Preparation And Properties Of Iron Nitride Soft Magnetic Composites

Soft magnetic composite material is a kind of composite material obtained by uniformly mixing metal magnetic powders and insulating coating medium and molding by molding.Due to its excellent soft magnetic properties,soft magnetic composite materials are widely used in electrical and electrical engineering,artificial intelligence,5G communication,medical and health and other fields.The insulating coating medium of traditional soft magnetic composite materials generally uses high resistivity ceramic materials,and such materials are usually non-magnetic.The introduction of non-magnetic insulating substances will reduce the saturation magnetization and permeability of soft magnetic composite materials,so choose A suitable insulating material is very important.In this paper,Fe₃N/Fe,Fe₃N/Fe₄N and Fe-N solid solution soft magnetic composites were prepared by gas-phase nitridation method.The insulating material is iron nitrogen compound,and its saturation magnetization is similar to that of iron powder,with high resistivity and high magnetic permeability,which is expected to improve the soft magnetic properties of SMCs.The research contents and main conclusions are as follows:（1）Preparation of Fe₃N/Fe soft magnetic composites by gas phase nitridation and research on soft magnetic properties.Fe₃N/Fe was obtained from spherical iron powder at 500℃in pure NH₃ atmosphere,and then mixed with an appropriate amount of PVP.The study found that:with the increasing of nitriding time,the content of Fe₃N phase increased,and pure Fe₃N phase was prepared by being nitride for 5 hours;with the prolongation of nitriding time,the surface of the product gradually became rough.Small cracks appeared in the sample.With increasing of nitriding time,the saturation magnetization of the sample gradually decreased,and the saturation magnetization after nitriding for 5 hours was the lowest,which was82.9 emu/g.The rate and magnetic loss are reduced,and the magnetic loss is the lowest for the samples nitrided for 5 hours.The quality factor Q and loss tangent of the nitrided samples are improved,and the magnetic properties of the nitrided samples are even better.The microwave absorption performance of the sample nitrided for 5 hours is the best,reaching a maximum value of-24.69 d B at 7.36 GHz,and the effective absorption bandwidth is 2.3 GHz,indicating that the sample has better microwave absorption characteristics,stronger absorption capacity and wider absorption frequency range.The samples nitrided for 5 hours have high magnetic permeability real partμ′under high frequency conditions,and have good magnetic storage capacity and strong frequency stability.The real part of the dielectric constant is relatively stable,and the capacitor has better stability at high frequencies.The imaginary part of the permittivityε′′is low,indicating that the conductivity is low and the resistance is high under high frequency conditions.（2）Preparation and soft magnetic properties of Fe₃N/Fe₄N soft magnetic composites prepared by gas-phase nitridation.The spherical iron powder was nitrided for 8 hours at 500℃in an atmosphere of NH₃:H₂=1:1 to obtain pure Fe₄N,and the Fe₄N obtained by nitridation was obtained at 500℃in a pure NH₃ atmosphere to obtain Fe₃N/Fe₄N,and then mixed with an appropriate amount of PVP uniformly,After mechanical pressing and annealing at 650℃,Fe₃N/Fe₄N soft magnetic composites were obtained.The conclusions are as follows:with the increase of nitriding time,the Fe₃N content increases,the nitridation reaches saturation at 5 hours of nitridation time,and the phase composition does not change with the increase of nitriding time;the saturation magnetization of the sample increases with the increase of nitridation time.After nitriding,the permeability and magnetic loss of the sample after nitriding decreased,the sample loss was dominated by the hysteresis loss,and the eddy current loss was larger.reduce.With the increase of nitridation time,the complex magnetic permeability of the samples increased,and the samples nitrided for 8 hours had the highest quality factor,the lowest loss tangent value and excellent magnetic properties.（3）Preparation and soft magnetic properties of Fe-N soft magnetic composites prepared by gas-phase nitridation.The spherical iron powder is mixed evenly with an appropriate amount of PVP,and then annealed at 650℃after mechanical pressing to obtain an iron-based magnetic powder core.The iron ring samples were obtained at 250℃under pure NH₃ atmosphere.The conclusions are as follows:the samples with nitridation time of 12 hours and24 hours have higher magnetic permeability than the original samples,and the magnetic loss of nitridation for 12 hours is the lowest.With the increase of frequency,the sample loss is dominated by hysteresis loss and gradually transformed into eddy current loss;with the increase of nitriding time,the real part of the complex permeability decreases,and the decrease of the complex permeability of the sample after nitriding for 1 hour is the smallest,high frequency stability,the highest quality factor,the lowest loss tangent value,and the best comprehensive magnetic performance.In this paper,the insulation medium of soft magnetic composite is studied deeply,and the coating layer of iron nitride with excellent performance is obtained by nitriding the soft magnetic material of iron powder matrix by gas phase nitriding method,which effectively reduces the magnetic loss of soft magnetic composite and improves the comprehensive magnetic properties of the material.