铁电纳米材料的制备、性能和应用前景

对近年来有关铁电纳米粉体、纳米复合材料、以及纳米陶瓷的制备,结构和性能进行了介绍.对由于粒子尺寸减小引起的结构和性能的改变及其相关机理进行了讨论.透明铁电纳米复合材料可望在光学存储、光学计算等光学器件中得到应用.而纳米陶瓷由于介电特性、耐电压、抗老化、机械强度等性能的提高,因而可以广泛用于改进现有电容器材料的性能,获得性能更加优良的器件.     

纳米陶瓷复合材料的制备与性能

综述了近年来国内外关于纳米陶瓷复材料的研究进展，着重介绍了纳米陶瓷复合材料的制备技术，力学性能的改进情况以及微观结构特点，指出发展纳米陶瓷复合材料是改善陶瓷材料强韧性和高温力学性能的有效途径。     

长寿命的汽车减震器油封在安徽诞生

近日，安徽中鼎密封件股份有限公司和安徽大学攻克以橡胶为基体的陶瓷纳米粉体分散技术“瓶颈”，研制出性能优良的橡胶陶瓷纳米复合材料。     

纳米氮化硼增强金属基复合材料的研究进展

在金属中添加陶瓷增强相是调控和改善金属材料结构和性能的重要途径。传统硬质陶瓷增强相难以满足金属材料日益严苛的应用需求。以氮化硼纳米片（boron nitride nanosheet,BNNS）和氮化硼纳米管（boron nitridenanotube,BNNT）为代表的纳米氮化硼具有极大的比表面积和优异的力学性能、热稳定性、化学稳定性等,是制备性能优异的金属基复合材料的理想增强相。系统总结了纳米氮化硼的种类和特征,综述了纳米氮化硼增强金属基复合材料的制备方法,归纳了纳米氮化硼增强Cu、Al、Ti复合材料的研究成果,总结了纳米氮化硼/金属复合材料的力学和摩擦学性能,并揭示了复合材料性能改善的机理。最后,展望了纳米氮化硼/金属复合材料的发展趋势。     

纳米技术在复合材料中的应用

纳米技术作为材料科学中的一个主要研究重点已经取得众多成就, 通过纳米粒子、纳米管以及各种超微细的结构模块, 导致产生出许多新的具有优异性能和新的应用可能的复合材料。本文介绍了纳米复合材料最新进展, 诸如纳米结构陶瓷, 无机有机复合材料和碳纳米管作填料的应用     

金属和陶瓷界面对复合材料特性的影响

对粉末冶金，挤压铸造和液相铸造工艺制备的各种陶瓷增强铝基，钛基复合材料中金属和陶瓷的界面特性，显微结构，界面对复合材料力性能的影响进行了初步的探讨。研究结果指出，金属和陶瓷界面存在机械结合和反应结合的不同特性，并在受载破坏时表现出不同的断裂形貌，复合材料界面上存在析出相割裂了陶瓷增强相与基体界面的联系，降低了界面结合强度，陶瓷增强相表面的物理、化学状态及基体的化学成分对金属基复合材料的特性具有重要     

UP/Na-MMT纳米复合材料的制备与性能

研究了UP／Na-MMT纳米复合材料的制备与性能，并考察了插层剂种类、有机蒙脱土加入量及离子交换量对复合材料性能的影响。结果表明，UP／Na-MMT纳米复合材料的XRD曲线中蒙脱土晶体结构的布拉格衍射峰已经消失，说明其晶层已被树脂撑开，达到纳米级分散；复合材料的耐热性能得到明显改善，其冲击强度和拉伸强度均有较大提高。     

纳米Cu-Al2O3复合材料的烧结法制备研究

研究了纳米Al2O3陶瓷颗粒增强铜基复合材料制备技术.选用纳米级Al2O3陶瓷颗粒作为增强相,采用超声波增强化学镀的方法完成对纳米Al2O3陶瓷颗粒金属铜包覆,热压烧结成纳米Al2O3陶瓷颗粒增强铜基复合材料,开采用XRD、TEM等分析测试技术对其组织性能进行研究.     

