High Purity Graphite Materials Was Prepared For Smelting Quartz Crucible

As an industrial raw material, graphite material owns a big weight in somespecial industry, especially high-tech fields, such as photovoltaic solar energy, nuclearenergy atomic energy, automobile industry, space technology, etc. While the purity ofgraphite material needed in these industries is necessarily above99.9%or even99.99%, which can hardly be fulfilled by General graphite products. Therefore, it isnecessary to research and develop high-purity graphite materials, which is the trend ofcarbon industry and makes graphite materials used in some wider and deeper domains.In the paper, with calcined petroleum coke and mid-temperature coal pitch as themain raw material, high purity graphite materials with required bulk density,resistivity and ash content are successfully made. Via experiment, the best aggregategrain size is determined; The factors of producing high purity graphite materials andthe effect of grain size on mechanical properties and electrical conductivity areexamined through process analysis and physical and chemical analysis; And thefactors of high purity graphite material structure are studied with SEM, XRD, andTG-DSC, the results obtained are as follow:(1) With1-0mm,0.5-0mm and0.15-0mm calcined petroleum coke as aggregateand mid-temperature coal pitch as binder, via the technology of “first dip thencalcination and purify”, high purity graphite materials, which can be used for quartzcrucible smelting, is prepared with bulk density of above1.65g/cm~3, even1.70g/cm~3of mid-coarse and fine structure, electrical resistivity less than10μ m and ashcontent below40ppm.(2) With0.5-0mm calcined petroleum coke as aggregate,0.075-0mm aggregateof mid-coarse graphite materials is around60%at weight at best, which make theproducts own the biggest bulk density，that is1.561g/cm~3, while lower or higher thanthe scale will detract the bulk density.(3) The grain size of calcined petroleum coke aggregate obviously influences thebulk density, mechanical strength and electrical conductivity of high purity graphitematerials. The finer structure can improve the bulk density and mechanical strengthbut debase the electrical conductivity; To the contrary, the coarser structure willenhance the electrical conductivity but detract the bulk density and mechanicalstrength. (4) When calcined petroleum coke aggregates with different grain sizes areadopted to prepare high purity graphite materials, the smaller the grain size, thestronger the thermal-erosion properity.