纳米SiO2增韧增强氰酸酯制备工艺的研究

从纳米SiO2三种不同的分散工艺(研磨法、偶联剂表面处理法和高速均质剪切法)着手,通过原位聚合法制得SiO2/氰酸酯(CE)纳米复合材料;采用透射电镜分析(TEM)、扫描电镜分析(SEM)和热失重分析(TGA)研究了三种分散工艺对纳米SiO2的分散以及复合材料的力学性能和热性能的影响.结果表明,研磨对纳米SiO2的分散优于高速均质剪切,偶联剂表面处理分散较差;高速均质剪切对复合材料力学性能和热性能的提高程度优于研磨法,当纳米SiO2含量为1phr时,高速均质剪切所得复合材料的冲击强度和弯曲强度分别比纯CE提高35.0%和12.1%;当质量损失为5%时复合材料的热分解温度较纯CE提高23.8℃;偶联剂表面处理法则降低了复合材料的弯曲强度和热分解温度.     

SiO2 / 氰酸酯纳米复合材料的力学性能和热性能

采用高速均质剪切法制备了SiO₂ / 氰酸酯(CE) 纳米复合材料, 并对该体系的静态力学性能、动态力学性能和热稳定性进行了研究。结果表明, 纳米SiO₂的加入提高了复合材料的冲击强度和弯曲强度。当SiO₂ 含量为0. 30 wt %时, 复合材料的冲击强度达最大, 增幅为88. 9 %; 当SiO₂含量为0. 15 wt %时, 材料的弯曲强度达最大, 增幅为2010 %。复合材料的储能模量和高温损耗模量较纯CE 树脂有明显提高, 玻璃化转变温度比纯CE 提高了31. 2 ℃, 热分解温度在SiO₂含量为0. 30 wt %时达最大, 失重为10 %时的热分解温度提高了25. 7 ℃。      

氰酸酯树脂/γ-巯丙基三甲氧基硅烷改性碳化硅复合材料的制备及性能研究

采用γ-巯丙基三甲氧基硅烷偶联剂(KH-590)对碳化硅粉体(SiC)进行了表面改性,制备了氰酸酯树脂/碳化硅(CE/SiC)复合材料。研究了SiC含量对复合材料的静态力学性能、电绝缘性能、导热性能和摩擦性能的影响,以扫描电子显微镜对复合材料的断面形貌进行了观察。结果表明,少量SiC粉体的引入能有效改善复合材料的静态力学性能、耐磨性能,且复合材料仍保持良好的电绝缘性能。当SiC的质量分数在6%～8%时,复合材料的冲击强度、弯曲强度相对于纯CE分别提高了89. 6%和67. 6%;当SiC的质量分数在8%时,复合材料的导热系数增大4. 6倍,摩擦系数比纯CE降低了43. 5%,耐磨性相对于纯CE提高77. 5%。     

纳米Si_3N_4/双马来酰亚胺/氰酸酯树脂复合材料的性能

双马来酰亚胺树脂预聚体改性的氰酸酯树脂(BMI/CE)具有良好的机械性能和热性能,是一种多功能复合材料树脂基体。本文研究了纳米Si3N4的含量对BMI/CE复合材料力学性能和摩擦学性能的影响,并通过扫描电镜和透射电镜分析了复合材料的增韧机理、磨损机理以及纳米Si3N4在基体中的分散性。结果表明:纳米Si3N4可显著改善复合材料的力学性能和摩擦学性能。当纳米Si3N4含量为3.0wt%时,复合材料的力学性能和摩擦学性能最好。相对于BMI/CE树脂基体,复合材料的冲击强度提高了36.0%,弯曲强度提高了21.8%,摩擦系数降低了25.0%,磨损率降低了77.9%。纳米Si3N4粒子可较好地分散在树脂基体中,起到均匀分散应力的作用,从而增强材料的韧性;BMI/CE树脂为塑性变形和粘着磨损,而纳米Si3N4含量为3.0wt%时复合材料为粘着磨损。     

KH－560改性CE／nano—SiC复合材料的韧性和耐热性

采用模塑成型法制备CE／nano-SiC复合材料,通过冲击强度测试、TGA分析和DMA分析,发现偶联剂KH-560表面处理nano—SiC后,对其韧性和耐热性具有显著的协同改性作用。相对纯CE,经KH-560表面处理后的CE、1．00％nano—SiC复合材料,冲击强度提高86．26％;玻璃化转变温度提高16．71％;失重5％时,热分解温度提高17．25％;450℃时,质量保持率提高59．67％。     

