Combustion synthesis of C/MgAl ₂ O ₄ composite powders using magnesium oxalate as carbon source

Abstract In order to solve the bottleneck problems including uniform distribution, and oxidation resistance of nano carbons in oxide ceramics, C/MgAl ₂ O ₄ composite powders were prepared with MgC ₂ O ₄ ·2H ₂ O, MgO ₂ , Al ₂ O ₃ , and Al as raw materials via combustion method under argon atmosphere. The maximum adding amount of MgC ₂ O ₄ ·2H ₂ O is 34.34 wt%. The phase compositions and microstructures of combustion products were characterized through X‐ray diffraction ( XRD ), scanning electron microscope ( SEM )/ EDX , and Raman spectroscopy. The results showed that the phases of products are mainly composed of MgAl ₂ O ₄ and carbon. The prepared MgAl ₂ O ₄ has granular and rod‐like morphologies, and the free carbon (1.172 wt%) exists between particles of MgAl ₂ O ₄ . Moreover, the addition of FeC ₂ O ₄ as catalyst in raw materials ratio would be beneficial for improving crystallization of in situ carbon generated in the products. The oxidation activation energy of the prepared C/MgAl ₂ O ₄ composite powders was calculated as 143.01 kJ/mol which was 22.17% higher than that of carbon black/MgAl ₂ O ₄ powders (117.06 kJ/mol), suggesting that the C/MgAl ₂ O ₄ composite powders prepared by combustion synthesis have excellent oxidation resistance.