Effect of diluting agent Al2O3 on the combustion velocity of NiO/Al aluminothermic system and apparent activation energy calculations
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摘要: 研究了Al2O3稀释剂添加量对NiO/Al体系燃烧速度及体系产物形貌的影响, 结合绝热温度的计算结果, 基于Merzhanov等提出的燃烧波速公式, 根据体系ln(v/Tad)-1/Tad的Arrhenius图, 测定了添加Al2O3后NiO/Al体系的反应激活能。研究结果表明: 对于NiO/Al体系, 在一定范围内(0~5％, 25%~35％, 质量分数)添加Al2O3稀释剂时, 体系绝热温度与燃烧速度均不发生较大变化; 体系的反应过程受到压块内铝反应物传质过程的影响, 高于2740 K时(Al反应物沸点温度), 体系的表观反应激活能为(64±14) kJ/mol, 温度低于2740 K时, 压块内的传质过程将以毛细作用为主, 体系的反应激活能为(189±15) kJ/mol。Abstract: The effects of diluting agent Al2O3 on the combustion velocity and the products microstructure of NiO/Al aluminothermic system were studied. Combined with the adiabatic temperature calculation, the apparent activation energy of NiO/Al system were measured by Arrhenius diagram of ln(v/Tad)-1/Tad based on the combustion equation proposed by Merzhanov et al. The results show that in a certain range of Al2O3 mass fraction(0~5％, 25%~35％), the combustion velocity of NiO/Al aluminothermic system is considerable invariable. The further results show that the process of combustion is contributed to the mass-transferring of Al reactant of burning compact. When the temperature above the boiling point of Al(2740 K), the apparent activation energy of NiO/Al aluminothermic system is (64±14) kJ/mol. On the contrary, that is (189±15) kJ/mol.
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