中科院硅酸盐所生物无机纳米复合材料研究取得重要成果

最近，上海硅酸盐所高性能陶瓷和超微结构国家重点实验室高秋明研究员带领的课题组在生物无机纳米复合材料制备及其性能研究中取得重要进展。     

纳米陶瓷复合材料进展EI

综述了近年来纳米陶瓷复合材料的研究进展，着重介绍了纳米陶瓷复合材料的制备技术、力学性能的改进情况以及微观结构特点，并提出了关于发展高强韧耐高温纳米陶瓷复合材料的构想。     

Fracture toughness of zirconia nanoparticle-filled dental composites

The fracture toughness of dental composites containing zirconia nanoparticles dispersed in a bisphenol A glycol dimethacrylate-based monomer blend (GTE) was studied for several yttria contents. Three-point bend test bars with and without a notch were tested at ambient temperature to determine elastic modulus, flexure strength, and fracture toughness. The ZrO₂ nanoparticles increased the fracture toughness of the nanocomposites compared to previous results for the matrix and Schott glass-filled nanocomposites. X-ray diffraction analyses revealed mostly tetragonal ZrO₂ in the nanocomposites before and after testing, in agreement with a theoretical analysis. The enhancement in fracture toughness in ZrO₂-filled nanocomposites was caused mainly by the higher values of particle toughness and interface toughness in GTE/ZrO₂ compared to those of GTE/Schott glass nanocomposites.     

Mechanical Behavior of Nanodiamond/Epoxy Nanocomposites

The mechanical properties of epoxy-based nanocomposites reinforced by nanodiamond (ND) particles were investigated. The results showed that while the addition of 0.1 wt% of ND improved the Young’s modulus and tensile strength compared with those of the pure epoxy, the mode I fracture toughness did not show any improvement. Furthermore, in order to study the effect of shear deformation on fracture properties of nanocomposites, mixed mode fracture resistance of nanocomposites was investigated. It was found that as the share of shear deformation in mixed mode loading increases, the positive effect of ND particles enhances.     

两次挤出制备尼龙66/纳米SiO2复合材料及其结构与性能

通过双螺杆两次挤出技术制得了尼龙66/SiO2纳米微粒复合材料,发现二次挤出的复合材料的拉伸强度、断裂伸长率、杨氏模量、简支梁缺口冲击强度较纯尼龙66均有很大程度的提高,并通过动态力学热分析研究了复合材料的动态力学性能,复合材料的储能模量及玻璃化转变温度均有不同程度的提高。借助SEM分析了复合材料的拉伸断面形貌,并用DSC研究了复合材料的结晶行为。     

Microstructure and mechanical properties of epoxy hybrid nanocomposites modified with acrylic tri-block-copolymer and layered-silicate nanoclay

In this study, processing, morphology and mechanical properties of acrylic tri-block-copolymer and organophilic layered-silicate nanoclay modified epoxy hybrid nanocomposites were investigated. The acrylic tri-block-copolymer preferentially self-assembled into spherical micelles in the epoxy matrix, and predominantly intercalated and few exfoliated platelets were observed with nanoclay. Three-phase ternary nanocomposites showed coexistence of both intercalated nanoclay and nanostructured block-copolymer in epoxy. Experimental results revealed that the block-copolymer significantly enhanced fracture toughness. Increased toughness of epoxy coincided with a reduction of tensile stiffness and strength. The nanoclay filled nanocomposites exhibited superior stiffness and slight improvement in tensile strength while compromising ductility. Optimum property enhancement was observed in the case of epoxy hybrid nanocomposites. Mechanical properties of the hybrid nanocomposites depend on microstructure, dispersion state and the ratio between organic and inorganic nanofiller contents.     

Mechanical property and R-curve behavior of the B4C/BN ceramics composites

The B₄C/BN ceramics composites were fabricated by the hot-pressing process. In this paper, the mechanical property and R-curves behavior of the B₄C/BN composites were investigated. The fracture strength and fracture toughness of the B₄C/BN microcomposites and the B₄C/BN nanocomposites decreased gradually with the increasing content of h-BN. The fracture strength and fracture toughness of the B₄C/BN nanocomposites were significantly improved in comparison with the B₄C/BN microcomposites. The damage resistance and R-curves behavior of the B₄C monolith and the B₄C/BN composites were evaluated by the indentation-strength in bending technique (ISB). The fracture strength of the B₄C monolith, the B₄C/BN microcomposites and the B₄C/BN nanocomposites decreased gradually with the increase of the indentation load. The B₄C/BN nanocomposites retained relative higher fracture strength in comparison with the B₄C monolith and the B₄C/BN microcomposites under the equivalent indentation load. The B₄C monolith, the B₄C/BN microcomposites and the B₄C/BN nanocomposites all exhibited the rising R-curves behavior. The B₄C/BN nanocomposites exhibited the higher rising R-curve behavior than that of the B₄C monolith and the B₄C/BN microcomposites. The toughness mechanisms of the composites were investigated. The B₄C/BN composites with the h-BN content more than 20 wt.% exhibited excellent machinability. The slowly rising R-curves behavior remarkably improved the machinability of the composites.     

