膨胀石墨的尺寸效应

以不同产地、不同粒度的鳞片石墨为原料, 采用硫酸、硝酸、高锰酸钾的适当配比为氧化剂制备膨胀石墨, 发现石墨膨胀倍数从粒度>420μm的750mL/g减小至95～85μm的110mL/g. 电镜及压汞法观察膨胀石墨的形貌及微孔的特征, 表明膨胀石墨的孔隙大小随粒度减小而减小, 反映出膨胀石墨存在尺寸效应.不同粒度的膨胀石墨的灰分、硫分和对机油的吸附能力不同, 与不同粒度膨胀石墨制备的柔性石墨板的抗拉强度也不同. 这种效应源自石墨的结晶程度的不同.

Size Effect of Expanded Graphite

Expanded graphite (EG) was prepared by using natural flaky graphite as raw material which was from different producing area and with different particle sizes, and by using sulfuric acid, nitric acid, potassium permanganate mixture of certain compounding ratio as oxidant. The results show that the expansion ratio of EG decreases from 750mL/g when the particle size is larger than 420μm to 110mL/g when the particle size is 95--85μm. Observing and determining the pore structures in EG by using SEM and mercury porosimetry, it is found that the size of macrostructures and sub-microstructures decreases along with the decrease in particle sizes. The size effect mainly results from the difference in the crystallization degree of graphite, and it is reflected in the ash content, sulfur content, adsorptivity of EG,tensile strength of compressed EG sheet.