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过程工程学报 ›› 2021, Vol. 21 ›› Issue (3): 323-331.DOI: 10.12034/j.issn.1009-606X.220030

• 材料工程 • 上一篇    下一篇

多晶硅生产用煤基高纯石墨性能及应用

王启立1*， 张锋涛1， 高晓峰1， 胡建文2   

  1. 1. 中国矿业大学煤炭加工与高效洁净利用教育部重点实验室，江苏 徐州 221116 2. 成都润封电碳有限公司，四川 成都 611430
  • 收稿日期:2020-01-18 修回日期:2020-05-22 出版日期:2021-03-22 发布日期:2021-03-23
  • 通讯作者: 王启立 wqlcumt@126.com
  • 基金资助:
    中央高校基本科研业务费专项资金;徐州市重点研发计划

Properties and application of coal-based high purity graphite in polysilicon preparation

Qili WANG1*, Fengtao ZHANG1, Xiaofeng GAO1, Jianwen HU2   

  1. 1. Key Laboratory of Coal Processing and Efficient Utilization, Ministry of Education, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China 2. Chengdu Runfeng Electric Carbon Co., Ltd., Chengdu, Sichuan 611430, China
  • Received:2020-01-18 Revised:2020-05-22 Online:2021-03-22 Published:2021-03-23

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摘要： 本工作以煤焦颗粒和高温煤沥青为原料制备高纯石墨，测试并分析了其微观结构和主要物理性能，将其应用于多晶硅制备工艺的还原炉，发挥夹持硅芯、有效导电和传热作用，探索提升还原炉内生产可靠性和石墨组件复用率的措施。结果表明，高纯石墨试样结构总体较光滑，在不同尺度下局部和整体均展现出良好的结构相似性。制备的高纯石墨材料具有突出的物理性能，体积密度为1.84~1.88 g/cm3，肖氏硬度为55.2~62.4 Hs，抗折强度为33.9~45.6 MPa，抗压强度为66.3~78.8 MPa，热膨胀系数为3.76×10–6/℃~4.08×10–6/℃，电阻率为8.92~11.98 μΩ?m，灰分含量为133~202 mg/kg，各项指标表现优异。根据元素成分分析，碳元素占主体，含量为88.71wt%~90.57wt%，原子含量为92.09at%~93.25at%。除了基体碳元素外，其他元素主要有O, S, Si和Al，O的质量含量为7.15wt%~9.79wt%，原子含量为5.61at%~7.57at%。除C, O两种元素外，其他元素含量均较低，原子含量均低于1at%。通过分析还原炉中硅芯因导电不均质和热量集中引起的“亮点”和“倒棒”现象，优化石墨组件结构，将石墨帽的复用率从5.85%提升至7.28%，石墨座的复用率从7.95%提升至9.01%，倒棒率从14.22%降为4.43%，有效地保障了还原炉内安全生产，降低了硅棒废品率和生产成本，展示了煤基高纯石墨在硅晶材料制备领域的良好应用前景。

关键词: 煤基原料, 高纯石墨, 多晶硅还原炉, 石墨组件

Abstract: High-purity graphite was prepared from coal coke particles and high-temperature coal pitch, and its micro-structure characteristics and physical properties were measured and analyzed. High-purity graphite was used in the reduction furnace of the polysilicon preparation, which played the role of clamping the silicon rods, conducting electricity and transferring heat. Measures to improve production reliability and reuse rate of the graphite assembly in the reduction furnace were discussed. The results showed that the structure of the high-purity graphite samples was relatively smooth in general, and exhibited good similarity overall structure at different scales. The prepared high-purity graphite materials had outstanding physical properties: the bulk density of 1.84~1.88 g/cm3, the shore hardness of 55.2~62.4 Hs, the flexural strength of 33.9~45.6 MPa, the compressive strength of 66.3~78.8 MPa, the thermal expansion coefficient of 3.76×10–6/℃~4.08×10–6/℃, the electrical resistivity of 8.92~11.98 μΩ?m, and the ash content of 133~202 mg/kg, respectively. All the parameters of the samples were excellent. From the analysis of elemental composition, carbon element is the absolute main body, its weight content was between 88.71wt%~90.57wt%, and its atomic content was between 92.09at%~93.25at%. In addition to the matrix carbon, other elements are mainly O, S, Si, and Al. The weight content of O was between 7.15wt% and 9.79wt%, and the atom content was between 5.61at% and 7.57at%. Except for C and O, the content of other elements was lower, and the atomic content was lower than 1at%. In addition, the phenomenon of “bright spot” and “collapse of the silicon rod” in reduction furnace applications due to heterogeneous conductivity and heat concentration in the silicon cores was analyzed. By optimizing the structure of the graphite assembly, the reuse rate of the graphite cap was increased from 5.85% to 7.28%, the reuse rate of the graphite seat was increased from 7.95% to 9.01%, and the collapse rate of silicon rods was reduced from 14.22% to 4.43%. Consequently, the safe production in the reduction furnace was more effectively improved, the reject rate and the production cost of silicon rods were reduced, which demonstrated good application prospects of the coal-based high purity graphite in the field of the preparation of polysilicon.

Key words: coal-based raw materials, high purity graphite, polysilicon reduction furnace, graphite assembly