纳米SiO_2改性氰酸酯/聚丙烯腈聚合物性能研究

应用聚合物网络技术,通过制备氰酸酯(CE)/聚丙烯腈(PAN)网络聚合物,再以纳米Si O2改性,制得聚合物复合材料。采用红外光谱、透射电子显微镜等手段表征了该复合材料的微观结构,测定了其力学性能。结果表明,该三组分复合材料CE/PAN/3%Si O2,在CE/PAN为85/15时,其力学性能均达到最佳状态,冲击强度和弯曲强度比纯CE分别提高了83.11%和12.84%;添加3%纳米Si O2的聚合物与未添加Si O2的相比,其冲击强度再次提高了30.31%,弯曲强度提高了17.16%;红外光谱和透射电镜测试分析结果表明,组成网络的各复合材料组分之间未发生化学反应。互穿提高了复合材料承担载荷的能力,从而提高了CE的强度与韧性。     

偶联剂表面处理纳米SiO2填充CE/BMI体系的力学性能

本文研究了纳米二氧化硅(nano-SiO2)的含量对nano-SiO2/氰酸酯(CE)/双马来酰亚胺的预聚体(BMI)复合材料力学性能的影响;测量了用不同的硅烷偶联剂处理的nano-SiO2对水和甘油的相对接触角,利用Fowkes-Good几何方程计算了nano-SiO2的表面自由能,考察了经不同硅烷偶联剂处理的nano-SiO2对nano-SiO2/CE/BMI复合材料力学性能的影响.并通过扫描电镜分析nano-SiO2在基体中的分散性及增韧机理.结果表明,nano-SiO2对CE/BMI有增韧增强效果,当nano-SiO2含量为2.0wt%时复合材料的冲击、弯曲强度均最好;硅烷偶联剂处理可以增强纳米nano-SiO2的疏水性并降低其表面能,改善了其在基体中的分散性,有利于提高nano-SiO2/CE/BMI复合材料的冲击强度.     

热压烧结制备SiC增强石墨复合材料及其性能

以天然鳞片石墨为起始原料,SiC颗粒为增强相,采用热压烧结工艺制备了SiC增强石墨复合材料。研究了SiC含量对SiC增强石墨复合材料微观结构、力学性能和摩擦性能的影响。结果表明:SiC颗粒均匀分布在石墨基体中,降低了基体中的孔隙率;随着SiC含量增加,SiC增强石墨复合材料的相对密度和弯曲强度相应增加,开孔率显著降低,当SiC含量达到40vol%时,SiC增强石墨复合材料中形成了SiC网络骨架结构,相对密度达到了94.2%,比商品高强纯石墨材料提高了11.8%,弯曲强度达到了146 MPa,比商品高强纯石墨材料提高了147%;基体石墨保持了层状结构;SiC含量低于40vol%时,SiC增强石墨复合材料的摩擦系数随SiC含量的增加轻微增加,与纯石墨材料的摩擦系数相当,具有良好的摩擦性能。     

氰酸酯树脂/氧化石墨烯纳米复合材料的制备及表征

通过溶液插层的方法制备氰酸酯树脂/氧化石墨烯纳米复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和热重分析(TGA)研究纳米复合材料的结构和性能,采用电子万能试验机研究纳米复合材料的力学性能。研究表明,异氰酸苯酯改性氧化石墨在二甲基甲酰胺中经超声处理后剥离形成氧化石墨烯薄片;添加氧化石墨烯后纳米复合材料的力学性能和耐热性显著改善。当氧化石墨烯的含量为基体树脂的1%时,纳米复合材料的拉伸强度、弯曲强度和冲击强度分别为82.9 MPa、148.6 MPa和12.9 kJ/m2,1000℃时的残炭率达45.1%。     

氧化石墨烯/双马来酰亚胺树脂纳米复合材料的制备及性能

通过溶剂超声剥离法制备氧化石墨烯/双马来酰亚胺(BMI)树脂纳米复合材料。采用X射线衍射(XRD)、透射电镜(TEM)和热重分析(TGA)对纳米复合材料进行表征,并对其力学性能进行研究。结果表明,在N,N-二甲基甲酰胺中超声能有效地将异氰酸苯酯改性的氧化石墨剥离成氧化石墨烯薄片;这种纳米复合材料比BMI树脂具有更好的力学性能和耐热性能,当氧化石墨烯含量为基体树脂的1%时,其拉伸强度、弯曲强度和冲击强度分别为87.7 MPa、142.1MPa、15.9 kJ/m2,当氧化石墨烯含量为1.25%时,其1000℃时的残炭率达41.3%。     

