生沥青焦颗粒尺寸对自烧结石墨块体微观结构和性能的影响

Effect of the average grain size of green pitch coke on the microstructure and properties of self-sintered graphite blocks

由不同颗粒尺寸(5.1、3.1和1.9μm)的生沥青焦制得3种自烧结石墨块体,并对其进行系统的分析表征。石墨块体的结构和性能随着生焦颗粒尺寸的减小呈现出规律性变化。石墨块体的密度、机械强度、肖氏硬度和热膨胀系数随着生焦颗粒尺寸的减小而提高,石墨化度、晶粒尺寸、热导率、平均孔径和孔隙率随着生焦平颗粒尺寸的减小而降低。石墨块体的平均孔径均在纳米尺度,能有效地阻隔熔盐浸渗而应用于熔盐反应堆中。此外,石墨块体因其密实结构和相对优异的机械性能,在密封领域也有较大的应用潜力。自烧结石墨块体的微观结构和性能与生焦颗粒尺寸关系密切,并讨论了生焦颗粒尺寸对石墨块体微观结构/性能的影响及石墨块体微观结构与性能间的关系。

Three self-sintered graphite blocks(SGs)were prepared from green pitch cokes with different average grain sizes(5.1,3.1 and 1.9μm)using cold isostatic compaction.The microstructures and properties of the SGs were characterized by XRD,SEM,mercury porosimetry,mechanical and thermal tests.Results indicated that the microstructures and properties of the SGs were closely related to the green coke granularity.When decreasing the average grain size of the green coke from 5.1 to 1.9μm,the density,mechanical properties,Shore hardness and coefficient of thermal expansion increased while the degree of graphitization,crystallite diameter,thermal conductivity,median pore diameter and porosity decreased.The median pore diameters of the SGs were all in the nanometer range,which implied that they could effectively inhibit the infiltration of molten salt and might be used in molten salt reactors.