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1.
活性中间相炭微球的制备及机理研究   总被引:2,自引:0,他引:2  
以中间相炭微球(MCMBs)为原料,采用KOH、K2CO3分别对MCMBs进行活化,比较活化效果,发现KOH是一种有效的活化剂,通过KOH活化制备出比表面积达2775 m2/g的活性炭.对活性炭进行XRD、BET比表面积与SEM分析,发现活化后MCMBs的石墨微晶结构被破坏,所制得的活性炭是由无定形组织构成的.活化机理为一系列的化学反应与钾插入石墨微品片层的共同作用.  相似文献   

2.
不同煤焦油沥青与吡啶烷的反应性能的比较   总被引:1,自引:1,他引:0  
以三种不同的煤焦油沥青为原料,分别与吡啶硼烷反应制备了硼取代中间相沥青。比较了它们的软化点、残炭值、四氢呋喃不溶物(THFI)以及中间相的偏光显微结构。发现煤焦油沥青不同所得结果有显著差别:较高软化点的沥青与吡啶硼烷的反应活性较强,而相同软化点的净化煤焦油沥青与吡啶硼烷具有更强的反应性,所得中间相沥青的软化点,残炭值及四氢呋喃不溶物的含量较高,其偏光显微结构也证实了这一点。  相似文献   

3.
选取M22、M15和M23三种不同粒径中间相碳微球(MCMBs)作为填料,分别以10vol%、25vol%、40vol%和50vol%体积分数填充氰酸酯树脂(CE)制备了MCMBs/CE复合材料,通过SEM、XRD、拉曼光谱仪、导热仪、体积电阻仪分析了不同粒径的MCMBs/CE复合材料的性能。结果表明:三种球形粉体都具有石墨化结构,其中M22粉体球形度最好、石墨化程度最高(ID/IG=0.23)、体积电阻率最小。三种MCMBs粉体制备的MCMBs/CE复合材料的吸水性、导热性和导电性均随填充量的增加而增大,冲击强度则先增大后减小。其中以M22在40vol%填充率下所得MCMBs/CE复合材料的综合性能最优,吸水率为0.45%,冲击强度为23.6 kJ/m2,热导率达1.28 W/(m·K),体积电阻率达1.5 Ω·cm。  相似文献   

4.
均四甲苯基中间相沥青纤维不熔化行为的研究   总被引:2,自引:0,他引:2  
宋怀河  刘朗  张碧江 《新型炭材料》1999,14(1):7-282326
由均四甲苯出发,通过甲醛/H+交联及进一步热处理合成了低软化点(260℃)、高H/C原子比(0.86)、富含甲基基团、分子结构呈完全渺位缩合构型的中间相沥青。研究了该中间相沥青纤维的不熔化行为,发现它呈现出与一般石油系或煤焦油系中间相沥青的不同氧化行为,虽然具有较高的氧化反应性(在150℃开始与氧反应),但要实现纤维的完全不熔化却需较多量的氧与之交联。以0.2℃·min-1(170℃~260℃)的升温速率升到260℃,恒温180min得到的不熔化纤维的氧含量达17.6%,其炭纤维强度可达2100MPa。沥青呈现高氧化反应性的原因在于体系中含有较多量的甲基、亚甲基及孤立芳氢,它们引发了氧化反应的快速;中间相沥青的渺位缩合构型分子及小芳香核片的存在是不熔化过程需要多量氧的原因。  相似文献   

5.
在过渡金属化合物氯化钴参与下低温(<1000℃)处理中间相炭微球(MCMBs),制备高容量锂离子电池的炭负极材料。Raman分析和X-射线衍射分析表明,热处理后MCMBs以低温炭结构为主,但微球表面的碳微晶尺寸较内部增大;电化学恒电流测试表明,热处理后MCMBs的可逆容量明显提高,在不降低充电容量的前提下将首次库仑效率从52.2%提高至86.7%,循环性能也得到积极改善。认为热处理后MCMBs电化学性能的提高是由于低温催化热处理使得材料表面结构更加有序化,从而阻止电解液分子的进入及发生不可逆电化学反应。  相似文献   

6.
煤焦油沥青制备中间相   总被引:3,自引:2,他引:1  
煤焦油沥青在微型高压釜中、氮气氛下,通过改变反应温度和停留时间,制取了中间相沥青(MP)。采用FTIR、偏光显微镜、XRD和SEM对MP进行了表征,表明煤焦油沥青经脱氢缩合反应转变成MP。其最佳反应条件为400℃、7h。  相似文献   

