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用煅烧石油焦作填料、煤沥青作粘结剂、锆粉作添加剂,采用热压工艺制备了一系列不同质量配比的掺杂锆再结晶石墨。考察了不同质量配比的添加锆对再结晶石墨的热导率、电阻率和抗折强度的影响以及微观结构的变化。实验结果表明,与相同工艺条件下制备的纯石墨材料相比较,掺杂锆再结晶石墨的导热、导电以及力学性能均有较大的提高。当锆掺杂量为6wt%时,再结晶石墨电阻率有明显的降低;而当锆掺杂量超过6wt%时,对再结晶石墨的电阻率影响不大。室温下,RG-Zr-12再结晶石墨的层面方向热导率可达410W/(m·K)。微观结构分析表明,随着锆掺杂量的增加,石墨微晶的石墨化度以及微晶尺寸增大,晶面层间距降低。原料中掺杂锆量为12wt%时,再结晶石墨的石墨化度为97.7%,微晶参数La为475nm。XRD及SEM分析表明,锆元素在再结晶石墨中以碳化锆的形式存在。锆对再结晶石墨制备过程的催化作用可以用液相转化机理来解释。
Using calcined petroleum coke as filler, coal tar pitch as binder and zirconium powder as additive, a series of doped zirconium recrystallized graphite with different mass ratios were prepared by hot pressing process. The effects of zirconium addition on the thermal conductivity, resistivity and flexural strength of recrystallized graphite and the changes of microstructure were investigated. The experimental results show that the thermal conductivity, electrical conductivity and mechanical properties of the doped zirconium recrystallized graphite are greatly improved compared with pure graphite materials prepared under the same process conditions. When the doping amount of zirconium is 6wt%, the resistivity of recrystallized graphite decreases obviously. When the doping amount of zirconium exceeds 6wt%, the resistivity of recrystallized graphite has little effect. The room-temperature thermal conductivity of RG-Zr-12 recrystallized graphite can reach 410 W / (m · K) at room temperature. Microstructure analysis shows that with the increase of zirconium doping, the degree of graphitization and the crystallite size increase and the interplanar spacing decreases. When the amount of zirconium doping in the raw material is 12 wt%, the graphitization degree of the recrystallized graphite is 97.7% and the crystallite parameter La is 475 nm. XRD and SEM analysis showed that the zirconium element existed in the recrystallized graphite as zirconium carbide. The catalytic effect of zirconium on the recrystallization graphite preparation can be explained by the mechanism of liquid phase transformation.