聚合物-锂改性蒙脱石复合材料离子迁移

以聚合物（ＰＥＯ,ＰＥＯ－ＰＭＭＡ）和锂改性蒙脱石作为主要原料,采用聚合物粉末直接熔融嵌入的方法,制备聚合物－蒙脱石复合材料．利用ＮＭＲ、ＡＣ阻抗等分析方法探讨了复合材料中聚合物链对 Ｌｉ＋离子迁移的影响．结果表明,聚合物（ＰＥＯ）嵌入蒙脱石层间,层间聚合物链的无序度增大,有利于Ｌｉ＋离子迁移．ＰＭＭＡ引入对ＰＥＯ链的改性,进一步加大聚合物链的无序度,更易于层间Ｌｉ＋离子迁移;复合材料的常温离子电导率接近１０－２Ｓ·ｃｍ－１,且具有良好的温度稳定性．     

SiO2粉末在非水高浓度聚合物溶液中的分散

ＳｉＯ_２粉末在非水高浓度聚合物溶液中的分散陈立富（厦门大学化学系,厦门,３６１００５）关键词ＳｉＯ_２,氢键,分散剂无机粉末（如碳,ＳｉＯ２等）与高分子聚合物组成的复合材料可优化高聚物的导电性能、机械性能及化学稳定性等。一般来说,只有当非常细小的粉末...     

聚环氧乙烷/LixMoO3纳米复合材料的制备及表征

介绍了聚环氧乙烷（ＰＥＯ）／ＬｉｍＭｏＯ３纳米复合材料的制备过程。结果表明,ＰＥＯ大分子插入到ＬｉｘＭｏＯ３片层间,使层间距增大了０．７３ｎｍ。ＰＥＯ在ＬｉｘＭｏＯ３层间呈ＰＥＯ－ＨｇＣｌⅠ型构象,其运动能力受到限制。     

一类新型PTC复合材料的制备及性能

一类新型ＰＴＣ复合材料的制备及性能杜伟坊,杜海清（湖南大学材料科学及应用化学研究所,长沙,４１００８２）关键词正温度系数,聚乙烯,ＹＢａ_２Ｃｕ_３Ｏ_（７－ｘ）具有正温度系数（ＰＴＣ）的材料在其转化温度附近具有电阻率大幅度上升的特点,因而在温度检测与?..     

填充增韧聚丙烯复合材料的断裂韧性及增韧机理

用表面处理的ＣａＣＯ３填充聚丙烯（均聚物ＰＰ），ＰＰ／ＣａＣＯ３复合材料的杨氏模量和缺口冲击强度同时得到增加，克服了通常填料填充聚合物降低韧性的缺点．用Ｊ积分研究其断裂韧性给出：裂纹扩展阻力ｄＪ／ｄ（△ａ）低是聚丙烯缺口脆性的主要原因，随着填料体积分数Ｖｆ的增加ＰＰ／ＣａＣＯ３的Ｊｃ出现一极大值，但其裂纹扩展阻力却不断增大；用裂纹引发点后的Ｊｃ＝Ｊｃ＋［ｄＪ／ｄ（△ａ）］·△ａ＝Ｊｅ（Ｊ积分弹性分量）＋Ｊｐ（Ｊ积分塑性分量）可全面表征韧性聚合物材料的断裂韧性；ＰＰ／ＣａＣＯ３的Ｊｐ明显增加，是裂纹扩展阻力和Ｊｔ增加的原因．ＳＥＭ分析结出，ＣａＣＯ３填料在裂尖损伤区内引起强烈的空洞化损伤，并增强了裂尖钝化破坏过程，这些细观损伤机制的变化，导致能量耗散增加，可用滞后分量Ｊｈ定量表征．由此给出聚合物材料被增韧的Ｊ积分判据为：复合材料的Ｊｈ＞基体的Ｊｈｍ．     

电沉积ZrO2—Ni功能梯度材料的组织结构分析

电沉积ＺｒＯ２┐Ｎｉ功能梯度材料的组织结构分析①全成军＊向兴华朱景川尹钟大（哈尔滨工业大学材料科学与工程学院哈尔滨１５０００１）航空航天技术的高速发展对材料的耐热性能提出了更苛刻的要求，传统的单一材料（如陶瓷、金属）和金属陶瓷复合材料已难以在超高温和...     

