The Microwave Absorbing Properties Of Nickel-zinc Ferrite And Iron Matrix Composites

Magnetic metal powders and ferrite materials,which was commonly used as absorbers,possessed many advantages,but there are still significant drawbacks that can not achieve the desired absorbing properties in many cases.In order to get better absorbing properties,the two materials are compounded together.The main contents of this paper are as follows:?1?The Ni-Zn ferrite with different composition was prepared by using Fe₂O₃,NiO,ZnO and CuO powders.The effects of different components on the microwave absorbing properties were studied.With the change of the composition,the maximum particle size of the composition is basically the same,and its absorption peak and its position are changed,and the best absorbing performance is-55 d B?920MHz?when ZnO = 27mol%.?2?The effects of calcination temperature and milling time on the microwave absorbing properties were studied by changing the preparation process.The results show that the calcination temperature has little effect on the particle size,and the best absorbing performance is-38.7d B?925MHz?at 1170 ?.The milling time has a great influence on the particle size.With the increase of the milling time,the particle size decreases correspondingly,the maximum absorption peak becomes larger and moves to high frequency,and has the largest absorption peak-35.7 d B?940 MHz?at the ball milling time of 14 h.?3?The flaky carbonyl iron was prepared by mechanical ball milling,and the nickel-zinc ferrite/flaky carbonyl iron powder composite was prepared by direct mixing method.It was found that with the increase of nickel-zinc ferrite content,the absorption bandwidth became larger and then smaller,and its absorption peak reached-17.5d B when the flaky carbonyl iron: nickel-zinc ferrite = 4: 6,And has a maximum absorption bandwidth of less than-10 d B.?4?Fe₃O₄/flaky carbonyl iron powder core-shell composite was prepared by hydrothermal method.The effects of pH value,reaction temperature and holding timeon properties were studied.When the reaction temperature is 170 ? and the holding time is 0.5h,with the change of pH value,the optimum absorbing performance is18 d B?4.8GHz?at pH = 14.When the pH = 7 and the holding time is 0.5h,the optimum temperature is 160?,and have a largest value of 16.5d B?3.5GHz?.When the reaction temperature is 170?,and the pH = 7,with the change of holding time,it got a largest value of-17 d B?4.3GHz?at the holding time is 2h.What is more,for all the prepared the absorbing material with core-shell structure,have a good thermal stability,which can be applied to more complex environment.