Zr1-xHfxW2O8 (x=0,0.3,0.5,0.7,0.8,1.0)的合成及负热膨胀特性的研究

采用固相化学反应的方法 ,成功合成了立方结构的Zr1 -xHfxW2 O8(x =0 ,0 .3,0 .5 ,0 .7,0 .8,1 .0 )系列材料 .高、低温X射线衍射分析表明 ,Hf4+替代Zr4+对Zr1 -xHfxW2 O8的负热膨胀系数影响不大 .在 373K～ 973K温度范围 ,Zr1 -xHfxW2 O8线膨胀系数αl 约为 - 6× 1 0 - 6K- 1 ;在83K～ 2 98K温度范围Zr0 .5Hf0 .5W2 O8的αl =- 9.6× 1 0 - 6K- 1 .     

Al/Y_2W_3O_(12)复合材料的制备、热膨胀及电性能研究

采用固相法制备Al/Y_2W_3O_(12)复合材料,研究了Al与Y_2W_3O_(12)以不同质量比合成样品的特性。X射线衍射表明:样品只含有Al和Y_2W_3O_(12),不存在Al对Y的取代。SEM和EDS分析表明:小颗粒Y_2W_3O_(12)嵌入在块状Al基底中,为嵌入式复合结构。热膨胀性能和电导率测试分析表明:当Al与Y_2W_3O_(12)的质量比7∶3时,Al/Y_2W_3O_(12)样品的线膨胀系数14.76×10-6/K(RT~600℃)约为Al的一半,呈现良好的导电性,其导电率为18.2 S/m可达Al的电导率的1/2,且Al/Y_2W_3O_(12)样品几乎不表现出吸水性。研究认为,该复合材料具有低膨胀和较高导电性是由于其特有的嵌入式结构所致。     

负热膨胀固溶体ZrW_(1.8)V_(0.2)O_(7.9)有序度参数影响因素研究

用酸蒸汽水热-相转变法合成了异价取代W位置的立方ZrW1.8V0.2O7.9固溶体.测定了立方ZrW1.8V0.2O7.9和ZrW2O8在不同温度的晶胞参数和有序度,讨论了ZrW1.8V0.2O7.9和ZrW2O8有序度与保温时间和外界压力之间的关系.结果表明,立方ZrW1.8V0.2O7.9表现出负热膨胀的性质.ZrW1.8V0.2O7.9和ZrW2O8的有序度随保温时间的增长而逐渐变大,真空条件下的有序度高于常压下的有序度.     

尼龙11/热膨胀石墨纳米复合材料的制备与表征

采用直接熔融共混的方法制备了尼龙11/热膨胀石墨纳米复合材料,用X射线衍射(XRD)、热重分析(TGA)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉伸和电导率测试等手段研究了尼龙11/热膨胀石墨(PA11/TEG)纳米复合材料的微观结构和性能.结果表明,石墨的高温热处理能有效剥离石墨片层,单独的石墨片层厚度...     

Y0.18-xYbxTa0.18Zr0.64O2材料的相结构、相稳定性和热膨胀性能研究

采用固相反应法制备了Yb2O3-Y2O3-Ta2O5-ZrO2陶瓷材料(简称YbTYSZ).分别利用X-ray衍射(XRD)仪、扫描电子显微镜(SEM)和高温综合热膨胀仪对陶瓷材料的物相组成及相稳定性、显微结构和热膨胀性进行了分析.XRD结果表明:1 873 K烧结6 h的YbTYSZ陶瓷材料由单一的四方相组成,且经1 573 K等温热处理250 h后仍表现为单一的四方相结构,说明该陶瓷材料在高温下具有良好的相稳定性.随着Yb3+掺杂量增多,晶粒尺寸增大且变的均匀.此外,在室温至1 573 K,YbTYSZ陶瓷材料的平均热膨胀系数呈现先减小后增大的规律.     

