity of porous SiC ceramics within a range of 32–64% by adjusting the sintering temperature and SiC:PDSiC ratio while keeping the sacrificial template content to 50 vol%.The flexural strengths generally decreased with increasing porosity at the same SiC:PDSiC ratio. However, a SiC:PDSiC ratio of 9:1 and a sintering temperature of 1750 °C resulted in excellent strength of 57 MPa at 50% porosity. Judicious selection of the sintering temperature and SiC:PDSiC ratio is an efficient way of controlling the porosity and strength of porous SiC ceramics.     

不同助烧结剂及造孔剂对SiC多孔陶瓷的影响

采用真空烧结方法制备了SiC多孔陶瓷，研究了不同助烧结剂Al2O3-Y2O3、Si以及不同造孔剂丙烯酰胺聚合物、羧甲基纤维素（CMC）对SiC多孔陶瓷形貌和气孔率的影响。结果表明：与Si相比较，Al2O3-Y2O3更有利于促进SiC的烧结；以Al2O3-Y2O3为助烧结剂的试样比以Si为助烧结剂的试样具有较高的气孔率。     

Preparation of high strength lamellar porous calcium silicate ceramics by directional freeze casting

In this study, porous calcium silicate (CS) ceramics with oriented arrangement of lamellar macropore structure were prepared by directional freeze casting method. The lamellar macropores were connected by the micropores on the pore wall, which had good pore interconnectivity. The effects of solid loading of the slurry, freezing temperature, sintering additive content, and sintering temperature on the microstructures and compressive strength of the synthesized porous materials were investigated systematically. The results showed that with the increase of solid loading (≤20 vol%) and sintering additive content, the sizes of lamellar pores and pore walls increased gradually, the open porosity decreased and the compressive strength increased. The sintering temperature had little effect on the pore size of the ceramics, but increasing the sintering temperature (≤1050 °C) promoted the densification of the pore wall, reduced the porosity, and improved the strength. The decrease of freezing temperature had little effect on porosity, but it reduced the size of lamellar pore and pore wall, so as to improve the strength. Finally, porous CS ceramics with lamellar macropores of about 300–600 μm and 2–10 μm micropores on the pore wall were obtained. The porous CS ceramics had high pore interconnectivity, an open porosity of 66.25% and a compressive strength of 5.47 MPa, which was expected to be used in bone tissue engineering.     

不同铝源对SiC/堇青石复相多孔陶瓷的制备及性能影响

以碳化硅、氮化铝、层析氧化铝、氢氧化铝、氟化铝、滑石为主要原料,石墨为造孔剂通过原位反应烧结技术制备碳化硅/堇青石复相多孔陶瓷.研究了含铝化合物种类、烧结温度、石墨含量对SiC/堇青石复相多孔陶瓷相组成、微观结构、气孔率和抗折强度的影响,同时对S0组在1200℃烧结温度下制得的SiC/堇青石复合多孔陶瓷的孔径分布进行了测试分析.结果表明:以AlN为铝源在1200℃下烧结,石墨含量在15％时,堇青石结合SiC多孔陶瓷的抗弯强度和气孔率两项综合性能达到最优,气孔率为31.99％,相应的弯曲强度86.20 MPa.S0组的平均孔径大小在3.0191 μm.     

SiC多孔陶瓷预成形坯的制备

本文采用真空烧结方法制备SiC多孔陶瓷预成形坯,研究了不同助烧结剂Al2O3-Y2O3、Si、Co和高岭土以及造孔剂羧甲基纤维素(CMC)含量对SiC多孔陶瓷预成形坯气孔率和形貌的影响。结果表明,多元助烧剂Al2O3-Y2O3有利于降低烧结温度和形成液相烧结,并有利于提高SiC多孔陶瓷的孔结构稳定性;羧甲基纤维素含量对烧结预成形坯气孔率和体积密度的影响较大,随着造孔剂CMC含量的增加,SiC多孔陶瓷的气孔率也相应地增加,其体积密度相应减少。     

Porous YSZ Ceramics Reinforced by Different Kinds of Fibers

Porous YSZ ceramics reinforced by different fibers were prepared by gel‐casting with 15% solid content and pressureless sintering. The four kinds of fibers (mullite, aluminosilicate, Al₂O₃, and YSZ fibers) were added into the YSZ ceramics with the same 10% vol content. After sintered at 1500°C for 2 h, aluminosilicate and mullite fibers could not be found in the samples of porous YSZ ceramics, which showed they reacted with YSZ ceramics at high temperature, while YSZ and Al₂O₃ fibers still kept perfect after sintering. Furthermore, the influences of fiber content, sintering temperature, porosity of matrix materials on compressive strength and porosity of the porous YSZ ceramics were studied. The results showed that Al₂O₃ fiber showed more obvious reinforcing effect than YSZ fiber on porous YSZ ceramics. The fiber‐reinforcing effects depend on fiber content, sintering temperature, and porosity of matrix materials. The fiber addition can improve the shrinkage behavior of porous ceramics during sintering and strengthen the skeleton of porous ceramics.     

多孔碳化硅陶瓷的原位氧化反应制备及其性能

以SiC为陶瓷骨料,Al2O3作为添加剂,通过原位氧化反应制备了Sic多孔陶瓷,并对其氧化反应特性及性能进行了研究.结果表明:在1 300～1 500℃,随烧结温度的升高,SiC的氧化程度增加,SiC多孔陶瓷的强度逐渐增加,但开口孔隙率有所降低.莫来石相在1 500℃开始生成·当烧结温度升高到1 550℃时,莫来石大量生成,得到了孔结构相互贯通且颈部发育良好的莫来石结合SiC多孔陶瓷;由于在SiC颗粒表面上覆盖了致密的莫来石层,SiC的氧化受到抑制,开口孔隙率因而升高,SiC多孔陶瓷的强度因莫来石的大量生成而增加.由平均粒径为5.0um的SiC,并添加20%(质量分数)Al2O3,经1 550℃烧结2h制备的SiC多孔陶瓷具有良好的性能,其抗弯强度为158.7MPa、开口孔隙率为27.7%.     

Low sintering shrinkage porous mullite ceramics with high strength and low thermal conductivity via foam-gelcasting

Excessive sintering shrinkage leads to severe deformation and cracking, affecting the microstructure and properties of porous ceramics. Therefore, reducing sintering shrinkage and achieving near-net-size forming is one of the effective ways to prepare high-performance porous ceramics. Herein, low-shrinkage porous mullite ceramics were prepared by foam-gelcasting using kyanite as raw material and aluminum fluoride (AlF₃) as additive, through volume expansion from phase transition and gas generated from the reaction. The effects of AlF₃ content on the shrinkage, porosity, compressive strength, and thermal conductivity of mullite-based porous ceramics were investigated. The results showed that with the increase of content, the sintering shrinkage decreased, the porosity increased, and mullite whiskers were produced. Porous mullite ceramics with 30 wt% AlF₃ content exhibited a whisker structure with the lowest shrinkage of 3.5%, porosity of 85.2%, compressive strength of 3.06 ± 0.51 MPa, and thermal conductivity of 0.23 W/(m·K) at room temperature. The temperature difference between the front and back sides of the sample reached 710°C under high temperature fire resistance test. The low sintering shrinkage preparation process effectively reduces the subsequent processing cost, which is significant for the preparation of high-performance porous ceramics.