自生氧化铝颗粒增强铝基复合材料的扫描电镜和原子力显微镜的对比研究

用扫描电镜（ＳＥＭ）、原子力显微镜（ＡＦＭ）等分析技术研究了一种Ａｌ／Ａｌ２Ｏ３自生颗粒复合材料的微观形貌，结果表明，７００～７５０℃气－液反应生成的氧化铝自生颗粒的典型尺寸为亚微米级，颗粒与基体之间具有热力学稳定性。     

聚酰亚胺/二氧化硅纳米尺度复合材料的研究

通过正硅酸乙酯（ＴＥＯＳ）在聚酰胺酸（ＰＡＡ）的Ｎ，Ｎ’ 二甲基乙酰胺（ＤＭＡｃ），溶液中进行溶胶 凝胶反应，制备出不同二氧化硅含量的聚酰亚胺／二氧化硅（ＰＩ／ＳｉＯ２）复合薄膜材料．二氧化硅含量低于１０ｗｔ％的样品是透明浅黄色薄膜；二氧化硅含量高于１０ｗｔ％的样品是不透明棕黄色薄膜．利用红外光谱、扫描电镜、热失重分析、动态力学分析、热膨胀系数测试和应力 应变测试等方法研究了此类材料的结构与性能．结果表明，ＰＩ／ＳｉＯ２纳米复合材料具有较聚酰亚胺更高的热稳定性和更高的模量；线膨胀系数显著降低；拉伸强度和断裂伸长随二氧化硅含量而变化，分别在１０ｗｔ％和３０ｗｔ％附近出现最大值     

八乙墓卟啉和四苯基卟啉合钌（Ⅱ）及锇（Ⅱ）的二氧加合物的红外光谱

ＯＥＰ（八乙基卟啉阴离子）和ＴＰＰ（四苯基卟啉阴离子）合钌（Ⅱ）和锇（Ⅱ）的二氧加合物由ｍａｔｒｉｘ分离技术得到（Ｔ＝２０－４３Ｋ，Ｐ＝１０－５－１０－６ｔｏｒｒ）．为了确定ｖ（Ｏ２）带的归属应用了同位素取代法１６Ｏ２／１８Ｏ２．ＩＲ谱说明对于钌的两种加合物（指ＯＥＰ和ＴＰＰ）都有两种异构体，其Ｖ（１６Ｏ２）频率为：Ｒｕ（ＯＥＰ）Ｏ２，１１４１和１１０３ｃｍ－１；Ｒｕ（ＴＰＰ）Ｏ２，１１６７和１１１４ｃｍ－１．Ｏｓ（ＴＰＰ）Ｏ２只生成一种异构体，ｖ（１６Ｏ２）＝１０９０ｃｍ－１，异构体ｖ（１６Ｏ２）：［Ｒｕ（ＯＥＰ）Ｏ２］，１１４１ｃｍ－１，［Ｒｕ（ＴＰＰ）Ｏ２］，１１６７ｃｍ－１，这些加合物约在１００Ｋ时分解，它们的结构指定为ｅｎｄｏｎ，而异构体［Ｒｕ（ＯＥＰ）Ｏ２］，１１０３ｃｍ－１，［Ｒｕ（ＴＰＰ）Ｏ２］，１１１４ｃｍ－１和［Ｏｓ（ＴＰＰ）Ｏ２］，１０９０ｃｍ－１，在２４０—２７０Ｋ分解，它们的结构指定为桥联二聚体．在加合物中，将ＯＥＰ换成ＴＰＰ引起的钌加合物ｖ（Ｏ２）频率的改变比铁和钴加合物更大．ｖ（Ｏ２）相对强度的变化顺序为：Ｆｅ（Ⅱ）→Ｒｕ（Ⅱ）→Ｏｓ（Ⅱ）．     

碳酸钙填充高密度聚乙烯复合材料冲击断口形貌的研究

用扫描电镜观察了碳酸钙（ＣａＣＯ３）／高密度聚乙烯（ＨＤＰＥ）复合材料的冲击断口形貌．发现以１２５０目轻质ＣａＣＯ３填充的ＨＤＰＥ,其断口形貌一般呈带状结构;以１２５０目重质ＣａＣＯ３或３２５目轻质ＣａＣＯ３填充的ＨＤＰＥ,其断口形貌一般呈絮状结构．带状的成因是包覆的ＣａＣＯ３粒子具有几乎各向同性地向四周传递应力的能力,满意地解释了带状的平行方向可以与宏观受力方向平行、垂直或成某种夹角,但总是与微观的某一基体屈服、变形的方向垂直．带状与絮状结构是断口形貌的两种形式,不表征冲击强度的高低     