7.
中间相沥青基炭纤维具有低电阻、高导热特性,是目前最具发展前景的功能型导热、散热材料,但是国内对其微观结构和性能的研究报道较少。对国外高导热中间相沥青基炭纤维的微观结构和形貌进行了分析,同时将实验室研发的不同截面形状中间相沥青基炭纤维进行比较。研究结果表明中间相沥青基炭纤维具有的高导热特性源于其内部三维有序堆积的类石墨层状结构和较为完整生长的石墨晶体。热处理温度越高,其类石墨晶体生长越完善,层片取向程度越高。与圆形截面辐射状结构中间相沥青炭纤维相比,带状截面炭纤维有效解决了劈裂问题,其石墨片层间距为0.337nm,层片堆积高度达到26.77nm,轴向热导率高于800W/(m.K)。  相似文献   

8.
水性中间相沥青的制备研究   总被引:2,自引:1,他引:1  
以煤焦油沥青为原料,以浓硫酸和浓硝酸为氧化剂,可得到易溶于碱性水溶液的水性中间相沥青。详细考察了沥青氧化条件对水性中间相沥青收率的影响,以及水性中间相沥青的元素和官能团组成。结果发现,反应温度、浓硫酸和浓硝酸的比例对水性中间相沥青收率影响存在一优化值,而反应时间、浓硫酸和浓硝酸的用量对水性中间相沥青收率先是线性的,当达到一定值后水性中间相沥青的收纺基本恒定。水性中间相沥青的组成是复杂的,根据其中化合物含氧官能团的数量和性质,它们可分别在不同pH值条件下制备而得。  相似文献   

9.
采用中间相沥青微粒在旋转式反应釜中与氟气进行反应制备出氟化沥青.红外测试表明:随着氟化反应的进行,C-H键消失,C-F键形成并逐渐增加;XRD测试表明:中间相沥青中原有的大分子平面芳烃结构被破坏.生成的氟化沥青随F/C比的提高,层间距逐渐增加,分子结构转变为类似于氟化石墨椅子状的结构.  相似文献   

10.
过滤后的煤焦油沥青分别与一、二、三、四苯基硅烷在1MPa氩气气氛和420℃~460℃温度下共碳化,合成了硅取代聚芳烃中间相,在四种合成中间相中,元素硅的起始加入量均为2%,测定了裂解残留物和硅的收率,可溶性,玻璃转代温度以及裂解残留物的炭收率;并分别以偏光显微镜和电子探针微分析法考察了残留物的微结构和相应的硅分布,硅的收率取决于不同的苯取代硅烷的挥发性和反应性。裂解残留物显示出三种不同的共存相:(a)含有粗镶嵌织构和痕量硅的光学各向异性相;(b)硅含量较高的光学各向同性相;(c)含细镶岩织构和中等硅含量的光学各向异性相。最后这种中间相主要来自二,三苯取代硅烷与煤沥青的共炭化,是由于硅取代聚芳烃中碳原子并破坏了其分子的平面结构而引起的。  相似文献   

11.
为考察中间相的形成和生长机理,将一种煤沥青制备的中间相炭微球添加到另一种沥青中进行二次热缩聚,结果发现中间相炭微球可以进行二次生长。二次热缩聚中间相炭微球的产率、粒径分布、表面和断面的形貌表明添加的中间相炭微球对于沥青热缩聚过程的物理作用更为主要;二次热缩聚过程包含了添加的中间相炭微球的二次生长过程和原料沥青独立成核生长两个相互竞争的过程,中间相炭微球的添加量对这两个过程有着重要的影响;中间相炭微球的生长是基本构筑单元不断进入相界面的构筑过程。  相似文献   

12.
A facile and cost-effective method which combines supercritical CO2 and micro-jet exfoliation has been developed for producing graphene nanosheets with high-quality. CO2 molecules can intercalate into the interlayer of graphite because of their high diffusivity and small molecule size in supercritical operation. The tensile stress induced by graphite interfacial reflection of compressive waves exert on the graphite flakes, which lead to further exfoliation of graphite. Scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM), Raman spectrum and X-ray diffraction (XRD) are used to identify morphology and quality of the exfoliated graphene nanosheets, which reveal that the graphite was successfully exfoliated into graphene and more than 88% of graphene nanosheets are less than three layers. The yield of graphene nanosheets is about 28 wt% under optimum conditions, which can be greatly improved by repeated exfoliation of the graphene sediment. The pure graphene film has a high conductivity of 2.1 × 105 S/m.  相似文献   

13.
By adding carbon nanotubes (CNTs) into medium temperature coal tar pitch, mesocarbon microbeads (MCMBs) were obtained via thermal condensation, then CNTs/MCMBs composites were in situ prepared using compression molding. The morphology, structure and mechanical properties of CNTs/MCMBs composites were characterized by optical microscope, digital camera, scanning electron microscope (SEM) and mechanical test machine. Results showed that CNTs were used as the nucleating agent and could inhibit the growth and coalescence of MCMBs. The optical textures of CNTs/MCMBs composites showed similar characteristics to the thermal condensation products from coal tar pitch with CNTs. The mass ratio of CNTs to coal tar pitch played an important role in the mechanical properties of CNTs/MCMBs composites. The density and bending strength of CNTs/MCMBs composite first increased and then decreased with the increase of the proportion of CNTs. When the proportion of CNTs was 5 wt%, the density of the composite reached the maximum (1.76 g/cm3). In addition, the bending strength of the composite reached the maximum (79.6 MPa) as adding 2 wt% CNTs into coal tar pitch.  相似文献   

