Preparation Of Iron Family Amorphous And Electromagnetic Microwave Absorbing Properties

With the rapid development of electronic technology,the electromagnetic interference has become very serious with the high integration of electronic devices between the components of devices.With increases in use of electromagnetic microwave in various fields,electromagnetic pollution has become the fourth pollution following the air pollution,water pollution and noise pollution.Electromagnetic pollution as a novel kind of pollution to the environment,it is harmful to communication,national defense and human health.So,it is significant to prepare the excellent absorbing material.In order to improve the ability of weapons and equipment to survive and penetration capability,absorbing technology can be applied to the military field to realize stealth technology.It can also be used in the field of civilian industry,such as electromagnetic interference,information security and human body protection application.Magnetic metal powders have attracted wide attention in the field of microwave absorption due to their high Curie temperature,high saturation magnetization,and high permeability.However,the disadvantage of magnetic metal powders is that the higher dielectric constant does not make it easy to achieve impedance matching.Because of the same excellent magnetic properties,the absorbing properties of iron family amorphous powders were studied.It is possible to achieve the good impedance matching by high resistivity properties of the amorphous powders.The main contents and conclusions are as follows:(1)The amorphous ribbon with the nominal composition of C064.08Fe4.104B22.4Si5.6Nb3.si6 was prepared by the single copper roller melt-spinning method.The ribbons were milled under the atmosphere of high purity argon by using a planet ball mill.First,the effect of mass fraction of powders on the microwave absorbing properties was investigated.As shown of results,with the increase of mass fraction of absorber,the value of reflection loss(RL)decreased first,and then increased.It may be because of the poor impedance matching character for high mass fraction.when the mass fraction of powders is 70%,the amorphous powders has the maximum value of RL=-13.8 dB.(2)By the chemical corrosion process to modify the surface of Co-based amorphous powders to improve the microwave absorbing properties.The effect of pH and corrosion time of chemical corrosion process on the microwave absorbing properties was investigated.The results shows that with the decrease in pH,the value of RL decreased initially and then increased.The value of RL decreased initially and then increased with the increase of corrosion time.In the condition of initial pH of 2 and corrosion time of 1 hour the amorphous powders have the maximum value of RL=-45.2dB.(3)By the mechanical milled of graphene and Co-based amorphous powders to prepare the composite materials.The effect of mass fraction of graphene for composite materials on the microwave absorbing properties was investigated.As shown in experiments,when the corroded powders were compounded with graphene of 8%,the maximum RL value increased in the situation of thin coat thickness.The maximum value of RL=-39.3 dB with a thickness of only 1.4 mm.(4)By the same method,the economical Fe-based amorphous powders with the nominal composition of Fe76Si7.6B9.5P5Ci1.9 was prepared.The effect of mass fraction and chemical corrosion process on the microwave absorbing properties was investigated.As shown in experiments,when the mass fraction of powders is 70%,the maximum value of RL =-34.2 dB.When the condition of initial pH of 3 and corrosion time of 10 min the the maximum value of RL=-68.9 dB.(5)The effect of mass fraction of ternary Fe-based amorphous powder with the nominal composition of Fe6sCo20B15 on the microwave absorbing properties was investigated.As shown in experiments,when the mass fraction is 60%,the maximum value of RL =-50.3 dB.