Study On Densification Technology Of Soft Magnetic Materials For Claw-pole Prepared By Powder Metallurgy

There are many shortcomings,such as low purity,composition segregation,heavy oxidation,complicated process and much subsequent machining,in preparation of the claw-pole materials by the traditional methods(for example the investment casting and the press working),which brings bad influences on the magnetic properties of the workpiece.In this research,the material preparation processes based on the powder metallurgy technology were investigated,including the powder selection,the mixing ratio,the forming,the forging,the sintering and the subsequent heat treatment,in order to improve the density of the soft magnetic material,and further its magnetic properties.The materials were prepared by several procedures,pressing at room temperature,pressing at certain temperature,powder forging,and sintering in different conditions.The specimens were tested by XRD,SEM,VSM and so on,to obtain their microstructions and properties.Finally,the density of the material was close to the theoretical value with the optimized parameters.Results show that the atomized iron powder has better formability than the reduced iron powder.Using a powder mixed by 100 and 300 mesh number as the raw material,the specimen density can be as high as 7.46g/cm~3.The magnetic properties ofM_s andH_c are205.51emu/g and 7.89Oe,respectively.By optimized powder forging procedure,the density of the atomized iron powder forging can be improved to 7.821g/cm~3.After sintered at 1450?for 2h,and with a slow cooling down method,the specimen propertyM_s can be 209.32emu/g,H_c can be 5.49Oe,58.46%lower than that without heat treatment,which reaches the claw pole forging level in domestic.