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In this study, based on self-reactive quenching technique, hollow ceramic microspheres (HCMs) containing barium ferrites were synthesized using Al+Fe2O3+BaO2+sucrose+ epoxy resin as the reactive system and polyethylene glycol (PEG) as the foaming agent. The influence of PEG on the particle size and microwave absorption properties of HCMs is investigated using SEM, XRD, laser particle size analyzer and vector network analyzer. Preliminary results show that the average particle size increases initially from 28 μm to 53 μm after adding PEG, as well as the particle distribution gets narrower and the surface takes on classical hexagonal crystals. BaFe2O4, the intermediate phase of M-type barium ferrites (BaFe12O19), can be seen in XRD. The microwave absorption properties are improved greatly in the frequency range of 8–18 GHz. And the minimum reflection loss can reach −10 dB.

The self-reactive quenching technology, which combines flame thermal spraying technology, self-propagating high-temperature synthesis (SHS), and rapid solidification, is a new method for preparation of hollow microspheres. Based on this, the effect of heat released by different exothermic systems on preparation of hollow ceramic microspheres was studied. The results show that for low-exothermic system Si-Sucrose-NH4Cl, the self-propagating reactions cannot occur, and the quenching products are Si microspheres with porous structure. For the moderate exothermic system Al–SiO2-Sucrose, the quenching products consist of some grains, which are hollow spherical or nearly spherical particles and irregular powders. Formation of Al2O3–Si indicates possible occurrence of SHS reactions. Meanwhile, for high-exothermic system Al–Cr2O3-Sucrose-Si-Epoxy Resin, the quenching products consist of internal hollow spherical grains and irregular-shaped porous particles; the phase composition mainly contains Al2O3, Cr3C2, Cr7C3, Cr3Si, and mullite, showing completeness of SHS reactions. The higher the adiabatic combustion temperature of the system is, the more heat it releases is higher, and the ceramic droplets form easilier.