活性泡沫炭用于超级电容器电极材料

以酚醛树脂、煤沥青泡沫炭为原料,经水蒸气活化制得比表面积分别为961和953m2/g的活性泡沫炭。采用扫描电镜、BET吸附仪、恒流充放电法和循环伏安法对两种活性泡沫炭的结构进行了表征并研究其充放电性能。结果表明,酚醛树脂泡沫炭在1.0nm以下的孔较煤沥青泡沫炭丰富。在1.0mA充放电时,两者的充放电容量分别为106.28和105.1F/g,相差不大,当充放电电流增大到50mA时,前者容量为41.94F/g,后者为17.23F/g。可见,微孔的孔径分布对充放电性能具有很大影响,增大微孔的孔径有利于提高活性炭电极的充放电容量和功率。循环伏安法测试表明在100mV/min扫描速率下酚醛树脂泡沫炭粉的电化学窗口大于煤沥青泡沫炭粉。     

碳纳米管增强铝基复合泡沫的阻尼性能

通过填加造孔剂方法制备了碳纳米管（CNTs）增强铝基复合泡沫,采用热机械分析仪研究了测试温度、频率、外加振幅、泡沫的孔隙率和CNTs含量对其阻尼性能的影响,并分析了相关阻尼机制。结果表明:复合泡沫铝的阻尼性能随孔隙率和振幅的增大而提高,随着频率的增加而下降。在环境测试温度25~200℃范围内,复合泡沫的损耗因子变化较小;当温度高于200℃后,损耗因子随温度升高有明显的提高。CNTs的加入可以显著提高泡沫铝的阻尼性能,常温下3.0% CNTs增强的铝基复合泡沫的损耗因子达0.27,为泡沫铝的3.71倍。复合泡沫的阻尼机制主要为位错阻尼、晶界阻尼、孔隙阻尼、CNTs的本征阻尼和CNTs-Al间界面阻尼,其中本征和界面阻尼发挥了重要的增强作用。      

闭孔碳微球泡沫材料制备工艺与性能研究

依据微胶囊化原理,用热固性线型酚醛树脂制得微胶囊,加热去除囊芯后用作先驱体,在N2保护下进行900~1100℃的碳化处理得到具有无定型碳结构的闭孔碳微球,然后在Ar气保护下进行2100~2600℃的石墨化处理,得到具有石墨结构的闭孔微球碳泡沫材料。该材料的导热系数在5W/m.K左右,是一种理想的耐高温隔热泡沫材料。     

Synthesis of silica microspheres on silicon-modified carbon foams under ablation

Silica microspheres (SMs) were in situ synthesized in silicon-modified porous carbon foams (SCFs) by an economic and efficient technique – high temperature oxyacetylene torch ablation. The microstructure and formation mechanism of SMs were analyzed in detail. Results showed that the resultant SMs generally were several microns in diameter, and mainly distributed in the ablation center zone. The formation mechanism was governed by the vapor–liquid–solid principle during the process of ablation and cooling. The influence of the ablative flame on the physicochemical property of SCFs was the leading cause of the bizarre SMs.     

Hierarchically porous carbon foams for electric double layer capacitors

The growing demand for portable electronic devices means that lightweight power sources are increasingly sought after. Electric double layer capacitors (EDLCs) are promising candidates for use in lightweight power sources due to their high power densities and outstanding charge/discharge cycling stabilities. Three-dimensional (3D) self-supporting carbon-based materials have been extensively studied for use in lightweight EDLCs. Yet, a major challenge for 3D carbon electrodes is the limited ion diffusion rate in their internal spaces. To address this limitation, hierarchically porous 3D structures that provide additional channels for internal ion diffusion have been proposed. Herein, we report a new chemical method for the synthesis of an ultralight (9.92 mg/cm³) 3D porous carbon foam (PCF) involving carbonization of a glutaraldehydecross-linked chitosan aerogel in the presence of potassium carbonate. Electron microscopy images reveal that the carbon foam is an interconnected network of carbon sheets containing uniformly dispersed macropores. In addition, Brunauer–Emmett–Teller measurements confirm the hierarchically porous structure. Electrochemical data show that the PCF electrode can achieve an outstanding gravimetric capacitance of 246.5 F/g at a current density of 0.5 A/g, and a remarkable capacity retention of 67.5% was observed when the current density was increased from 0.5 to 100 A/g. A quasi-solid-state symmetric supercapacitor was fabricated via assembly of two pieces of the new PCF and was found to deliver an ultra-high power density of 25 kW/kg at an energy density of 2.8 Wh/kg. This study demonstrates the synthesis of an ultralight and hierarchically porous carbon foam with high capacitive performance.

