Study On High Frequency Magnetic Properties And Microwave Absorption Of Rare Earth Soft Magnetic Y₂Co₁₇ With Easy-plane Structures

With the rapid development of electronic information technology,a variety of new electronic devices have emerged,and the resulting electromagnetic radiation not only causes serious interference to communication equipment,but also greatly endangers human health.Microwave absorbing material can absorb electromagnetic waves,it is not only used in the field of military stealth,but are also widely used to solve the problems of electromagnetic pollution and interference caused by electronic devices and electronic communications.Therefore,it is necessary to find microwave absorbing materials with excellent performance.Microwave absorbing materials are divided into dielectric materials and magnetic materials.Compared with dielectric materials,magnetic materials are easier to achieve impedance matching,and the matching thickness is thinner,thus becoming a popular absorbing materials.In this paper,Y₂Co₁₇ alloy was prepared by reduction-diffusion method.Firstly,the effect of different diffusion temperatures on the phase composition was investigated,and the crystal structure,microscopic morphology,static magnetic properties of Y₂Co₁₇and the high frequency magnetic properties of its composites were characterized and analyzed.The results show that the maximum initial permeability of the Y₂Co₁₇composite is 6.9 at 50%volume fraction,the real part of the permeability does not change with frequency until 200 MHz,and the magnetization mechanism is dominated by the domain wall displacement.Ball milling of Y₂Co₁₇ to regulate the microscopic morphology of magnetic powder particles,investigate the effect of shape anisotropy on high-frequency magnetic properties,and the optimum conditions for ball milling were determined.The easy-plane rare earth soft magnetic alloy Y₂Co₁₇ has excellent impedance matching characteristics.Therefore,the absorption properties of Y₂Co₁₇ composite were investigated in this paper.The reflection loss of Y₂Co₁₇/PU composite was calculated by measuring their electromagnetic parameters at different ball milling times.By analyzing the absorption properties of Y₂Co₁₇/PU composite with different volume fractions after ball milling,the variation law of reflection loss was obtained;by discussing the microwave absorption mechanism of the composite,the reasons for the appearance of reflection loss absorption peaks were explained,and the perfect matching conditions were given.With volume fraction of 25%composite,when the thickness is1.86 mm,the RL absorption peak frequency is 7.78 GHz,the peak intensity is-65.3d B and the effective absorption bandwidth is 2.73 GHz,it has the perfect matching.When the thickness is 1.5 mm,the effective absorption bandwidth is 3.72 GHz,which basically covers the X-band;when the thickness is 1.08 mm,the effective absorption bandwidth completely covers the Ku-band.Y₂Co₁₇ has a Curie temperature of up to 1167 K.Therefore,its high-temperature microwave absorption properties are investigated in this paper.The effects of Si O₂ and C coating on the high temperature performance of Y₂Co₁₇ composite were discussed.Finally,it is determined that Y₂Co₁₇@C/Na₂Si O₃ composite not only have excellent high temperature stability,but also good high temperature absorption properties.When the volume fraction of Y₂Co₁₇@C/Na₂Si O₃ composite is 25%and the thickness is1.96mm,the composite shows excellent absorbtion properties at 25℃to 500℃.In the temperature range,the reflection loss values of Y₂Co₁₇@C/Na₂Si O₃ composite in X band are all below-8 d B,and the absorption peak frequency does not change with temperature basically,and the effective absorption bandwidths are not less than 3.4 GHz and have little change with temperature.