马来酸酐接枝聚丙烯对聚丙烯/蒙脱土纳米复合材料的影响

研究了相容剂马来酸酐接枝聚丙烯对聚丙烯/蒙脱土纳米复合材料(PP/MM T)的影响,它不仅显著改善了PP与蒙脱土的界面相容性,使复合材料力学性能显著提高,而且改善了复合材料的加工流动性。PP的断裂方式属典型的脆性断裂,含有马来酸酐接枝聚丙烯的PP/MM T断裂方式属韧性断裂。蒙脱土在聚丙烯结晶时起成核剂的作用,提高了PP/MM T纳米复合材料的结晶速率。相容剂使得有机蒙脱土对PP的成核作用更加明显。     

低填充SiO2/聚丙烯纳米复合材料的拉伸特性

通过对纳米SiO2辐照接枝聚合改性,结合熔融共混工艺制备了低填充SiO2/PP纳米复合材料,发现在一定拉伸速度和粒子含量下,经辐照改性的SiO2/PP纳米复合韧性得到显著提高,同时强度也有所增加,随拉伸速度的升高,纳米复合材料的模量和强度逐渐增大,而韧性则随之下降,断面扫描电镜观察表明,改性纳米粒子填充复合材料韧性提高的机理以空化和基体大面积剪切屈服为主。     

低填充SiO_2/聚丙烯纳米复合材料的拉伸特性

通过对纳米 Si O2 辐照接枝聚合改性 ,结合熔融共混工艺制备了低填充 Si O2 / PP纳米复合材料。发现在一定拉伸速度和粒子含量下 ,经辐照改性的 Si O2 / PP纳米复合材料韧性得到显著提高 ,同时强度也有所增加。随拉伸速度的升高 ,纳米复合材料的模量和强度逐渐增大 ,而韧性则随之下降。断面扫描电镜观察表明 ,改性纳米粒子填充复合材料韧性提高的机理以空化和基体大面积剪切屈服为主     

Mechanical behaviour and essential work of fracture of halloysite nanotubes filled polyamide 6 nanocomposites

Polyamide 6 (PA 6)/halloysite nanotubes (HNT) nanocomposites were prepared by melt-extrusion compounding via masterbatch dilution process. A homogeneous dispersion of HNTs in PA 6 matrix was achieved. Differential scanning calorimetric measurements showed that addition of HNTs into PA 6 matrix enhanced the crystallization temperature and degree of crystallinity, thus indicating an effective nucleation induced by the addition of HNTs. Upon halloysite addition, glass transition temperature, storage modulus, Young modulus, tensile strength and notched Charpy impact strength increased without loss of ductility. For the first time, the essential work of fracture (EWF) concept was used to analyse the toughening and fracture behaviour of PA 6/HNT systems. Significant increase (+38%) of the essential work of fracture of PA 6/HNT nanocomposites was noticed at HNTs contents as low as 4 wt.%.     

Micro- and nano-scale deformation behavior of nylon 66-based binary and ternary nanocomposites

The primary aim of this paper is to provide an insight on the effect of the location of organoclay on the micro- and nano-scale deformation processes in melt-compounded nylon 66/organoclay/SEBS-g-MA ternary nanocomposites prepared by different blending sequences. In addition, the deformation processes of the ternary nanocomposites were compared to the binary nanocomposites (nylon 66/organoclay and nylon 66/SEBS-g-MA) and neat nylon 66. The incorporation of SEBS-g-MA particles toughened nylon 66 markedly; but the flexural modulus and strength were both reduced. Conversely, the use of organoclay increased the modulus but decreased the fracture toughness of nylon 66. Nylon 66/SEBS-g-MA/organoclay ternary nanocomposites exhibited balanced elastic stiffness and toughness. Stress-whitening studies of the fracture surfaces in terms of gray level were also performed and an attempt was made to correlate the optical reflectivity characteristics with fracture toughness. It was concluded that the capability of SEBS-g-MA particles to cavitate was decreased by the presence of organoclay in the SEBS-g-MA phase, resulting in reduced toughening efficiency. The best micro-structure for toughness and other mechanical properties is thus to maximize the amount of exfoliated organoclay in the nylon 66 matrix rather than to have it embedded in the finely dispersed SEBS-g-MA particles.