纳米SiC/PA66复合材料的研究

采用SiC填充PA66制备出纳米SiC/PA66复合材料。讨论了纳米SiC对PA66耐磨损性能的影响 ,结果表明 :当纳米SiC含量分别在 1 0 %、3%时 ,纳米SiC/PA66复合材料的冲击性能和耐腐蚀性能以及拉伸性能最好 ;并通过扫描电镜对PA66和纳米SiC/PA66的结构进行表征     

To improve interfacial and mechanical properties of carbon fiber–modified nano-SiC–epoxy composites using dispersion and wetting control

Significant improvements in mechanical properties (particularly stiffness) result from the appropriate addition of micro-carbon fibers in the nano and heterostructures of modified nano-SiC-filled epoxy matrix composites. The optimum dispersion conditions were found to be significantly dependent upon both the amount of nano-SiC filler and the sonication time. To investigate these dispersion effects, composites were fabricated with five different nano-SiC filler concentrations and compared to the untreated composite. Changes in electrical capacitance were used as a measure of the comparative degree of dispersion in these nano-SiC–epoxy composites. FE-SEM was used to observe the interfacial changes for the different surface conditions, and the mechanical damage was evaluated by inspection of fractured surfaces. Optimal conditions of dispersion, interfacial adhesion, and aspect ratio of the modified nano-SiC fillers were found to improve the composites’ mechanical properties.     

Nano-SiC reinforced Zn biocomposites prepared via laser melting:Microstructure,mechanical properties and biodegradability

Zn has been regarded as new kind of potential implant biomaterials due to the desirable biodegradability and good biocompatibility,but the low strength and ductility limit its application in bone repairs.In the present study,nano-SiC was incorporated into Zn matrix via laser melting,aiming to improve the mechanical performance.The microstructure analysis showed that nano-SiC distributed along Zn grain boundaries.During the laser rapid solidification,nano-SiC particles acted as the sites for heterogeneous nucleation,which resulted in the reduction of Zn grain size from 250 μm to 15 μm with 2 wt%SiC(Zn-2 SiC).Meanwhile,nano-SiC acted as a reinforcer by virtue of Orowan strengthening and dispersion strengthening.As a consequence,the nanocomposites showed maximal compressive yield strength(121.8±5.3 MPa) and high microhardness(72.24±3.01 HV),which were increased by 441% and 78%,respectively,compared with pure Zn.Moreover,fracture analysis indicated a more ductile fracture of the nanocomposites after the incorporation of nano-SiC In addition,the nanocomposites presented favorable biocompatibility and accelerated degradation caused by intergranular corrosion.These findings suggested that the nano-SiC reinforced Zn biocomposites may be the potential candidates for orthopedic implants.     

丝网印刷nano-SiC薄膜阴极的电子特性的研究

研究了低成本大面积丝网印刷在玻璃衬底上均匀的纳米碳化硅(nano-SiC)薄膜的场致发射特性。提出了机械分散团聚的nano-SiC的方法,实验了适合导电玻璃衬底上制备nano-SiC薄膜的浆料配方,摸索导电玻璃衬底上nano-SiC薄膜的烧结工艺,研究了不同nano-SiC含量的薄膜的场发射特性,得到了最佳场致发射特性的配方比例。对样品进行微观分析和表征。具有稳定均匀场致发射性能的nano-SiC薄膜可作为显示器器件的阴极材料。     

纳米SiC与石墨填充PTFE复合材料的摩擦磨损性能

考察了不同含量的纳米SiC对石墨/聚四氟乙烯复合材料摩擦磨损性能的影响,采用扫描电子显微镜分析了磨损表面,并探讨了其磨损机理。结果表明:纳米SiC与石墨能够很好地协同增强聚四氟乙烯,纳米SiC的加入大大提高了复合材料的承载能力,石墨的加入减少了纳米SiC与对偶面的摩擦系数,从而降低了纳米SiC的脱落趋势,提高了复合材料的耐磨性。当纳米SiC含量为5%时,5%石墨/PTFE复合材料表现出最佳的耐磨性,具有一定的应用价值。     

