莫来石/SiC复相多孔陶瓷的制备及性能研究

用高岭土、Al2O3粉和SiC粉末为原料,活性碳为造孔剂制备莫来石/SiC多孔陶瓷.测定了试样的显气孔率、气孔孔径分布和抗弯强度,并分别用XRD和SEM分析晶相组成和断面显微结构.结果表明:莫来石的理论设计质量的分数小于10%时,莫来石/SiC多孔陶瓷的显气孔率随其设计量的增多而急剧降低;莫来石理论设计量继续增加时,试样显气孔率缓慢降低并趋于稳定.气孔孔径随莫来石设计量的增加而急剧减小.抗弯强度随莫来石设计量的增加而先增大,在莫来石理论设计量为20%时达到最大值,此后逐渐降低.SEM分析结果表明:与其他试样相比,莫来石设计量为40%的试样中存在较多的多孔"微区".     

等静压成型碳化硅多孔陶瓷

介绍了等静压成型碳化硅多孔陶瓷的制备技术,研究了高温结合剂加入量及成型粘合剂的加入量对制品的成型性能、气孔率、孔结构、强度等性能的影响.     

环氧树脂多孔复合材料的制备及性能

以环氧树脂为基体、蓖麻油酸(RA)或二聚蓖麻油酸(DRA)改性的四乙烯五胺(TEPA)(RATEPA/DRATEPA)作为固化剂、水为致孔剂、釉粉为无机填料,通过树脂-水-填料悬浮乳液复合体系聚合法,在室温下合成了环氧树脂多孔材料,采用SEM、压汞仪、电子万能试验机、TGA对多孔材料的形貌、孔径分布、孔隙率、机械性能及热性能进行了表征和测试。结果表明:随着水相质量分数和填料粒径的增大,多孔材料的孔径和孔隙率增大,压缩强度减小;随着固化剂分子量的增大,多孔材料的孔径和孔隙率减小,压缩强度增大。当填料粒径为40μm,固化剂为RATEPA,m(水相)∶m(树脂相)=2∶1时,多孔材料的综合性能最佳,其最可几孔径为3.449μm,孔隙率为21.8%,压缩强度为26.89 MPa。TGA和DTG测试结果表明:环氧树脂多孔材料的热稳定良好,具有耐高温性能,可以在高温条件下应用。     

Fabrication and Properties of Ti3SiC2/SiC Composites

Ti3SiC2/SiC composites were fabricated by reactive hot pressing method. Effects of hot pressing temperature, the content and particle size of SiC on phase composition, densification, mechanical properties and behavior of stress-strain of the composites were investigated. The results showed that ： （ 1 ） Hot-pressing temperature influenced the phase composition of Ti3SiC2/SiC composites. The flexural strength and fracture toughness of composites increased with hot pressing temperature. （2） It became more difficult for the composites to densify when the content of SiC in composites increased. It need be sintered at higher temperature to get denser composite. The flexural strength and fracture toughness of composites increased when the content of SiC added in composites increased. However, when the content of SiC reached 50 wt%, the flexural strength and fracture toughness of composites decreased due to high content of pore in composites. （3） When the content of SiC was same, Ti3SiC2/SiC composites were denser while the particle size of SiC added in composites is 12. 8 μm compared with the composites that the particle size of SiC added is 3 μm. The flexural strength and fracture toughness of composites increased with the increase of particle size of SiC added in composites. （4） Ti3SiC2/SiC composites were non-brittle fracture at room temperature.     

原位反应锆英石结合的多孔SiC陶瓷的制备

以α-SiC粉和c-ZrO2粉为原料,聚乙烯醇缩丁醛(polyvinyl butyral,PVB)为造孔剂,通过干压成型,在空气气氛中无压烧结制备了原位反应锆英石结合的多孔SiC陶瓷.研究了烧结温度对多孔SiC陶瓷的相组成、线膨胀、开口气孔率、孔径分布及压缩强度的影响,并对多孔SiC陶瓷的显微结构进行了分析.结果表明:...     

