Study Of Composite Bonded Permanent Magnets

Continually improving magnetic properties is one important direction of developing the magnetic materials. However, it is also worthy of investigating how to make use of the merits of the present magnetic materials and make up of weakness through compounding two and more magnetic materials.In this thesis, through the technique's of compressing molding, the processing parameter and the mixture ratio of magnetic powder on magnetic properties of four kinds of binary composite bonded magnets (NdFeB AlNiCo Ferrite SmCo) were studied. The experiment results were analyzed by the method of Polynomial fit. The following major achievements were attained.The optimal processing parameters are as following: the compressing stress is lOOOMPa, powder size 100-120 mesh, the ratio of magnetic powder and adhesive reagent 2.5:100.The Br (BH)max of the binary composite bonded magnets and its single component obey the law of dilution. The interaction between magnetic particles is stronger when SmCo is compounded with other three permanent magnetic materials. Only when content of SmCo is above 50%, the coercive force, Hcj, can remarkably increased. Being a kind of expensive magnetic materials, it is not advisable economically to improve the coercive force through the addition of SmCo.The rules of magnetic properties and the interaction between magnetic particle of binary bonded magnetic materials can be well reflected by the Polynomial fit of Y = A + B1*X + B2*X~2.The reversible temperature coefficient of magnetic flux of NdFeB-Ferrite composite bonded magnets as a function of the content of Ferrite is concave downwards, and that of AINiCo-Ferrite magnets as a function of the content of Ferrite is convex upwards, The reversible temperature coefficient of magnetic flux of the other four binary composite bonded magnets and its single component follow the pattern of linear relationship.