ZrO2粉料在Al2O3-SiC纳米复合陶瓷中的作用

采用不同粒径的ZrO₂粉料增强增韧Al₂O₃-SiC纳米复合陶瓷，利用无压烧结制备出了致密的Al₂O₃-ZrO₂(3Y)-SiC纳米复合陶瓷.对不同粒径的ZrO₂粉料在Al₂O₃-SiC纳米复合陶瓷中所起的作用进行了研究，结论为ZrO2粉料的粒径是影响烧结温度的重要因素，添加纳米级的ZrO₂可以降低烧结温度100 ℃以上.断裂表面的SEM图像表明：穿晶断裂是Al₂O₃-ZrO₂-SiC纳米复合陶瓷的主要断裂模式，这是所制备纳米复相陶瓷抗热震性大幅提高的主要原因.     

PI／SiO2纳米杂化薄膜聚集态结构的影响

采用溶胶-凝胶法制备PI/SiO2纳米杂化薄膜.在制备过程中,有机相采用均苯四甲酸二酐(PMDA)和4,4'-二氨基二苯醚(ODA)体系,无机相通过前驱体正硅酸乙酯(TEOS)水解缩舍制得.采用扫描电子显微镜(SEM),原子力显微镜(AFM)等手段表征了PI/SiO2纳米杂化薄膜的微观形貌,并讨论了热亚胺化工艺对PI/SiO2纳米杂化薄膜聚集态结构的影响.研究结果表明,适当提高60℃低温区域停留时间;使亚胺化终止温度达到350℃,并延长350℃的停留时间;减慢高温区升温速率是提高两相相互作用,减少SiO2粒径尺寸的有效方法.     

SiO2/Fe2O3复合颜料的制备工艺

在Fe2O3颗粒的悬浮液中以硅酸钠为硅源,稀盐酸调节反应体系的pH值,合成SiO2-Fe2O3核-壳粒子.研究Fe2O3表面包覆SiO2的影响因素,确定最优改性剂和改性条件.采用XRD、SEM对表面改性前后的Fe2O3进行表征,用酸溶率评价包膜效果.以硅酸钠作为硅源,在反应温度85℃、pH值为9~10、改性时间为2 h时,制备出SiO2-Fe2O3复合颜料.包覆后的Fe2O3的耐温性和耐酸性显著提高,干粉耐温性达到1000℃.     

PI/Al_2O_3/SiO_2杂化薄膜的力学及电学性能

采用原位聚合法制备掺杂无机粒子质量分数从1%~5%的PI/Si O2/Al2O3纳米杂化薄膜.通过SEM发现无机纳米Al2O3和纳米Si O2颗粒在聚酰亚胺基体中有很好的相容性和分散性,其颗粒尺寸大约在100 nm左右.采用万能试验机和宽频介电谱分析仪研究不同浓度Al2O3和Si O2的掺杂对PI薄膜的力学性能和电学性能的影响.当质量分数为3%的时候,杂化薄膜力学性能最佳,具有最大的拉伸强度(36.143MPa)和断裂伸长率(10.88%).并且在100Hz下它相比于其它含量的杂化薄膜,具有最小的介电常数(6.76)、介电损耗(0.01)和电导率(3.94×10-12S·m-1).     

纳米SiO_2/Fe_3O_4磁性流体的制备及其性能表征

以纳米SiO_2类流体中的SiO_2纳米粒子为"核",采用化学镀法将使用共沉淀法合成的Fe_3O_4镀覆到纳米SiO_2类流体上,得到新型的纳米SiO_2/Fe_3O_4磁性流体。采用振动磁强计(VSM)、扫描电子显微镜(SEM)和热失重(TGA)等对新型的纳米SiO_2/Fe_3O_4磁性流体进行了表征,结果表明所制备的磁性流体保持了纳米类流体在常温下液体的可流动性,粒径为230 nm,磁性流体的电导率为2.66×10~(-5)S/cm,饱和磁场强度为2.56 emu/g。在保证纳米类流体特性的情况下,成功赋予了纳米SiO_2类流体磁性功能,并且自身电性能得到了较大的提高。     

