【摘要】 将不同量的中间相炭微球(MCMB)引入煤沥青后经过二次生长、融并和中间相重排,制备出层状结构良好和性能优异的针状焦(NCs)。用偏光显微镜观察和分析了所得中间相和半焦组织的结构;用X射线衍射仪和扫描电镜分析了NCs的微观结构;用高精度电阻率测试仪测试了电阻率;用热机械分析仪测定了热膨胀系数。结果表明:加入适量的MCMB有利于提高焦的有序性,促进针状焦石墨片层结构的形成,显著降低针状焦的电阻率和热膨胀系数值;MCMB的添加量(质量分数)低于50%时,NCs结构有序性随着添加量的提高而提高;MCMB的添加量超过50%,则焦的质量下降。MCMB的添加量为50%时电阻率和热膨胀系数值(0°～100℃)分别降低27.9%和45.7%,石墨化度提高46.2%。更多还原

【Abstract】 Needle-cokes(NCs) were synthesized via a two-step process, namely mesocarbon microbeads(MCMB) were firstly blended with coal tar pitch(CTP) at 180 oC for ca 30 min, and which was then calcined in an autoclave filled with 0.5 MPa nitrogen at 1500 oC for 5 h. The microstructure of mesophase, semi-cokes and the final product NCs was characterized by means of polarizing microscope, XRD and SEM. The resistivity and coefficient of thermal expansion(CTE) were measured by resistivity meter and thermal mechanical analyzer, respectively. The results show that the addition of moderate amount of MCMB could affect the formation of NCs, so that promote the formation of graphite-like layered structure,which significantly reduced the resistivity and CTE value of NCs. The structure of needle-cokes could be effectively improved with the increase of MCMB content(≤50 mass fraction%). However, the quality of needle-cokes began to decline as the content of MCMB exceeded 50%. The resistivity and CTE value(at0-100oC) of NCs decreased by 27.9% and 45.7%, respectively, when the content of MCMB is 50% in feedstock, meanwhile, the corresponding graphitization degree increased by 46.2%, as comparing with the parent needle-coke.更多还原