Effect of annealing on electromagnetic performance and microwave absorption of spherical cobalt particles

To study the effect of annealing on electromagnetic performance, spherical cobalt particles were synthesized through a simple liquid reduction method, and then the cobalt particles were annealed at 600 °C for 1 h. The effects of annealing and mass ratios on the electromagnetic performance and microwave absorption properties were investigated based on uniformly dispersing cobalt particles in a paraffin matrix. It can be seen that annealing could improve the real part of permittivity and the microwave absorption properties of cobalt particles. The annealed cobalt particles have the maximum reflection loss (RL) of −23.74 dB with a thickness of 1.6 mm, which is a rise of 71.04% compared with the maximum RL of −13.88 dB of the cobalt particles without annealing with a thickness of 2 mm.