Study On Properties Of NdFeB Magnetic Tiles By Transition-rare Earth Nanomaterials

Since the 21st century,sintered NdFeB is the permanent magnet material with the largest potential for market development and has been widely used in electronic devices with its outstanding magnetic properties.However,the application of NdFeB is limited due to its coercive force and corrosive effects in the expansion of market demand.In order to improve the properties of sintered NdFeB,the researchers added appropriate amounts of rare earth elements such as Dy,Ce,and Ho to improve it's performance during the preparation of sintered NdFe B magnets.Following the increasing amount of rare earth elements being extracted,for the protecting resources and the environment,how can we save the use amount of precious rare earth,and can improve the magnetic and corrosion resistance of NdFeB magnets?Many researchers concerned about the currently topic.At present,it is the effective ways to improve the performance of sintered NdFeB magnets by adding nano-powders to change the grain boundary phase.In order to improve the magnetic properties and corrosion resistance of sintered?PrNd?_29.9Dy_0.1B₁Co₁Cu_0.15Fe_bal+x%Ho?the mass fraction of Ho nanopowder added was 0,0.2%,0.4%,0.6%,and 0.8%,respectively?,it was prepared by the double alloy method.The morphology,microstructure,composition,particle size,hardness,magnetic properties,and corrosion resistance of the sintered Nd Fe B magnets were analyzed using scanning electron microscope,X-ray diffractometer,particle size distribution analyzer,Vickers hardness tester,FE-2100H permanent magnet characteristic automatic measuring instrument,electrochemical workstation.The results show that the increase of the coercive force of the magnet becomes larger with the increase of Ho element mass fraction,the remanence and the maximum magnetic energy product decrease gradually and the largest decrease from 0.6%to 0.8%.When the addition amount was 0.6%Ho,the comprehensive performance was the best,the coercive force of the magnet reached 13.92kOe,which was increased by 5.8%?compared to magnets without Ho?,the remanence and the maximum magnetic energy product slightly decreased by0.3%and 0.2%,respectively,the ratio of I?006?/I?105?was 1.45,the hardness of the magnet was significantly enhanced at 599.58HV and an increase of 8.2%,the magnet density was increased by 1.6%to reach 7.61g/cm³.It shows that the improvement of magnetic properties is closely related to the change of grain boundary microstructure and magnet density,and the torque of Nd FeB magnets with 0.6%Ho is 9.5 times that of the original ferrite magnets on the motor,the torque is higher than that of magnets without Ho by 5.3%.The corrosion resistance of sintered Nd Fe B magnets was measured by an electrochemical workstation and an accelerated corrosion test.The potentiodynamic polarization curves were measured in 3.5%NaCl and 0.005%H₂SO₄ solutions,respectively.When the addition amount is 0.6%Ho,the self-corrosion current reaches the minimum,0.327?A/cm² in the 3.5%NaCl solution,and 0.452?A/cm² in the 0.005%H₂SO₄ solution,which is improved by nearly one order of magnitude.After 96 hours of hot and humid environment corrosion,the mass loss of the magnets with 0 and 0.6%Ho was 41.3 mg/cm² and 2.6 mg/cm² respectively,the difference between the two was more than ten times,indicating that can increase the magnet resistance corrosion performance by adding Ho nano-powders at the grain boundary.