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煤基炭泡沫孔结构调控

以肥煤镜质组富集物为前驱体, 采用高压渗氮法制备煤基炭泡沫, 研究了发泡温度、发泡压力和发泡时间对炭泡沫孔结构的影响。利用SEM观察炭泡沫的孔胞形貌, 同时利用Nano Measurer分析软件统计SEM照片孔胞直径分布和孔喉直径分布以及平均孔径。结果表明: 微孔塑料成核理论可以定性解释炭泡沫的孔结构变化趋势。发泡温度的升高导致成核密度增加, 同时导致气体在胶质体的溶解度降低, 不利于孔胞长大。发泡压力的增大导致炭泡沫的孔胞密度增加, 临界成核半径降低, 同时加剧了热聚合反应, 导致胶质体的粘度增大, 不利于孔胞长大。发泡时间的延长会使热聚合更加充分, 影响胶质体粘度, 进而影响孔结构。     

中间相沥青基炭泡沫体的制备、结构及性能

以合成中间相萘沥青为原料，采用加压发泡法制备孔径均匀的初生炭泡沫体，经700℃～1000℃和2300℃～2800℃热处理制备出炭化和石墨化炭泡沫体；以700℃炭化处理所得的炭泡沫体作为芯材制成夹芯复合材料。研究了原料性能、发泡以及热处理工艺参数对炭泡沫微观结构和力学性能的影响，考察了炭泡沫体夹芯复合材料的微波吸收性能。结果表明：发泡过程中保持均匀的温度场是制备孔径均匀的炭泡沫体的关键因素，压力是影响孔结构的主要因素。炭泡沫体的微晶结构、力学性能以及微波吸收性能沿xy和XZ面方向（分别表示垂直和平行于重力方向）具有各向异性。     

酚醛树脂为前驱体制备多孔碳泡沫材料

以液态酚醛树脂为前驱体,正戊烷为发泡剂,吐温80为匀泡剂,在高压釜中通过卸压发泡的方法制备了酚醛树脂泡沫,然后将其经1000℃碳化后得到碳泡沫.研究结果表明,所得的典型碳泡沫样品是一种以无定形碳结构为主的轻质多孔碳材料,密度约为0.15g/cm3.碳泡沫的微结构可以通过调节卸压速率而得到有效控制,当卸压速率为0.05MPa/min时,可以得到孔洞相互贯穿、平均孔径约为300μm且分布较为均匀、接点完好,韧带光滑的多孔碳泡沫.     

前驱体对炭泡沫孔结构的影响

分别以煤沥青、石油中间相沥青和AR沥青为前驱体制备炭泡沫材料。采用GPC测定前驱体分子量,SEM观察所制炭泡沫的孔结构,光学显微镜测量所制炭泡沫的孔径及其分布。结果发现,由于煤焦油沥青不含中间相,且QI含量较高,导致在实验条件下不能直接制备出合格的炭泡沫。以石油中间相沥青和AR沥青为原料均能制备出具有分布均匀开孔结构,且微观各向异性的炭泡沫。由AR沥青制备的炭泡沫呈现平均孔径较小(212μm)、孔壁较薄、孔径分布较窄(180μm~300μm)、开孔率较高、以及韧带排列较规整等特点,表明低QI含量、低分子量且分布较窄的前驱体有利于发泡。     