An investigation on electroless Cu–P composite coatings with micro and nano-SiC particles

Cu–P/micro-SiC and Cu–P/nano-SiC composite coatings were deposited by electroless plating and their composition and microstructure were observed by EDX (energy-dispersive analysis), SEM (scanning electron microscope) and XRD (X-ray diffraction). The corrosion resistance, microhardness and the wear resistance of the Cu–P/nano-SiC composite coatings were measured and the comparison with those of Cu coatings and Cu–P/micro-SiC coatings were given. The anti-corrosion properties of Cu coatings were investigated in 3.5% NaCl solution by the potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. Among three kinds of Cu–P based coatings, the corrosion resistance, hardness and wear resistance of Cu–P/nano-SiC coatings were the largest. This indicates that the precipitation of nano-SiC particles would improve the corrosion resistance, hardness and wear resistance of the Cu–P coatings significantly.     

Effect of a new additive on mechanical properties of hot-pressed silicon carbide ceramics

The mechanical properties and microstructure of SiC ceramics, hot pressed by simultaneously adding nano-SiC and oxides (MgO+Al₂O₃+Y₂O₃) or nitrate salts (Mg(NO₃)₂+Al(NO₃)₃+Y(NO₃)₃) as additives, were evaluated. The oxide additives system slightly influenced the mechanical properties of the ceramics, while the addition of nano-SiC lead to finer microstructure, and 5 vol.% nano-SiC changed the fracture mode from intergranular type to transgranular type. The ceramics with nitrate salts had fine, equiaxed grains with an average grain size larger than that of the system added oxides, thus inducing lower Viker’s hardness and flexural strength, while the presence of crystalline YAG phase improved the fracture toughness by 54.7%. Also, an observed increase in grain growth—with decreasing weight fraction of liquid and the grounded grain morphology in this system—confirmed a diffusion-controlled growth mechanism. Although the sample with the least amount of additives has the lowest relative density and largest grain size, its flexural strength did not drastically decrease. The influence of nano-SiC on the fracture toughness in the nitrate additive system was negligible.     

Dual-nanoparticulate-reinforced aluminum matrix composite materials

Aluminum (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nano-SiC) were fabricated by mechanical ball milling, followed by hot-pressing. Nano-SiC was used as an active mixing agent for dispersing the CNTs in the Al powder. The hardness of the produced composites was dramatically increased, up to eight times higher than bulk pure Al, by increasing the amount of nano-SiC particles. A small quantity of aluminum carbide (Al(4)C(3)) was observed by TEM analysis and quantified using x-ray diffraction. The composite with the highest hardness values contained some nanosized Al(4)C(3). Along with the CNT and the nano-SiC, Al(4)C(3) also seemed to play a role in the enhanced hardness of the composites. The high energy milling process seems to lead to a homogeneous dispersion of the high aspect ratio CNTs, and of the nearly spherical nano-SiC particles in the Al matrix. This powder metallurgical approach could also be applied to other nanoreinforced composites, such as ceramics or complex matrix materials.     

激光选区熔化纳米SiC/AlSi7Mg复合材料微观组织及力学性能EI北大核心CSCD

采用机械混合法制备纳米SiC/AlSi7Mg混合粉末,利用激光选区熔化技术(selective laser melting,SLM)成形纳米SiC颗粒增强AlSi7Mg复合材料,观察和分析试样的相对密度、物相和微观组织,并测试材料的硬度和拉伸性能。结果表明:SLM成形纳米SiC/AlSi7Mg复合材料试样的相对密度随着扫描速度和扫描间距的增大均呈现先增加后减少的趋势,相对密度最高可达99.75%;试样微观组织与SLM成形铝合金相似,Si相呈网状结构均匀嵌入α-Al基体中,且在Al基体中存在与Si分布相似的纳米SiC团聚物及Mg_(2)Si相;与AlSi7Mg相比,复合材料微观组织由柱状晶转化为等轴晶,且晶粒明显细化(平均晶粒尺寸为1.36μm);由于SiC的加入,产生细晶强化和固溶强化,试样的硬度和强度均明显提高,硬度最高达到137.3HV,抗拉强度达到448.3 MPa,屈服强度达到334.7 MPa,但伸长率下降至3.9%,断裂模式主要为脆性断裂。