二氧化硅修饰纳米氧化锆陶瓷材料的制备及性能

以二甲基二乙氧基硅烷为硅源,在水溶液中成功制备了SiO2修饰纳米ZrO2颗粒;利用透射电子显微镜、热重分析仪、X射线衍射仪、红外光谱仪分析了样品的形貌和结构;将SiO2/ZrO2与α-Al2O3制成陶瓷材料,考察了其机械性能.结果表明,所制备的SiO2/ZrO2晶粒均一,直径约为10nm,硅原子在SiO2/ZrO2中以Si―O―Zr键合形式存在,SiO2不影响ZrO2的晶型.引入SiO2使得ZrO2晶粒细化、尺寸均匀性提高;SiO2/ZrO2/Al2O3陶瓷气孔率小,具有致密的显微结构和优异的机械性能.     

Plasma electrolytic synthesis and characterization of pH-sensitive TiO2-ZrO2-ZrTiO4-CeOx films on titanium

Journal of Solid State Electrochemistry - The Ti/TiO2 + ZrO2, Ti/TiO2 + CeOx, and Ti/TiO2 + CeOx + ZrO2 composites, including Y-doped ones, have been...     

Ablation properties of C/C–SiC composites tested on an arc heater

Carbon fiber-reinforced carbon and silicon carbide (C/C–SiC) composites were fabricated by a combination of chemical vapor infiltration and liquid silicon infiltration. Ablation properties of C/C–SiC composites and C/C composites with similar technique were tested on a high-pressure arc heater. The results show that ablation properties of C/C–SiC composites are more severe than those of C/C composites. Ablation of C/C–SiC composites includes oxidation, sublimation of SiC (Si), and mechanical denudation. Oxidation and sublimation of SiC (Si) lead to the enlarged ablation rates between carbon fibers and matrices, which finally cause serious ablation of C/C–SiC composites.     

颗粒弥散Ba0.5 Sr0.5 Co0.8 Fe0.2 O3-δ基复合透氧膜材料的制备、结构与性能研究

Dense oxygen permeable membranes are expected to have great impact on oxygen production and oxygen involved industrial processes. Ba0.5Sr0.5Co0.8Fe0.2O3-δ is of highest oxygen permeability at elevated temperatures. A novel composite ceramic preparation route for Ba0.5Sr0.5Co0.8Fe0.2O3-δ was developed by directly produced stable BaZrO3 based secondary phase particles(SPP) via addition of ZrO2 and iso molar excess BaO, aiming at improving mechanical properties. It revealed that as synthesized composites could get a well developed and fine grained microstructure, there being secondary phase particles as the grain growth inhibitor, and the mechanical properties and oxygen permeation are improved. For the composite with addition of 10% ZrO2+10% BaO, a well developed and fine grained microstructure has been obtained. Compared to the pure phase BSCF5582, the three point bending strength of the composite with addition of 5% ZrO2+5% BaO increases by 68% and its oxygen permeation rate is much higher below 850℃ with the smaller apparent activation energy. Additionally, the electrical properties of the composites are also affected by the inclusion of SPP: conductivity decreases with the SPP content increasing, while the hysteresis of conductivity declines due to the relative stable carrier concentration.     

Evaluation of mechanical properties and characterization of silicon carbide–reinforced polyamide 6 polymer composites and their engineering applications

In this article, the tensile strength, impact, and hardness properties of silicon carbide (SiC) reinforced with polyamide 6 (PA6) are described for the first time. The composites were fabricated by an injection molding method using the SiC with varying weight percentages. The tensile and hardness of SiC/PA6 composites showed a regular trend of increasing tensile strength, impact, and hardness properties with varying weight percentages until 10 wt% and impact strength of SiC/PA6 composites increased up to 5 wt% afterwards decreasing the mechanical properties of the composite with greater weight percentages. Scanning electron microscope (SEM) studies were carried out to evaluate the SiC/PA6 interactions. The results related to SiC/PA6 composites were compared with those obtained for pure PA6.     

