Study On The Insulation Coating Process And Properties Of Pure Iron Soft Magnetic Composite Materials

Electric motor is an important power equipment for "Made in China 2025" and "Industry 4.0",and the power consumption of electric motor accounts for 60% of the total power consumption in China.Magnetic materials are the key to the output power and operating efficiency,and they are usually used in the design of motor stator and rotor.In the stator,the commonly used materials are silicon steel sheet,amorphous alloy strip and other materials with high magnetic permeability and low coercivity.Soft magnetic composites(SMC)have various advantages of their own,such as the ability to maintain consistent magnetic properties in three-dimensional directions,low magnetic losses at high frequencies,and can be designed into various complex structures,thus having a broad application prospect.Therefore,SMC is expected to replace silicon steel sheet in some specific areas of motor applications.In this paper,pure Fe soft magnetic composites with single-layer cladding of silicone resin,polyamide acid,inorganic phosphate,and double-layer cladding of silicone resin/phosphate and polyamide acid/phosphate were prepared from water atomized pure Fe powder.The effects of single-layer silicone resin and polyamide acid cladding on the structure and properties of pure Fe soft magnetic composites were investigated by combining scanning electron microscopy(SEM),X-ray photoelectron spectroscopy analysis,X-ray diffractometer and B-H soft magnetic exchange measurement device.Then the cladding process was optimized to investigate the effects of using silicone resin/phosphate bilayer cladding and polyamide acid/phosphate bilayer cladding on the structure and properties of pure Fe soft magnetic composites.(1)With the increase of silicone resin content,the magnetic permeability of pure Fe soft magnetic composites increases and then decreases,and the loss decreases and then increases.The permeability of pure Fe soft magnetic composites increases and then decreases as the pressing pressure increases,the air gap inside the material decreases,and the magnetic material per unit volume increases.When the pressing pressure increased to 1100 MPa,the highest magnetic permeability was 222.22.For the soft magnetic composites covered with1% polyamide acid,the magnetic permeability tended to increase with the increase of pressing pressure and the increase of magnetic material per unit volume.The highest magnetic permeability was 495.56(1T,1000Hz)when the pressing pressure reached 1500 MPa.(2)Introducing phosphate as the inner cladding layer of the double cladding,with the increase of phosphoric acid mass fraction,the content of non-magnetic material per unit volume increases,and the magnetic permeability and loss show a decreasing trend.With the increase of pressing pressure,the internal air gap of the material decreases,the magnetic material per unit volume increases,and the magnetic permeability and loss show an increasing trend.When the mass fraction of phosphoric acid is 0.6% and the pressing pressure is 1500 MPa,the highest magnetic permeability is 392.6(1T,1000Hz).(3)For the silicone resin/phosphate double cladding,when the mass fraction of phosphoric acid added is 0.6% and the content of silicone resin is 1%,the magnetic permeability tends to increase with the increase of pressing pressure and the increase of magnetic material per unit volume.The highest magnetic permeability was 409.41 at a pressing pressure of 1500 MPa.for the polyamide acid/phosphate cladding,the highest magnetic permeability was 573.93(1 T,1000 Hz)when the mass fraction of phosphoric acid was 0.6%,the content of polyamide acid was 1%,and the pressing pressure was 1500 MPa.The outer organic layer can improve the frequency stability of the magnetic permeability and protect the inner phosphate layer,while the inner phosphate layer can effectively encapsulate to the surface of pure Fe powder,so that the soft magnetic composites have complete insulating properties.Therefore,the double-layer silicone resin/phosphate cladding and polyamido acid/phosphate cladding present better magnetic properties than the single-layer silicone resin cladding and polyamido acid cladding.