加热条件对炭泡沫材料孔结构和性能的影响

以AR沥青为原料,利用高压釜在不同恒温条件下制备了炭泡沫,并测定了其孔结构、体积密度、显气孔率、压缩强度、常温热导率以及微晶参数.结果表明:相对于短恒温时间,长恒温时间制得的炭泡沫孔径大(412nm)、显气孔率高(83.82%)、体积密度小(0.34g/cm~3)、压缩强度高(4.92MPa),多孔连通结构更丰富.经过石墨化处理后,石墨泡沫呈现出较高的常温热导率(71.34W/(m·K))和较小的层片间距d_(002)(0.33556nm).石墨泡沫的常温比导热率能达到210(W·(m·K)~(-1)) /(g·cm~(-3)),是铜的5倍,铝的4倍.     

以芳基乙炔为前驱体制备高强度炭泡沫(英文)

以硫酸为催化剂,芳基乙炔为前驱体,经聚合、正戊烷发泡、炭化获得了高强度炭泡沫。通过选择合适的制备条件,如:发泡剂的用量,催化剂的浓度及用量,以及匀泡剂吐温80的添加量,可以制得孔结构良好、韧带和接点光滑的炭泡沫。芳基乙炔聚合物泡沫炭化后高的残炭率(86%)和良好的孔结构赋予炭泡沫较高的机械强度;所制炭泡沫的耐压强度达到25.8MPa,强度/密度比为43.0MPa/(g.cm-3).     

单层网壳结构风振响应的主要贡献模态识别

网壳结构具有频谱分布密集、振型复杂的动力特性，在对该类结构进行风振响应分析时，通常存在着一些对响应贡献较大的高阶振型，但由于其频率较高而容易被忽略。因此，研究网壳结构风振响应的主要贡献模态分布规律有利于提高结构风振响应计算的精度和效率。本文利用Ritz-POD法，分析了单层球面网壳和单层柱面网壳结构风振响应的主要贡献模态，着重考察了主要贡献模态的自身参振能力。及其与脉动风压空间分布模式之间的关系。在此基础上，初步给出了网壳结构风振响应的主要贡献模态识别准则。     

Preparation and characterization of ultra-low density porous gold foams

We present a simple approach to generate ultra-low density porous gold foams with the density as low as 0.519 gcm^-3. In our work, gold nanoparticles with small grain sizes and good solubility were prepared and used as starting building blocks; afterwards, the freeze-dry technique was employed to prepare gold compound foams. Finally the gold compound foams were sintered to obtain porous gold foams with ultra-low density. The results show that the content of gold element in the foams is close to 99.2%. Even though the density is as low as 0.519 gcm^-3 the foams still have good intensity and can be machined to simple regular shapes. The microstructure analysis results indicate that the gold foams have continuous open structure, the average pores size is about 1-2 μm, and the framework of the gold foams is piled up with gold particles of different sizes. Our approach might give a way to produce low-density gold foams with simple fabrication procedures.     

由中间相沥青制备泡沫炭:Fe(NO3)3的影响

以中间相沥青为前驱体制备高性能泡沫炭，在考察中间相沥青、Fe（NO3）3及其混合物热分解行为的基础上，着重研究了Fe（NO3）3对制备中间相沥青基泡沫炭的影响，揭示了Fe（NO3）3对泡沫炭孔泡结构的影响规律及其作用机制，初步研究了在泡沫炭炭化过程中形成的Fe／C之物相结构及其石墨化行为。结果表明，在不同的炭化温度下，Fe在泡沫炭中的存在形态各异；Fe物种的存在有利于提高泡沫炭的石墨化程度。     

Compressive properties of closed-cell aluminum foams with different contents of ceramic microspheres

In this paper, closed-cell aluminum foams with different kinds and contents of ceramic microspheres are obtained using melt-foaming method. The distribution and the effects of the ceramic microspheres on the mechanical properties of aluminum foams are investigated. The results show that both kinds of ceramic microspheres distribute in the foams uniformly with part in the cell wall matrix, some in adhere to the cell wall surface and part embed in the cell wall with portion surface exposed to the pores. Ceramic microspheres have an important effect on the yield strength, mean plateau stress, densification strain and energy absorption capacities of aluminum foams. Meanwhile, the content of ceramic microsphere in aluminum foams should be controlled in order to obtain good combination of compressive strength and energy absorption capacity. The reasons are discussed.     

