Highly stable nanocarbon supported Pt catalyst for fuel cell via a molten salt graphitization strategy

Proton exchange membrane fuel cells (PEMFCs) durability has been severely hindered by carbon support poor stability in the cathodic Pt-based catalyst. Herein, a high-surface-area nitrogen-doped graphitic nanocarbon (N-G-CA) with mesopores is developed as Pt support to address PEMFCs durability challenge. Resorcinol-formaldehyde aerogel pyrolyzed carbon aerogel is selected as N-G-CA raw material. Nitrogen atoms are introduced into carbon aerogel via NH₃ heat treatment. Then, nitrogen-doped carbon aerogel is transferred into N-G-CA via heating together with transition-metal salts (one of FeCl₃, FeCl₂, CoCl₂, or MnCl₂, etc.) at 1200 °C. As ORR catalyst, Pt/N-G-CA half-wave potential only lost 10 mV, after 30, 000 cycles accelerated aging test in the rotating-desk-electrode. Only 12 mV voltage loss at 1.5 A/cm2 is observed, after 5, 000 cycles for membrane electrode. Pt/N-G-CA exhibits superior durability and activity than commercial Pt/C. High durability of Pt/N-G-CA is due to N-G-CA high graphitization extent, as well as the interactions between doping nitrogen and Pt. N-G-CA is promising as stable support for durable Pt-based catalysts in PEMFCs, thanks to enhanced carbon corrosion resistance, uniformly dispersed Pt, and strong support-metals interaction.     

碳纳米管表面处理技术的研究

对催化裂解法制备的碳纳米管（CNTs)分别进行了酸处理，高温石墨化及酸处理结合高温石墨化的综合处理。利用透射电镜，拉曼光谱仪，红外光谱仪等手段对处理前后的CNTs进行了分析。结果表明，石墨化和酸煮对CNTs表面的去除非晶碳，提高晶态化程度的作用都具有明显的效果，而2种方法相结合则对碳纳米管晶化程度的提高作用效果更加显著。     

大型风电球墨铸铁件的生产实践

以轮毂为例,介绍对大型风力发电机球墨铸铁件生产工艺进行的试验研究。通过优化铸型工艺,采用适当的浇注系统和低温石墨化退火工艺,选择合理的化学成分,控制球化处理与孕育处理,可生产出各项性能指标合格的风电铸件。     

石墨化率不同的自焙炭块的热膨胀

采用精密垂直拉杆膨胀仪在１４～１０００℃范围内测量了具有不同石墨化率的自焙炭块的相对热伸长量，并由此获得了热线膨胀系数α。结果表明：石墨化率一定时，α值在较低温度下随温度升高而增加，在较高温度下，α值随温度变化不明显；恒温时，石墨化率越高，α值越低。讨论了单位热应力下的弹性模量概念     

Evolution with heat treatment of crystallinity in carbons

The variation with heat treatment of the dimensions L_a and L_c of the graphite-like crystallites of graphitizable and non-graphitizable carbons is studied. The increases of L_a and L_c with heat treatment temperature (HTT) owing to three processes (crystallite growth in-plane, coalescence of crystallites along the c-axis and coalescence of crystallites along the a-axis) are functionally separated. The evolution with HTT of the number of crystallites (N_cr), the mean volume of the crystallites (v_cr) and the total volume occupied by the crystallites (V_cr) are determined in terms of the changes of L_a, L_c and d₀₀₂. Since among other characteristics the crystallites form the electrical and thermal conducting phase of the carbon, N_cr, v_cr and V_cr are important parameters in many physical properties of these materials. The developed expressions were applied to a non-graphitizable and to a graphitizable carbon.     

不同炭化压力下沥青炭结构特性的研究

将高温煤沥青和浸渍剂沥青在不同压力下炭化，在2500℃下对所得沥青炭进行石墨化处理；测试了所得沥青炭的体积密度、开孔率；利用扫描电子显微镜（SEM）观察了所得沥青炭的显微结构；利用XRD检测了不同炭化压力所得沥青炭石墨化处理后的石墨化度。结果表明：随着炭化压力的增大．沥青炭的体积密度增大而开孔率减小；随着炭化压力的增大沥青炭显微结构有从流线型向镶嵌型和域型转变的趋势：流线型结构沥青炭石墨化度较高；沥青中QI组分也会影响沥青炭的显微结构。     

商业化的锂离子电池石墨负极材料的研究进展

综述了锂离子电池石墨负极材料的研究进展,对MCMB、天然石墨与人造石墨、炭纤维为代表的石墨负极材料目前的研究和应用现状进行了详细的论述,并对石墨类炭负极的发展作了展望。     

Effects of iron catalyst on the formation of crystalline domain during carbonization of electrospun acrylic nanofiber

To investigate the effects of introducing the iron compound on the carbonization behavior polyacrylonitile (PAN)-based electrospun nanofibers were carbonized with or without iron(III) acetylacetonate (AAI) over the temperature range of 900–1500 °C in nitrogen atmosphere. The morphological characteristics of the carbon nanofibers were investigated using X-ray diffractometer (XRD), Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The electrical conductivity of the carbon nanofiber web was measured by four-point probe method. The iron catalyst had a profound effect on the crystal structure of the carbonized nanofiber. In the presence of AAI the nanofibers carbonized at 1300 °C developed graphite structure, which could be obtained at the temperature higher than 2000 °C in the absence of the catalyst. The in-plane size of the graphite crystals (L_a) was measured to be about 6.5 nm by Raman spectroscopy and the (0 0 2) spacing by XRD was 0.341 nm.     

试论Si促使铁液凝固过程中石墨化的机理

Si促使铁液凝固过程中不断G化,奥氏体(A)共析分解为F+G的机理分析认为:铁碳合金凝固以稳定状态转化,是Si熔于铁液中的化学特性,不断促使铁液的C溶解度下降所形成G的速度>凝固时铁液C的变化速度的必然结果。铁液凝固的过冷度,随Si的提高,过冷度是减少的,是Si对铁碳合金物理性能产生的影响之一,与C的G化无关,不能与Si的化学特性混为一谈,也不能作为促进铸铁G化退火的依据。     

碳滑板材料石墨化度XRD和Raman光谱研究

采用显微激光拉曼光谱及X射线电子衍射测量，摘要选用进口和国产滑板材料作为对比材料，并进行高温烧结处理。分析了试样的形貌和结构，并表征了不同碳滑板材料在高温烧结前后的结构参数。结果表明，两种表征方法的结果存在一致性；进口碳滑板材料的石墨化度高于国产滑板，且两种滑板材料都有不同的石墨相组成，不同相的石墨化度也不同；经过高温烧结处理，滑板材料的石墨化度提高。