Dielectric Behavior of Nano-PbTiO3/PVDF Nanocomposites In-situ Synthesized by the Sol-gel Method

PbTiO3 / PVDF nanocomposites were prepared via in-situ growth of nanosized PbTiO3 particles in PVDF matrix by sol-gel method. Nanosized PbTiO3 grown in the composites film was characterized by X-ray diffractometry （XRD） and transmission electron mieroscopy, and the dielectric properties of the composite films prepared were measured. The distribution of PbTiO3 nanoparticles in-situ grown in the PVDF matrix was examined using a scanning electron microscope. The relative dielectric eonstant increases with increasing the weight fracture of PbTiO3 in-situ grown. In particular, the dielectric loss monotonically decreases with the increase of PbTiO3 content at 1 MHz.     

Fe_3O_4/SiO_2复合粒子的制备及对Cd~(2+)的吸附性能研究

采用共沉淀法制备出粒径为10nm左右、具有超顺磁性的Fe3O4纳米粒子,在Fe3O4纳米粒子外包覆SiO2合成了磁性Fe3O4/SiO2复合粒子,研究了该复合粒子对水溶液中Cd2+离子的吸附性能.利用透射电子显微镜(TEM)、X射线衍射仪(XRD)、红外光谱(FTIR)、振动样品磁强计(VSM)和原子吸收分光光度计(AAS)对样品进行表征,考察了SiO2不同包覆量对吸附剂吸附性能的影响.结果表明:随着SiO2包覆量的增大,SiO2壳层厚度增大,内核中包埋的Fe3O4粒子数量增多,Fe3O4/SiO2复合粒子尺寸随着增大,由50nm左右增大到300 nm左右;Fe3O4纳米粒子表现出了良好的磁性能,比饱和磁化强度达73.6A·m2·kg-1,Fe3O4/SiO2复合粒子的比饱和磁化强度随SiO2包覆量的增大而逐渐减小;Fe3O4/SiO2复合粒子的吸附率随着SiO2包覆量的增多而逐渐增大,最大吸附率为91.0%.     

纳米CaCO3／SiO2复合粒子对硅橡胶性能的影响

硅橡胶力学性能差．需要补强．这是硅橡胶产品开发的关键。本文报道用溶胶沉淀法制备具有核一壳结构的纳米CaCO3／SiO2复合粒子．将该复合粒子替代部分二氧化硅作为硅橡胶的补强材料。通过实验确定它对硅橡胶的力学性能和热稳定性能的影响。比较用纳米CaCO3／SIO2复合粒子以及用CaCO3补强的硅橡胶。前者不仅物理力学性能较佳，而且能降低材料的成本。但后者耐热性能较好。     

纳米CaCO_3/SiO_2复合粒子对硅橡胶性能的影响

硅橡胶力学性能差,需要补强,这是硅橡胶产品开发的关键。本文报道用溶胶沉淀法制备具有核-壳结构的纳米CaCO3/SiO2复合粒子,将该复合粒子替代部分二氧化硅作为硅橡胶的补强材料。通过实验确定它对硅橡胶的力学性能和热稳定性能的影响。比较用纳米CaCO3/SiO2复合粒子以及用CaCO3补强的硅橡胶,前者不仅物理力学性能较佳,而且能降低材料的成本。但后者耐热性能较好。     

PZT/Fe3O4复合薄膜的制备及磁性和铁电性研究

用溶胶-凝胶方法制备了Pb（Zr0.5Ti0.5）O3-Fe3O4复合薄膜。XRD研究表明，Pb（Zr0.5Ti0.5）O3呈完全（100）取向，而Fe3O4颗粒则呈完全随机取向。在室温下探测到了共存的磁性和铁电性。铁电性测试结果表明，在9V的测试电压下，薄膜的Pr值为1．5／μc／cm^2。而磁性测量的结果表明，在1．5 T的外磁场作用下，薄膜的剩余磁化强度和饱和磁化强度分别为0．67emu／cm^3和3．5emu／cm^3。通过铁电材料Pb（Zr0.5Ti0.5）O3与磁性纳米Fe3O4粒子的复合获得了室温共存的铁电性和磁性。     

