Research on Iron Powder Purity and Processing Conditions for Soft Magnetic Composites

High purity and high compressibility iron powder is commonly used in soft magnetic composite(SMC)materials for producing high performance motor cores.If it can be substituted by some less pure iron powders,the cost for SMC production would be decreased greatly.In order to characterize the effects of iron powder purity on the extents of compaction and work hardening,three iron powders of different purities are utilized to analyze the changes in green density and surface microhardness under different processing conditions.Resultsindicate that many characteristics of iron powder,such as purity,type and content of impurities and iron particle morphology influence the green density of compacts.After annealing in nitrogen at 500℃ with the holding time of 30min,the hardness of the less pure powders decrease by about 30%,while that of high purity powder under the same condition is unconspicuous.When heating up to the recrystallization temperature,the recrystallization process of iron grains results in the reduction of the microhardness by less than 50%.