14.
通过控制吡啶的抽提次数得到一系列不同β树脂含量的沥青中间相炭微球,并在SEM下观察其微观形态,结果表明随着抽提次数的增加,β树脂含量越来越低,并且微球分散越均匀。用这样得到的中间相炭微球在一定条件下热压成型制得各向同性炭块,生坯的弯曲强度随着β树脂含量的降低也逐渐降低,但炭化后炭块的弯曲强度随β树脂含量有一个4极大值,说明要取得性能良好的整体炭块,需要有一个最佳的β树脂含量。  相似文献   

15.
This study examined the effects of the mechanical milling conditions on the hydrogen adsorption behaviors of graphite flakes under different gas streams. A ball mill technique with various gas streams during treatments was used to introduce oxygen-containing functional groups on the graphite surfaces. The structural properties of graphite were evaluated by XRD, and the surface properties and textural properties were observed SEM, FT-IR, XPS and N2/77 K adsorption isotherms. The hydrogen adsorption behavior of the graphite flakes were evaluated using a volumetric method at room temperature and 100 atm. The mechanically-milled graphite flakes under an oxygen stream showed a higher concentration of oxygen functional groups and greater hydrogen adsorption capacity than that of graphite flakes under an argon stream. This suggests that oxygen functional groups have good chemical affinity with hydrogen molecules in this system.  相似文献   

16.
《Advanced Powder Technology》2019,30(11):2759-2767
The present study reports the microstructural and morphological changes during high energy ball milling of Cu with Ag and Graphite flakes. XRD patterns of ball milled Cu-Ag showed a reduction in the intensity of Ag peaks (1 1 1) and an increase in the lattice parameter of Cu. With an increase in milling time, the formation of metastable Cu-Ag solid solution was observed. Lattice parameter values for 40 h milled Cu (3.6169 Å) and Cu-GF composites (3.6166 Å) indicated that C does not dissolve in Cu. The lattice parameter of Cu in milled Cu-Ag-graphite flake was lower compared to milled Cu-Ag mixture indicating that graphite flakes inhibit solid solution formation. Raman spectra revealed that graphite flakes were converted into multilayer graphene after 10 h of milling. The crystallite size of Cu in the milled powders decreased with increase in milling time and reached a value of ∼25 nm after 35 h of milling. The lattice strain also increased with milling time. The D10, D50 and D90 size reduced appreciably after 5 h of milling.  相似文献   

17.
Synthesizing diamond single crystal by diamond seed particles which were electroplated with nickel film as catalyst under high pressure and high temperature (HPHT) was described. The microstructure of nickel film after synthesis and morphology of grown diamond were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The phase structure in nickel film were graphite, NiC, Ni, and diamond structure hadn't been found. A lot of recrystallized graphite pits appear in interface between the inner surface of nickel film and the surface diamond. It is shown that the new-grown diamond was developed epitaxially on the crystal planes of seeds. Also, the new-grown diamond grew by two-dimensional nucleation and by a layer growth mechanism. The growth process of crystal was microaggregate→step→expansion→new crystal layers, and the flat growth interface transformed into a cellular interface at the same time.  相似文献   

18.
采用化学镀的方法在石墨化中间相炭微球的表面镀覆金属镍,采用扫描电镜对镀覆后的炭微球进行了表面分析,采用X-射线衍射的方法对镀镍炭微球进行了物相分析,将镀覆后的中间相炭微球用于锂离子电池负极材料,并进行了不同倍率的充放电分析及交流阻抗研究。结果表明,在不使用活化剂和敏化剂的情况下,金属镍仍然能够沉积在炭微球的表面;炭微球的大电流放电性能大大提高,在2C放电电流下的放电容量提高了23%,镀镍后交换电流密度增大并且SEI膜电阻减小,炭微球的反应活性大大提高。  相似文献   

19.
This paper reports a facile solution route (water bath heating or hydrothermal heating) for synthesizing a few Sb-based self-assembly structures including bundles of nanowires, nanowire-flowers, long nanowires, bundles of flakes, nanobelts, hollow prisms. These obtained nanomaterials were characterized by XRD, FE-SEM, TEM, SAED, and HRTEM. It was found that the morphology, size and phase of self-assembly nanostructures were strongly dependent on reaction temperature, reaction time, pH value, and heating source. In particular, nanowire-flowers and hollow prisms of antimony oxide or oxychloride have not been reported previously. A possible mechanism based on stepwise nucleation and aggregation of nanowires or flakes was also proposed.  相似文献   

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