Preparation and Characterization of Fe2O3/Al2O3 Nano-composites

Al2O3/Fe2O3 nano-composites were prepared by sol-gel route. The effect of Fe2O3content on the structure, grain size and characterization of the composite were investigated through X-ray diffraction and Mssbauer spectrum. The X-ray diffraction results show that Al2O3/Fe2O3 nano-composites with the Fe2O3content of 40 wt% can be obtained after heat-treated at 900 ℃. The Mssbauer effect results show that all samples exhibit clear super-paramagnetic phenomenon. Particles grow and defects reduce with the increasing of Fe2O3content and some α-Fe2O3stay magnetic order.     

Microstructures and Mechanism of Al_2O_3/Al Composites Fabricated by the Reaction between SiO_2 and Molten Aluminum

1　IntroductionAmongtheavailablemethodsforfabricatingcompos ite ,thein situreactionsynthesispossessestechnicalandeconomicadvantages :simpleprocess ,lowfabricationcost .Throughthechemicalreactionbetweenliquidandsolid ,in situreinforcedceramicparticleswithfinedimen sionandgooddistributioncanbeformed .Theparticleshaveawellcombinedinterfacewiththematrixandhavenopollutionofimpurities .Thecompositeobtainedbyin situreactionhasexcellentproperties ,soithaswideap plications .Inthefabricationofthein sit…     

DBSA含量对纳米Fe3O4/导电聚苯胺结构和 电磁性能的影响

以十二烷基苯磺酸（DBSA）为乳化剂和掺杂剂,过硫酸铵（APS）为氧化剂,采用乳液聚合的方法合成了导电聚苯胺包覆磁性四氧化三铁的核-壳纳米复合材料。通过TEM、FTIR、XRD、介电常数和磁导率的测量研究了反应中DBSA的含量对合成纳米颗粒的微观结构和电磁性能的影响。结果表明：当DBSA和苯胺的摩尔比为1.0时,得到的Fe3O4/PANI/DBSA微粒的粒径在120 nm左右,颗粒的分散状态较好;FTIR和XRD的表征说明,DBSA的加入量在很大程度上影响掺杂态聚苯胺的导电性和结晶性;介电常数和磁导率的测     

Y_2O_3-SiO_2 添加剂对 AlN/SiC_W 复合材料性能的影响

利用ＸＲＤ、ＳＥＭ、ＥＰＭＡ和ＨＲＥＭ等测试技术系统地研究了Ｙ２Ｏ３－ＳｉＯ２添加剂对ＡｌＮ／ＳｉＣＷ复合材料力学性能及高温抗氧化性能的影响。结果表明：Ｙ２Ｏ３－ＳｉＯ２添加剂可有效地改善材料的力学性能,材料的氧化过程也是其热处理增强过程。添加剂组成接近其低共熔点时,材料随氧化时间的延长而得到增强增韧,且增幅最大,其最佳掺量为１０ｗｔ％。氧化处理改变了粒界玻璃相的相组成,玻璃相与ＡｌＮ颗粒发生作用,生成ＡｌＮ多形体２ＨδＳｉａｌｏｎ相,形成对材料有益的空间交错的结构。     

Effect of different montmorillonites on rheological properties of bitumen/clay nanocomposites

Different composites of organomodified montmorillonite(OMMT)/bitumen were prepared by melt blending with hexadecyl dimethyl benzyl ammonium modified montmorillonite(HBM) and double octadecyl dimethyl ammonium modified montmorillonite(DOM).The structures of two kinds of montmorillonite modified bitumen were characterized by X-ray diffraction(XRD).The effects of different montmorillonites on the dynamic rheological properties of the modified bitumens were investigated by dynamic shear rheometer(DSR).The XRD results show that DOM modified bitumen forms an intercalated structure,whereas the HBM modified bitumen forms an exfoliated structure.DSR results indicate that OMMT modified bitumens exhibit higher complex modulus,lower phase angle than pristine bitumen,which means that the resistance to rutting at high temperatures of pristine bitumen is improved due to the introduction of OMMT.Compared with DOM modified bitumen,HBM modified bitumen shows better rutting resistance,which is contributed to the formation of exfoliated structure in HBM modified bitumen.     