Al2-xYxW3O12的合成与热膨胀特性的研究

用共沉淀法合成了Al2-xYxW3O12(x=0～2)系列氧化物材料．实验结果表明,通过调整稀土钇(Y)的含量,可以使氧化物的本征热膨胀系数和宏观热膨胀系数逐渐由正到负变化．但是由于其结构的各向异性,多晶陶瓷内部存在的微裂纹使热膨胀曲线出现较大的滞后环．     

Mg70(A0.25Ni0.75)30合金结构及储氢性能

为研究稀土元素Ce、Y对非晶储氢合金催化及其性能的影响,采用快淬法制备Mg70(A0.25Ni0.75)30(A=Ce,Y)合金,使用Sievert’s气体吸附技术和差示热扫描技术研究其储氢性能和热力学稳定性。XRD衍射分析显示,快淬制备的合金为非晶合金,但在573K、2MPa的氢压下,氢化后的Mg70(Y0.25Ni0.75)30会产生MgH2、Mg2NiH4和2相,Mg70(Ce0.25Ni0.75)30会产生Mg2NiH4、CeNi5和MgH2相。不同温度的动力学测试结果表明,快淬法制备的Mg70-(Ce0.25Ni0.75)30和Mg70(Y0.25Ni0.75)30合金分别获得的最大吸氢量为质量分数4.42%和3.09%,Mg70(Ce0.25Ni0.75)30和Mg70(Y0.25Ni0.75)30合金前100s吸氢量分别达到各自最大吸氢量的97%和87%。通过对DSC曲线的分析发现,Mg70(A0.25Ni0.75)30的脱氢活化能较低,分别为111.025±2.790kJ/mol(A=Ce)、84.843±2.057kJ/mol(A=Y)和152.207±6.764kJ/mol(A=Y)。实验结果表明,Y元素对Mg70(A0.25Ni0.75)30合金催化及储氢性能的改善要优于Ce元素。     

Mn2O3/PANI的制备及其防腐性能研究

采用溶剂热法制备Mn_2O_3微球,与化学氧化法制备的聚苯胺按不同比例混合,制得Mn_2O_3/PANI,将其涂覆于Q235碳钢表面制备复合涂层.采用扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射(XRD)和红外光谱(FTIR)表征Mn_2O_3/PANI的表面形貌和结构,利用动电位极化和电化学阻抗谱研究复合涂层的耐蚀性能.结果表明,当Mn_2O_3在复合材料中的质量分数为10%时,防腐性能最优.在3.5%NaCl溶液中浸泡7天后,相较于Q235裸钢,其自腐蚀电位正移约380 mV,自腐蚀电流密度降低约3个数量级;浸泡37天后,其仍有良好的稳定性和耐蚀性.     

N201负载Fe(Ⅲ)复合材料对Sb(Ⅲ)的深度吸附和再生试验研究

通过静态和动态吸附试验研究强碱性凝胶型阴离子交换树脂N201负载Fe(Ⅲ)复合材料对水中Sb(Ⅲ)的吸附性能及其再生方法。结果表明:N201-Fe(Ⅲ)对Sb(Ⅲ)的最大静态吸附容量为610μg/g,最佳pH值为7,在有SO_4~(2-)、Cl~-等竞争离子共存条件下,N201-Fe(Ⅲ)仍然对Sb(Ⅲ)具有高效的选择性吸附能力;动态吸附容量为94.05 mg/L;EDTA为最佳再生剂,在动态条件下再生度达到85%。     

La(Fe0.94Co0.06)11.8Si1.2循环磁化过程中微观结构的演变

电弧熔炼制备的铸态La(Fe0.94Co0.06)11.8Si1.2合金在1 373 K(120 h)热处理之后冰水快淬得到了NaZn13相金属间化合物.将材料应用于自制磁热循环装置中,在其居里点Tc附近进行磁化-去磁化循环处理.经过绝热循环磁化5千次后,通过扫描隧道显微镜观察到化合物La(Fe0.94Co0.06)11.8Si1.2的磁畴细化;通过HRTEM观察到化合物晶粒内部出现了应变区,在[001]方向聚集了大量的位错线.循环磁化8千次后,晶粒内部出现了亚晶界、微观裂缝结构等不可逆结构演变.磁畴结构与微观结构的演变是相互联系、相互影响的,经过不断的循环磁化去磁化处理,材料将会出现磁热性能和结构的同时衰变.     

热电能源材料研究进展

在介绍热电材料的背景、发展历史、主要应用的基础上,概括了目前提高热电材料性能的方法。主要包括:通过态密度共振和能带简并来提高Seebeck系数;通过掺杂点缺陷、纳米结构和多晶晶界等方法对声子进行全方位散射来降低晶格热导率;通过基体和纳米第二相的能带对齐来维持电传输性能;使用本征低热导率材料等。最后对热电材料的研究进行了总结和展望。     

Structure,Electrical Conducting and Thermal Expansion Properties of Ln0.6Sr0.4Co0.8Fe0.2O3 （Ln = La,Pr, Nd,Sm） Ceramics

