Tunable electromagnetic properties and enhanced microwave absorption ability of flaky graphite/cobalt zinc ferrite composites

• Flaky graphite/cobalt zinc ferrite composites were synthesized.
• The microwave absorption mechanism was discussed.
• Tunable electromagnetic properties and enhanced microwave absorption properties.
• It is significant to design ferrite/carbon composites as microwave absorber.

In this study, the flaky graphite/cobalt zinc ferrite composites were synthesized by the coprecipitation method. The XRD results showed that the flaky graphite/cobalt zinc ferrite composites can be obtained and there is no impurity when the graphite weight ratio is less than 20 wt%. The FE-SEM results exhibited that the flaky graphite/cobalt zinc ferrite composites possessed flake-like shape with high aspect ratio. Moreover, the electromagnetic properties could be tuned by varying the graphite weight ratio. In the series of as-prepared flaky graphite/cobalt zinc ferrite composites, the sample with 10 wt% graphite possessed excellent impedance matching performance. As a result, the it exhibited the best microwave absorption properties. The reflection loss was less than −10 dB in frequency range of 10.3–13.5 GHz and the maximum reflection loss was reach to −33.85 dB at 11.7 GHz when the coating thickness was 2.5 mm. Moreover, the electromagnetic analysis demonstrated that the electromagnetic loss properties and the electromagnetic impedance matching performance should be both satisfied to obtain the excellent microwave absorption properties. This study was meaningful to design the ferrite/carbon composites based microwave absorbers.

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