Fabrication and Properties of Aluminabased Reticulated Porous Ceramics

The primary impregnation slurry was prepared using active alumina(56.25 mass%), kaolin(15 mass%), zirconia(3.75 mass%), deionized water(25 mass%), and extra adding FS(0.2 mass%) and CMC(0.4 mass%). The effects of the active alumina particle size(d_(50)=5.043, 2.934, and 1.629 μm) on the rheology and the thixotropy of the slurry were researched. It was found that the bimodal active α-Al_2O_3(AMA-10) with d_(50)=1.629 μm was optimum. The secondary impregnation slurry was prepared using AMA-10, kaolin and zirconia as the main raw materials. Then the alumina-based reticulated porous ceramics were fabricated by the organic foam impregnation method combined with a secondary vacuum impregnation process. The influence of the AMA-10 content on the properties of the ceramics was studied. The residual stress of the specimens was analyzed by finite element analysis. The results show that the smaller alumina particle size and multimodal distribution are beneficial to the thixotropy of the primary impregnation slurry. The secondary vacuum impregnation technique can significantly improve the mechanical properties, the thermal shock resistance and the residual strength of the alumina-based reticulated porous ceramics. With the decrease of alumina content in the secondary impregnation slurry, the residual stress of the external layer of ceramic reinforcement gradually changes from tensile stress to compressive stress, which effectively inhibits the expansion of the surface crack, and remarkably improves the crushing strength retention ratio of alumina reticulated porous ceramics.     

无压烧结制备SiC密封件的工艺与性能研究

采用无压烧结方法制备了碳化硅密封件样品,讨论了对其性能有较大影响的工艺参数。借助SEM分析手段观察了其显微结构,并测试了其力学性能和体积密度。实验结果表明：以酚醛树脂和淀粉混合物为粘结剂,通过添加1～4w t%炭黑2～4w t%B4C,在2100～2150℃、保温0.5～2h条件下得到了力学性能良好的碳化硅制品。其肖氏硬度达到110,抗折强度350 M Pa,弹性模量300 G Pa,密度最高可达3.12 g/cm 3。     

非晶碳化硅量子点的制备及其光学性质研究

采用脉冲激光烧蚀法,以多晶3C-SiC陶瓷片为靶材,制备了悬浮于去离子水中的非晶SiC纳米颗粒.利用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、傅里叶变换红外吸收光谱(FTIR)、紫外可见吸收光谱(UV-Vis)和光致发光谱(PL)等测试手段对其形貌、结构和光学性质进行了分析.结果表明:这些纳米颗粒由大量的非晶SiC构成,粒径在8～9 nm,光学带隙为3.28 eV;样品表现出较强的光致发光,发光峰位于415 nm处,这主要是由于量子限制效应造成的.     

水基冷冻干燥工艺制备莫来石结合多孔SiC陶瓷

以微米级SiC和纳米级α-Al2O3为原料,经水基冷冻干燥及原位反应烧结工艺制备莫来石结合多孔SiC陶瓷.XRD分析表明多孔陶瓷主相是α-SiC,结合相是莫来石.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3 ～20 μm,小孔孔径峰值为0.5 ～1 μm.体系中SiC固相含量及烧结温度对多孔陶瓷显微结构及性能有显著影响.当SiC固相含量由20vol％增至30vol％时,多孔陶瓷的孔结构由间距为20～ 30 μm、且定向排列的层状结构演变为孔径约为4μm的定向通孔结构.当烧结温度由1200℃升至1500℃时,多孔SiC陶瓷开气孔率由66％下降至64％,抗压缩强度由4.5 MPa升至16 MPa.     

小米基生物形态多孔SiC材料

本文介绍了以小米为原材料,利用生物模板技术法制备小米基生物形态SiC材料.通过热重技术分析了小米向碳模板的转化过程.以SEM、压汞技术和颗粒强度测定仪分析了碳模板与SiC的形貌结构和机械强度.结果表明:以液相渗硅法制备的生物形态SiC能很好的保持碳模板的形貌结构,颗粒破碎强度为10.6 N.溶胶凝胶-碳热还原法制备的SiC能较好保持碳模板的形貌结构,而气相渗硅法制备的SiC与碳模板在微观结构上有很大不同.后两种方法制备的SiC机械强度很差.     

Fabrication of Porous SiC Ceramics with Special Morphologies by Sacrificing Template Method

Sacrificial template technique is widely used in producing porous materials with controlled morphologies and tailored properties. In this paper, unique templates such as filters, carbon nanotube, carbon fiber and silica were used to make porous SiC ceramic with special morphologies. Template derived porous ceramic plates, SiC nano-net, fiber-inverse and bead-inverse porous SiC ceramic were successfully prepared from the preceramic precursor, polymethylsilane (PMS). The synthesis procedures were involved with the infiltration of the templates with appropriate concentration of the preceramic polymer, their curing, pyrolysis and subsequent template removal. The synthesized porous SiC was characterized by SEM, TEM, XRD and BET methods.     