添加稀土氧化物助剂的CeO2-ZrO2固溶体的储氧性及热稳定性研究

大多数工业催化剂都是在稳定的操作条件下进行的,然而汽车尾气净化催化剂却被暴露在大气中,使用条件经常变化,尤其是空燃比(A/F)的变化,直接影响了对氧敏感的三效催化剂的氧化和还原性能[1].CeO2则是一种具有储氧/释氧能力的催化材料,它作为助剂加入三效催化剂中,可在贫况下储存氧(以Ce4+存在)利于NOx的还原,在富况下释放氧(以Ce3+存在),利于HC、CO的氧化,从而提高了催化剂的活性.然而,CeO2 的储氧性通常局限在表面上,当温度超过400℃以上时,其比表面积降低从而引起储氧性能急剧下降,直接影响催化剂的性能和寿命.     

Ti-ZrO_2系金属陶瓷的氧化性能研究

本文研究了由等体积比的Ti与 5Y TZP热压合成的金属陶瓷的抗氧化性能 .首先进行了热力学分析 ,证实在 0 .1MPa的空气氛中发生高温反应时 ,只发生氧化反应而不会氮化 .研究表明其氧化动力学规律与纯钛类似 ,只是材料中ZrO2 的存在使氧的扩散阻力增大 ,表现为扩散活化能远高于氧在钛氧固溶体中的扩散活化能 ;氧化初期恒温增重曲线符合抛物线规律 .XRD和TEM分析证明 ,氧化产物的主晶相为金红石结构的TiO2 ,此外还有少量的ZrTiO4 .氧化层表面和断面的SEM分析表明 ,氧化膜中存在两种类型的裂纹 ,ZrO2 /Ti(或TiO2 )的界面裂纹主要是由加热或冷却过程中因ZrO2 与Ti(或TiO2 )的热膨胀系数失配而造成的 .氧化层中出现平行于氧化表面的裂纹产生于氧化层与基体的界面应力 ,ZrO2 的存在能于一定程度上抑制此类裂纹的扩展     

Mechanical and thermal properties of epoxy/silicon carbide nanofiber composites

The silicon carbide (SiC) nanofibers (0.1, 0.25, and 0.5 phr), produced by self‐propagating high‐temperature synthesis (SHS), are used to reinforce the epoxy matrix cured with an anhydride hardener. Morphological studies reveal a better dispersion of SiC nanofibers and a good level of adhesion between nanofiber and the matrix in composites with lower (0.1 and 0.25 phr) nanofiber loading. The flexural studies show that a maximum increase in flexural properties is obtained for composites with 0.25 phr SiC nanofiber. The fracture toughness of epoxy is found to increase with the incorporation of SiC nanofibers, and 0.25 phr SiC nanofiber loading shows maximum fracture toughness value. The possible fracture mechanisms that exist in epoxy/SiC nanofiber composites have been investigated in detail. Thermogravimetric analysis reveals that SiC nanofibers are effective fillers to improve the thermal stability of epoxy matrix. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of ZrO2-carbon nanotube composites and their application as chemiluminescent sensor material for ethanol

ZrO2-carbon nanotube (CNT) composites have been successfully synthesized via decomposition of Zr(NO3)4.5H2O in supercritical carbon dioxide-ethanol solution with dispersed CNTs at relatively low temperatures. The samples were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) analyses. It was demonstrated that CNTs were fully coated with an amorphous ZrO2 layer, and the coating layer was nominally complete and uniform. In addition, the thickness of the coating sheath could be readily controlled by tuning the Zr(NO3)4.5H2O/CNTs ratio used. Furthermore, the chemiluminescent sensor prepared from ZrO2-carbon nanotube composites exhibited dramatic sensitivity as well as high stability and selectivity to ethanol.     

Microstructure and properties of silicon carbide whisker reinforced zirconium diboride ultra-high temperature ceramics

Hot-pressed zirconium diboride (ZrB₂) matrix composites containing 0–30 vol% silicon carbide (SiC) whiskers have been investigated to determine the effect of composition (i.e. amount of SiC whiskers) on the microstructure, mechanical properties and thermal properties. With increasing SiC whisker volume contents, the flexural strength and fracture toughness of the composites were improved compared to those of monolithic ZrB₂. Flexural strength increased from 629 MPa for pure ZrB₂ to 767 MPa for ZrB₂–30 vol%SiCw. Likewise, fracture toughness ranged from 5.4 to 7.1 MPa m^1/2 over the same composition range. Specific heat capacity increased with SiC whisker addition, while thermal diffusivity and thermal conductivity decreased slightly with the increase of SiC whisker content.