Effect of different forms of silica on sintering,microstructure and properties of borosilicate glass/Al2O3 composites

The effects of the introduction of silica glass and silica ceramic into Ca-Al-B-Si-O glass/ Al2O3 composites on decreasing the shrinkage and the dielectric constant of samples were investigated by FTIR, DSC, XRD and SEM. The results show that silica ceramic filler can better improve the formation of Si– O–Si network in the composites under high temperature, which leads to increased continuity of glass network at high temperature, and deduces the increase of viscosity of composites and further results in the decrease in the shrinkage of samples. Densification, three-point strength, and dielectric constant of samples decrease with the increase of silica glass or silica ceramic content. By contrast, Ca-Al-B-Si-O glass/Al2O3 composites with 4 wt% silica ceramic exhibit better properties of a bulk density of 2.81 g cm-3, a porosity of 0.3%, a 3dp value of 202 MPa, a ε r value of 7.41, a tan δ value of 8.3×10-4at 10 MHz and a well matching with Ag electrodes. This material is suitable to be used as the LTCC material for the application in wireless communications.     

制备条件对Fe/Al2O3选择性催化还原SO2的影响

不同负载量的Fe/Al2O3催化剂分别以浸渍法、共沉淀法和溶胶-凝胶法制得，对比评价了不同方法制备的催化剂样品以CO为还原剂，选择性催化还原SO2的活性。研究表明，铁催化剂有较高的去除SO2的活性，制备方法对催化剂活性具有显著影响。其中溶胶-凝胶法和共沉淀法最高活性分别可以达到95%和85%左右；而浸渍法样品的活性较差，最高转化率不到60%。3种不同组分催化剂的活性在低温时并不明显，在高温时明显地显示出高的负载量具有高的活性。     

Effects of postthermal treatment and UV irradiation on the structure of titania-polyacrylate nanocomposites

The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO2/polyacrylate nanocomposites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization were investigated, and the hybrid films were characterized by thermal gravimetry analysis （TGA）, X-ray photoelectron spectrum （XPS）, and atomic force microscopy （AFM）. XPS data suggested that the prolongation of irradiation time and the postthermal treatment promoted titania formation, with the former affecting more remarkably. TGA data showed that TiO2-hybrid films could upgrade the decomposition onset temperature （Tonset） as well as the temperature at which there is a maximum mass loss rate （Tmax）. AFM data demonstrated that the inorganic titania particles with a mean diameter of 25.26-28.84 nm were homogeneously distributed in the organic matrix.     

Fe3O4-H2O2类Fenton体系催化降解苯酚

为提出基于新型磁纳米Fe3 O4催化剂的类Fenton体系,采用化学共沉淀法制备磁纳米Fe3 O4,用四甲基氢氧化铵（ TMAH）对所制备的磁纳米Fe3 O4进行表面改性,就Fe3 O4－H2 O2类Fenton体系对苯酚废水的处理效果进行探讨,考察催化剂投量、H2 O2浓度、pH、反应时间等因素对COD和挥发酚去除率的影响．结果表明：磁纳米颗粒平均粒径为30 nm,并在20～100 nm内呈现良好的粒度分布．不同剂量TMAH包覆的3种催化剂经超声预处理后,在室温（13℃）下对50 mg／L苯酚（相当于112 mg／L COD）的降解效果基本一致．当催化剂投量为0．8 mmol／L、H2 O2浓度为2．0 mmol／L、pH为4．5、反应时间180 min时,COD去除率最高可达72％;催化剂投量为0．4 mmol／L、H2 O2浓度为2．0 mmol／L、 pH为4．5、反应时间为90 min时,挥发酚的去除率接近100％．而在重复使用方面,3＃Fe3O4－TMAH（2 mL）催化剂的回用性最好,4次反应COD的去除率分别为73％、29％、28％、26％,挥发酚去除率分别为100％、84％、67％、54％．该类Fenton体系具有不产生多余泥量的优点,且磁纳米催化剂在外磁场作用下可实现快速分离回收．