With the advancement of economy and society and the increment of normal asset utilization,people gives increasingly more consideration to the improvement of energy equipment with low price,long cycle life and high power density.More and more attention has been paid to biomass-based porous carbon supercapacitors.Using biomass tar as a precursor,a one-step carbonization and activa-tion method was adopted to prepare carbon materials.In this paper,the morphology and structure of porous carbon were characterized by SEM and BET,the effects of the proportion of activator to carbon,activation temperature and activation time on the microstructure and electrochemical properties of biomass tar-based porous carbon were investigated.When the activation temperature is 700℃,the activation time is 1.5 hours,and the ratio of potassium hydroxide to biomass tar is 2∶1,a porous carbon material with the specific sur-face area of 2137.3 m2·g-1 was obtained.When used as the electrode for supercapacitor,the porous carbon electrode shows a capaci-tance of 276.2 F/g at the current density of 1.0 A/g.When the current density is increased from 0.1 A/g to 5.0 A/g,the FC700-2-1.5 has a high capacitance retention of 74.02%.In this work,the activated carbon for the supercapacitor was made from biomass waste,and it is a novel approach to achieving high-value utilization of biomass waste.
石墨是制备高温气冷堆球形燃料元件的主要和关键原材料.高温气冷堆球形燃料元件用核级石墨粉包括天然石墨粉和人造石墨粉.微观结构深刻影响粉体的物化性能,物化性能则进一步影响基体石墨粉和球形燃料元件的加工工艺,本文详细介绍了高温气冷堆球形燃料元件用核级天然石墨粉和人造石墨粉的特性、微观结构及制备工艺.
高温提纯是获得超高纯石墨的重要手段,分析高温提纯过程中杂质成因与杂质析出机制具有重要意义.本文将浮选石墨经酸洗提纯后,采用高温纯化方式进行再提纯.通过对高温提纯前后的石墨和炉内外收集的杂质进行化学成分、显微形貌和物相组成分析,研究了高温提纯过程中的杂质析出机理和炉内杂质形成原因,为天然石墨的高温提纯工艺优化提供了重要参考.
通过电镀法在材料表面生成镀铜层来提高导热炭材料力学性能,用扫描电子显微镜、万能材料试验机、激光热导率仪分析了炭-铜复合结构的表面形貌、弯曲强度和导热性能,研究了电流密度对镀层形貌和厚度的影响,以及不同镀层厚度对力学性能和导热性能的影响.验证了表面镀铜可以有效提高导热炭材料的力学性能,电流密度在1.5～2.0A·dm-2可以得到光亮平整的镀层;导热炭材料初始热导率为567 W·m-1·K-1,当镀层厚度为20 μm,弯曲强度提高61.5％,热导率为560W·m-1·K-1;当镀层厚度为40 μm,弯曲强度提高84.6％,热导率为524 W·m-1·K-1.
采用耐高温粘接剂对C/C复合材料进行粘接,粘接剂的粘接厚度分别为175,260,355,445 μm,通过对粘接C/C复合材料剪切强度测试和SEM分析,研究了胶层厚度对C/C复合材料剪切粘接性能的影响规律.结果表明,胶层厚度为175 µm时剪切粘接强度为13.22 MPa,胶层结构均匀致密,无孔隙缺陷,胶层厚度增加至445pm时剪切粘接强度为10.82 MPa,降低了 18.15％.通过SEM对不同厚度胶层微观结构分析表明,胶层厚度为175μm的粘接剂微观结构均匀致密,没有孔洞、裂纹等缺陷.胶层厚度增加至445 µm后,粘接剂中出现直径约250 pm的凹坑、直径约100～200 μm的大孔以及直径约5～50 μm的小孔,剪切粘接强度降低18.15％.分析其原因为胶层厚度增加,固化和炭化过程中胶层内部的气泡含量逐渐增多,体积收缩概率增大,孔隙等缺陷形成,而孔隙的形成会导致材料的有效承载面积减小,引起应力集中,粘接强度降低.
