A3-3基体石墨的氧化行为

The oxidation behavior of A3-3 matrix graphite

    摘要
  • 摘要: 采用自行搭建的热重实验平台对798~973 K温度范围内温度对A3-3基体石墨的氧化行为进行研究,氧化剂为100 mL/min的空气。不同温度下石墨试样均被氧化至失重10%~15%。结果表明,基体石墨的氧化速率(OR)随着温度的升高显著提升,温度为973 K时基体石墨的OR约为798 K时的70倍。虽然973 K时氧气供给速率与平均碳消耗速率的比值仅为4.3,但石墨OR的Arrhenius曲线依然保持了很好的线性关系,表明该温度下基体石墨的氧化机理没有发生改变。在798-973 K温度范围内,A3-3基体石墨在空气中的氧化均处于化学区,其活化能为176 kJ/mol,Arrhenius氧化方程可描述为:OR=2.9673×108·exp(-21124.8/T),单位为wt%/min。与堆内的核级结构石墨相比,基体石墨的活化能相对较低,说明基体石墨在空气中更易被氧化,这主要跟基体石墨中含有未完全石墨化的树脂炭有关。

     

    Abstract: The effects of temperature on the oxidation behavior of the A3-3 matrix graphite(MG) in the temperature range 798-973 K in air with a flow rate of 100 mL/min to burn-offs of 10-15 wt%, were investigated by a home-made thermo-gravimetric experimental setup. The oxidation rate(OR) increases significantly with the temperature. The OR at 973 K is over 70 times faster than at 798 K. The oxidation kinetics of A3-3 MG in air at temperatures up to 973 K is in the reaction control regime, where the activation energy is 176 kJ/mol and the Arrhenius equation could be described as:OR=2.9673×108·exp(21124.8/T) wt%/min. The relatively lower activation energy of MG than that of structural nuclear graphite indicates that MG is more easily oxidized.

     

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