Ln0.6Sr0.4Co0.2Fe0.2O3 （Ln=La, Pr, Nd, Sm） perovskite-type complex oxides were synthesized using a glycine-nitrate process, and the structure, electrical conducting and thermal expansion properties of the resulting ceramics were examined with regard to the nature of the lanthanide cations. The results indicated that the La, Pr and Nd specimens had a rhombohedral symmetry, while an orthorhombic structure was determined for the Sm specimen. The pseudo-cubic lattice constant decreased with smaller lanthanide cations. It was found that the electrical conducting properties declined with decreasing lanthanide cation size. Fortunately, all the compositions remained rather high electrical conductivities exceeding 650 Ω ^-1m·cm^-1 in the intermediate temperature range （600-800 ℃）. An appreciable thermal expansion increase at high temperatures was detected for all the compositions. Decreasing the size of the lanthanide cations resulted in an increase of thermal expansion. With respect to the high electrical conductivities, the Ln0.6Sr0.4Co0.8Fe0.2O3 oxides are considered to be acceptable as mixed conducting component in composite cathode designs together with doped ceria electrolytes.     

Structure Electrical Conducting and Thermal Expansion Properties of Ln0.6Sr0.4Co0.8Fe0.2O3 (Ln=La,Pr,Nd,Sm)Ceramics

Ln0.6Sr0.4Co0.8Fe0.2O3 (Ln=La, Pr, Nd, Sm) perovskite-type complex oxides were synthesized using a glycine-nitrate process, and the structure, electrical conducting and thermal expansion properties of the resulting ceramics were examined with regard to the nature of the lanthanide cations. The results indicated that the La, Pr and Nd specimens had a rhombohedral symmetry, while an orthorhombic structure was determined for the Sm specimen. The pseudo-cubic lattice constant decreased with smaller lanthanide cations. It was found that the electrical conducting properties declined with decreasing lanthanide cation size. Fortunately, all the compositions remained rather high electrical conductivities exceeding 650Ω1.cm-1 in the intermediate temperature range (600-800℃). An appreciable thermal expansion increase at high temperatures was detected for all the compositions. Decreasing the size of the lanthanide cations resulted in an increase of thermal expansion. With respect to the high electrical conductivities, the Ln0.6Sr0.4Co0.8Fe0.2O3 oxides are considered to be acceptable as mixed conducting component in composite cathode designs together with doped ceria electrolytes.     

云南香茅油热力学数据的研究

利用一维非稳态导热原理，通过实验和数据处理，得到了云南香茅油及其单离香料香茅醇、香卟醇、香茅醛、乙酸香叶酯和乙酸香茅酯的导温系数、导热系数和热容．它们可作为精密精馏塔工艺设计的原始数据．所用方法对于其它香料和有机溶液物性的测定也是实用的．     

Mechanical,electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

The mechanical, electrical, and thermal expansion properties of carbon nanotube（CNT）-based silver and silver–palladium（10：1, w/w） alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young＇s modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion（CTE）. The hardness and Young＇s modulus of the nanocomposites were increased by 30%？40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.     

Sm填充方钴矿化合物的合成及热电性能

采用高温熔融法结合固相反应法合成了一系列单相的SmyFexCo4-x-Sb12化合物，并探索了Sm填充分数对其热电性能的影响规律。结果表明，随着Sm填充分数的增加，载流子浓度及电导率降低；塞贝克系数随温度的升高和Sm填充分数的增加而增大；晶格热导率随Sm填充分数的增加先减小然后再增加，在某一填充分数时达到最小值。Sm0．19Fe1.47Co2．53Sb12化合物显示最大热电性能指数，在750K时其最大无量纲热电性能指数ZTmax值达0．55。     

固体氧化物燃料电池连接体研究进展

首先介绍了作为固体氧化物燃料电池(SOFC)连接体材料所必备的条件和特性,然后对目前已被开发的SOFC连接体材料在高温环境下存在的问题作了概括性的评述,并指明了各种连接体材料的今后发展趋势.最后着重指出含稀土元素及其它微量元素的铁素体不锈钢是今后平板型SOFC连接体材料研究的一个重要方向.     

Experimental study on thermophysical properties of C/C composites at high temperature

Ablationthermalprotectivecompositesarethekeystructureofspacevehiclesprotectingthemfromaerody namicheatingduringtheirreentryintotheaerosphere.Thecarbonmatrixcompositesarethemostpromisingablationmaterialsusedinthisenvironmentduetotheirpotentiallyfavorablepr…