导电硅橡胶泡沫材料的制备与性能研究

在硅橡胶基体中添加碳系导电填料(CB、CNT),利用超临界CO2发泡技术,制备了CB/硅橡胶、CNT/硅橡胶以及CB/CNT/硅橡胶复合导电泡沫材料,研究了混料胶料的流变行为以及发泡前后复合材料电导率、电磁屏蔽效能的变化规律。结果表明,CB与CNT均会阻碍硅橡胶复合材料的初始交联,导电填料含量越多交联越迟缓。CB/CNT/硅橡胶复配体系中更容易形成导电通路,当CB/CNT(1∶1)总含量为8%(质量分数)时,硅橡胶复合材料的电导率可达10^-5 S/cm,其电磁屏蔽效能(EI)为14~26 dB。发泡后,硅橡胶复合材料的电导率及EI值均有所下降。     

球磨对碳纳米管增强泡沫铝基复合材料压缩与吸能性能的影响

因碳纳米管（CNTs）具有优异的性能,被认为是金属基复合材料理想的增强体,因此如何制备得到CNTs增强体均匀分散的金属基复合材料一直是本领域的研究热点。本文通过原位化学气相沉积（CVD）、短时球磨和填加造孔剂的工艺成功制备了CNTs增强的泡沫铝基复合材料,着重研究了球磨过程对复合泡沫铝的微观形貌、压缩性能和吸能性能的影响规律。结果表明,随着球磨时间的延长,CNTs的分散性提高并逐步嵌入铝基体中,使复合泡沫铝的组织均匀性得到改善。相对于未球磨的含CNTs 3.0wt%的复合泡沫材料,当球磨时间增加至90 min时,复合泡沫铝的孔壁硬度、屈服强度和吸能能力分别提高了67%、126%和343%。     

Enhanced acoustic damping in flexible polyurethane foams filled with carbon nanotubes

Flexible polyurethane (PU) foams, with loading fractions of up to 0.2 wt% carbon nanotubes (CNTs), were made by free-rising foaming using water as blowing agent. Electron microscopy revealed an open cellular structure and a homogeneous dispersion of CNTs, although the incorporation of nanofiller affected the foaming process and thus the final foam density and cellular structure. The compressive response of the foams did not show an unambiguous improvement with CNT content due to the variable foam structure. However, dense films generated by hot pressing the foams indicated a significant intrinsic reinforcement of the polymer, even at low loadings of CNTs. Most significantly, CNTs were found to increase the acoustic activity monotonically at concentrations up to 0.1 wt%.     

Effective conductive properties of open-cell foams

The work is devoted to the problem of simulation of the effective electro and thermoconductive properties of open-cell foam materials with slim highly conductive ligaments. The solution of this problem depends on two small parameters: the ratio of the typical length and the cross-section size of the ligaments, and the ratio of the conductivities of the host medium and the ligaments. The principal terms of the asymptotic solutions (with respect to these parameters) for the fields inside the ligaments are obtained and used in the framework of a finite element method for the numerical simulation of the fields inside the representative volume element (RVE) of the foam material. The Laguerre tessellation procedure is applied for simulation of foam microstructures with various distributions of cell-sizes inside the RVE. Effective conductivity constants of the foams are obtained by averaging the detailed fields over the RVE. The number of cells inside the RVE for reliable calculations of the effective conductivities is indicated. Dependences of the effective conductive properties of the foams on the shapes of the ligaments and the distribution law of the cell-sizes are obtained and analyzed.     

Characterization of reinforced syntactic foams using ultrasonic imaging technique

Non-destructive evaluation of defects like voids in syntactic foam reinforced with epoxy compatible chopped strand glass fibres, employing ultrasonic C-scan immersion through transmission method, was under-taken. The results showed that in four of the five similarly processed foam samples, the voids were uniformly spread while in the fifth, which was processed by a different route, a large spread of low dense area was noticed emphasizing the influence that processing technique has on the amount of voids present in the composites.