有机泡沫浸渍法制备SiC多孔陶瓷的研究

本实验用酚醛树脂的醇溶液将陶瓷粉料调制成浆料,然后用有机泡沫浸渍工艺浸渍成形,渗硅烧结制得碳化硅多孔陶瓷。实验过程确定了稳定浆料所需添加剂的最佳用量,并分析了渗硅反应的机理。该方法制得的泡沫陶瓷气孔率高、电阻率低、机械强度高。     

氧化粘结法制备SiC微孔陶瓷及性能研究

以SiC为主要原料,以碳黑(C)为造孔剂,利用氧化物粘结法制备了SiC微孔陶瓷.研究了热处理温度和含碳量对SiC微孔陶瓷的相组成、外观形貌、体积密度、气孔率、线变化和重量变化的影响,分析了热处理过程中的物理化学变化.结果表明:随温度升高,SiC的氧化程度增大.1400℃烧后试样的表面平整,呈现出致密的粘结层;1450℃下反应剧烈,试样表面发生烧融.随含C量增加,SiC微孔陶瓷的气孔率增加,有利于O2渗入试样内部发生氧化.材料内部结构网络的构建受O2渗入量及表层SiO2生成量的控制.     

碳化硅/堇青石复相多孔陶瓷的制备及性能研究

采用碳化硅、烧高岭土、氢氧化铝、滑石为主要原料,石墨为造孔剂制备了碳化硅/堇青石复相多孔陶瓷.研究了烧结温度和烧结助剂二氧化铈对碳化硅/堇青石复相多孔陶瓷气孔率和强度的影响,并分别用XRD和SEM分析晶相组成和断面显微结构表明:制备出的SiC多孔陶瓷的主相是SiC,结合相是堇青石与方石英,多孔陶瓷具有相互连通的开孔结构;在1350℃烧结,并保温3h,当造孔剂含量为15％时,碳化硅/堇青石复合多孔陶瓷性能最佳,其气孔率31.80％,相应的弯曲强度为63.74 MPa.在1200℃下,添加不同含量的CeO2,对烧结样品的相组成有影响,能够降低生成堇青石的温度,在CeO2含量为3％的样品中,堇青石的峰最明显,但是过量的氧化铈会抑制了堇青石的生成;随着CeO2加入量的增加,其气孔率和弯曲强度也会随之变化,1200℃下,在CeO2加入量为4％时其弯曲强度最优.但随着CeO2的含量的增加,其气孔率逐渐下降.     

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.     

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.     

Porous SiC Ceramics Derived from Tailored Wood-Based Fiberboards

Specific modification of properties such as porosity and pore size of engineered wood-based source material enables the custom design of porous wood-derived SiC that is produced by carbothermal reduction between the carbonized wood-based material and an infiltrated silica sol. In contrast to bulk wood, the anisotropic shrinkage of the source material is less distinctive and can be controlled. Furthermore, the obtained structural properties of the material are isotropic. Material processing and properties of the wood-derived ceramic material are described in this paper.     

利用水热热压-煅烧法将垃圾灰渣制备成轻质多孔材料

采用水热热压-煅烧法将等离子气化垃圾灰渣制备成轻质多孔保温材料.不同的水热工艺会影响析出晶体的类型,针状透辉石可以连接不同玻璃颗粒,使其在煅烧温度下更好的包裹住气体.同时,煅烧工艺也会明显影响气体的逸出情况.当垃圾灰渣利用率为40％时,采用合适工艺可以制备得到抗压强度为5.31 MPa,密度为0.50g/cm3的多孔材料.     

高体积分数SiC/Al电子封装材料的制备及性能研究

用无压浸渗法制备了体积分数高达70％的碳化硅颗粒增强铝基复合材料,用SEM,XRD对试样进行了形貌和成分分析.测定了复合材料的热膨胀系数及热导率,并和理论模型进行了比较.结果表明:高体积分数SiC/Al复合材料的热膨胀系数为5.68×10-6/K,热导率为155 W/m·K,满足电子封装材料的要求.     

碳纤维长度以及添加量对碳化硅网状多孔陶瓷性能的影响

为提高有机泡沫浸渍法制备的碳化硅网状多孔陶瓷的抗折强度,采用碳纤维对碳化硅网状多孔陶瓷进行增强.研究了添加剂和碳纤维对碳化硅陶瓷浆料流变性能和触变性能的影响以及碳纤维长度和添加量对试样微观结构、气孔率、耐压强度、抗折强度的影响.结果表明:当分散剂-FS20添加量为0.1％(质量分数),增稠剂-CMC添加量为0.1％(质...