Combustion synthesis of C/MgAl2O4 composite powders using magnesium oxalate as carbon source

In order to solve the bottleneck problems including uniform distribution, and oxidation resistance of nano carbons in oxide ceramics, C/MgAl₂O₄ composite powders were prepared with MgC₂O₄·2H₂O, MgO₂, Al₂O₃, and Al as raw materials via combustion method under argon atmosphere. The maximum adding amount of MgC₂O₄·2H₂O 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 MgAl₂O₄ and carbon. The prepared MgAl₂O₄ has granular and rod-like morphologies, and the free carbon (1.172 wt%) exists between particles of MgAl₂O₄. Moreover, the addition of FeC₂O₄ 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/MgAl₂O₄ composite powders was calculated as 143.01 kJ/mol which was 22.17% higher than that of carbon black/MgAl₂O₄ powders (117.06 kJ/mol), suggesting that the C/MgAl₂O₄ composite powders prepared by combustion synthesis have excellent oxidation resistance.