酞菁铜-Fe3O4纳米复合粒子复合机理及其性能的研究

制备了酞菁铜（ＣｕＰｃ）－Ｆｅ３Ｏ４纳米复合粒子,分析了ＣｕＰｃ与Ｆｅ３Ｏ４纳米粒子的复合过程,提出了其复合机理。研究并建立了ＣｕＰｃ－Ｆｅ３Ｏ４纳米复合粒子的结构模型,研究了复合粒子的抗氧化性和热性。结果表明,ＣｕＰｃ与Ｆｅ３Ｏ４纳米粒子之间形成了化学键。在复合过程中,首先一部分ＣｕＰｃ与Ｆｅ３Ｏ４纳米粒子表面的氧离子形成化学键;然后Ｆｅ３Ｏ４纳米粒子发生聚集,形成聚集体;最后相当一部分ＣｕＰＣ     

新型EMR液的ER和MR性能研究

制备了金属酞菁 (MPc) - Fe3O4纳米复合粒子 (M=Co,Cu,Ni,Mn)与氯化石腊油组成了 EMR液 ,研究了其ER、MR性能。结果表明 ,此类 EMR液在较低的电场和磁场作用下就表现出较强的 ER、MR活性。在外加电场作用下 ,EMR液的剪切应力变化值 Δτ与外加电场强度基本上呈线性关系 :Δτ=α·E。在外加磁场作用下 ,EMR液的 Δτ～γ关系符合 Bingham关系式 :Δτ=Δτy H ηHγ。 ηH 随着 H的增加而增大。     

B2O3和CaF2对C3S-C2.75B1.25A3S-C2S-C3A水泥熟料矿物体系力学性能影响

研究了B2O3和CaF2对C3S-C2.75B1.25A3S-C2S-C3A熟料矿物体系的组成、结构与力学性能的影响.研究结果表明:在该熟料体系中C3S,C2.75B1.25A3S,C2S和C3A的适宜含量分别为50%,10%,25%和15%,B2O3和CaF2的适宜掺量为2%和1.5%.在最佳组成和制备工艺条件下,合成的阿利特-硫铝酸钡钙水泥的1d,3d和28d抗压强度分别达到18MPa,48MPa和95MPa以上,展现了良好的早期力学性能.同时,掺加CaF2能有效降低熟料中游离氧化钙的含量,促进阿利特在低温条件下形成.利用SEM-EDS,XRD等测试手段对熟料的组成、结构及性能进行了分析.     

Effects of porosity distribution variation on the liquid water flux through gas diffusion layers of PEM fuel cells

Flooding of the membrane electrode assembly (MEA) and dehydrating of the polymer electrolyte membrane have been the key problems to be solved for polymer electrolyte membrane fuel cells (PEMFCs). So far, almost no papers published have focused on studies of the liquid water flux through differently structured gas diffusion layers (GDLs). For gas diffusion layers including structures of uniform porosity, changes in porosity (GDL with microporous layer (MPL)) and gradient change porosity, using a one-dimensional model, the liquid saturation distribution is analyzed based on the assumption of a fixed liquid water flux through the GDL. And then the liquid water flux through the GDL is calculated based on the assumption of a fixed liquid saturation difference between the interfaces of the catalyst layer/GDL and the GDL/gas channel. Our results show that under steady-state conditions, the liquid water flux through the GDL increases as contact angle and porosity increase and as the GDL thickness decreases. When a MPL is placed between the catalyst layer and the GDL, the liquid saturation is redistributed across the MPL and GDL. This improves the liquid water draining performance. The liquid water flux through the GDL increases as the MPL porosity increases and the MPL thickness decreases. When the total thickness of the GDL and MPL is kept constant and when the MPL is thinned to 3 μm, the liquid water flux increases considerably, i.e. flooding of MEA is difficult. A GDL with a gradient of porosity is more favorable for liquid water discharge from catalyst layer into the gas channel; for the GDLs with the same equivalent porosity, the larger the gradient is, the more easily the liquid water is discharged. Of the computed cases, a GDL with a linear porosity 0.4x + 0.4 is the best.     

THERMO-ELASTIC-PLASTIC RESPONSE AND OPTIMUM DESIGN OF CERAMIC-METAL FGMS-CYCLIC THERML LOADING PROBLEM

The materials are made with a graded composition and microstructure in the thickness direction from the ceramic side to the metal side. The cyclic thermal loading and high temperasure gradient environment are simulated by heating the ceramic surface with a cyclic heat flux input and cooling the metal surface with a flawing liquid niterogen. The thermal and thermo-elastic-plastic response of the materials is calculated using the isotropic hardening model and kinetic hardening model. Emphasis is     

TiC/Fe体系自蔓延高温合成过程中金属相Fe的作用

本文探讨了金属相Ｆｅ的含量变化对ＴｉＣ／Ｆｅ体系自蔓延高温合成的影响。随着Ｆｅ含量的增高，燃烧温度降低，在Ｆｅ为３０～３５ｗｔ％时出现一个温度平台，对应着Ｆｅ的熔融。燃烧波速度在Ｆｅ为１０ｗｔ％时出现极大值，反映ＳＨＳ过程中Ｆｅ液相的作用。Ｆｅ含量增高，体系的燃烧模式由稳态燃烧转变为振荡式和螺旋式燃烧，当Ｆｅ＞６０ｗｔ％时，体系燃烧反应则不能自持。合成产物中ＴｉＣ粒度随着Ｆｅ含量增高而变细，反映了燃烧温度和铁液相对ＴｉＣ粒子生长的联合作用。     

TiC纳米晶粉的制备及特性

采用机械合金化方法制备了ＴｉＣ纳米晶粉末，研究了这种纳米晶粉末的微观结构和性能。结果表明，机械合金化处理５０ｈ，可以获得平均粒径为３０ｎｍ的ＴｉＣ纳米晶粉，其显微硬度随着球磨时间的增加而大幅度提高。     

正电子湮没技术用于新型硫铝酸盐基无宏观缺陷水泥的研究

探索了正电子湮没技术(positron annihilation technique,PAT)测定硫铝酸盐基无宏观缺(macro-defect-free,MDF)水泥中微细孔的实验方法。结果表明:正电子湮没中等寿命成分(τ2≈330 Ps)的强度I2随水泥中微细孔(<250 A)等的增加而有规律地增大,因此可用I2的大小来表征硫铝酸盐基MDF水泥的密实程度和结构完整性。同时,还将实验结果与水银压入法(mercury instrusion porosimeter,MIP)测试结果进行了对比。     

石墨—MDF水泥基复合材料屏蔽电磁波性能

研究了石墨、聚合物（ＰＶＡ）及材料厚度对石墨－ＭＤＦ（Ｍａｃｒｏ－Ｄｅｆｅｃｔ－Ｆｒｅｅ）水泥基复合材料屏蔽电磁性能的影响及其机理。结果表明：当石墨添加量超过１８ｖ．％时，材料对２００１６００ＭＨｚ的电磁波有１０－４０ｄＢ的衰减效果，屏蔽效率Ｓ随材料中聚合物增加而降低，随材料厚度增加而升高，随电磁波的频率ｆ的增加有升高的趋势。当石墨在水泥基体里形成导电网络时，材料的电阻率ｐｖ发生显著变化，即出现渗     

四电极质子补偿法测量质子交换膜的电导率

对已有的质子交换膜电导率的测试方法进行了分析，针对影响准确测量电导率的因素而设计了一种四电极质子补偿测试法．结果表明，该方法与传统的四电极测试法相比，简单方便、精度较高，能有效地避开极化与测量时间的影响，具有广泛的实用性．