Soft-and-Hard-Magnetic-Materials.ppt

单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Company Logo,*,单击此处编辑母版标题样式,Soft and Hard Magnetic Materials,Classification of Magnetic Materials,Soft Magnetic Materials,Hard Magnetic Materials,Information Magnetic Materials,SpecialFunction Magnetic Materials,By the types of magnetic,Soft Magnetic Materials,Soft magnetic materials are mainly referred to those,easily magnetized repeatedly,and,easily demagnetized,after removal of the external magnetic field.,Definition:,The area within a loop represents a,magnetic energy loss,per unit volume of material per magnetizationdemagnetization cycle.,The relative area within the,hysteresis loop,is small;it is characteristically,thin,and,narrow,.,Fig.18.16 Schematic magnetization curves for Soft magnetic materials,Soft Magnetic Materials,Soft Magnetic Materials,high initial permeability(,i,),high maximum permeability(,max,),low coercivity(,Hc,),high saturation magnetization(,Ms,),low remanence(,Br,),high resistivity,low hysteresis energy loss;,Features:,Soft Magnetic Materials,Composition,Structural Variables,Structural Defects,Influence,factors,saturation magnetization,susceptibility;,coercivity(Hc),domain walls;,coercivity(Hc),hysteresis energy loss,Electrical Resistivity,Soft Magnetic Materials,Classification,metal soft,magnetic materials,ferrite soft,magnetic materials,nano-crystalline,soft magnetic,materials,pure iron;,iron-silicon alloys;,iron-nickel alloys;,permalloy,；,MnZn;NiZn;,MgZn;Co2Y;,Co2Z;,amorphous;,nano-crystalline,；,Soft Magnetic Materials,Soft Magnetic Materials,magnetic amplifier;,pulse transformer,Applications,generators;,motors;,dynamos;,switching circuits,enhance by an appropriate heat treatment,Hard Magnetic Materials,Hard magnetic materials are those have a high resistance to magnetization,and still retain a high residual magnetization after removal of the external magnetic field,also known as,permanent magnet materials.,Definition:,Hard Magnetic Materials,The area within the,hysteresis loop,of hard magnetic materials is,big,;it is characteristically,wide,.,This,energy product,(,BH,),max,corresponds to the area of the largest B-H rectangle that can be constructed within the,second quadrant,of the hysteresis curve.,Fig.18.17 Schematic magnetization curves for Hard magnetic materials,The hysteresis characteristics for soft and hard magnetic materials,are,compared,in Figure 18.18.,From the figure,we can see,the difference,between these two materials in terms of,magnetization,more clearly.,Fig.18.18 Schematic magnetization curves for Soft and Hard magnetic materials,Hard Magnetic Materials,high coercivity(,Hc,),high remanence(,Br,),low initial permeability(,i,),high energy product(,BH,),max,high hysteresis energy loss,high saturation flux density,stability;,Features:,Hard Magnetic Materials,microstructure of material,domain wall motion,external field,Influence,factors,coercivity(Hc);,susceptibility,Hard Magnetic Materials,Classification,metal hard,magnetic materials,ferrite hard,magnetic materials,lanthanon,hard magnetic,materials,magnet steels;,Cu-Ni-Fe alloys,Al-Ni-Co alloys,；,BaO-6Fe2O3;,SrO-6Fe2O3;,SmCo5;,Nd2Fe14B,；,High-energy,Conventional,by the value of,(BH)max,Hard Magnetic Materials,Hard Magnetic Materials,motors;clocks;,cordless drills;screw drivers;automobiles;,audio and video recorders;,Applications,speakers in audio,Systems;lightweight earphones;hearing aids;,computer peripherals;,Thank You!,