Study On Modification Of Magnetic Metal Powder Absorbent

Absorbent plays an important role in the loss absorbing material, such as carbonyl iron, ferrite and barium titanate, carbonyl iron powder has good absorbing effect, wide absorption band, so it has been widely used.However, carbonyl iron dielectric constant is higher than the permeability constant, such that the impedance matching properties of the material is poor. In order to improve the performance of carbonyl iron,.This paper studies the heat treatment, mechanical ball mill, chemical coating method for modified absorbent.The experimental results show that: by adjusting the ball mill process, heat treatment process and chemical coating of experimental conditions. Heat treatment can improve the magnetic loss of carbonyl iron, maximum absorption peak frequency moves to low frequency; carbonyl iron remanent magnetization and coercive force increases as the heat treatment temperature and time. Mechanical ball grinding can reduce the dielectric constant of carbonyl iron real component values to improve the impedance matching performance. The experimental results show that: in the ball mill speed of 200 r/min, ball grinding time for 10 h, the material ratio of 10:1, bandwidth which is less than-10dB of milled carbonyl iron is 8GHz, the bandwidth increased 1.44 GHz, maximum absorption peak changed from -20.92 dB to -25.36 dB. Chemical coating modification can improve the electromagnetic properties of carbonyl iron and impedance matching performance, in the reaction temperature of 40 ℃, reaction time of 5 h, TEOS addition amount of 20%, pH= 10 modification effect is best, less than-lOdB in the frequency range increases 2.98GHz, maximum absorption peaks changed from 19.8 dB to 22.82 dB.The experimental data shows that: the carbonyl iron by heat treatment, mechanical milling, chemical-coated carbonyl iron can achieve improved performance from the microscopic structure, particle size, surface morphology.Three kinds of experimental methods can improve the electromagnetic properties of carbonyl iron, thus improve their application performance, modification process can be achieved by adjusting the electromagnetic performance improvement purposes.