Effects of PM Processing Parameters and Alloying Elements on the Magnetic Properties of Sintered Iron Powders
Date Issued
2011
Date
2011
Author(s)
Liu, Chia-Wei
Abstract
Iron and iron-base alloys made by Press and Sinter (P/S) process and Metal Injection Molding (MIM) process, are now widely used in a variety of electronic applications. The advantages of P/S and MIM parts include high yield and low cost. However, due to the polymeric binder added to the green parts, impurity level could be too high to achieve good magnetic properties. Four kinds of carbonyl iron powders are used in this study. The magnetic properties are measured after sintering in different heating rates, sintering temperatures and sintering atmospheres. Iron-base soft magnetic alloys are also examined in this study. The alloys are sintered using industrial production parameters to demonstrate its practicability.
The results showed that magnetic properties are greatly influenced by the heating rate during thermal debinding. For the carbonyl iron powder without containing SiO2, when compacted and then sintered at 1350℃ in cracked ammonia for one hour, the coercivity decreased by 13% and permeability increased by 45% after decreasing the heating rate from 5 ℃/min to 3 ℃/min during thermal debinding, and reached
141 A/m and 3880, respectively. Similar behavior is shown in Fe-3 wt% Si alloys, when P/S Fe-3 wt% Si parts are sintered at 1350℃ in cracked ammonia for one hour and at 1350℃ under vacuum for two hours, the maximum induction increased by 15%, the coercivity decreased by 60%, and the permeability increased by 60~70%, when the heating rate is decreased from 3 ℃/min to 2 ℃/min.
The best magnetic properties of P/S iron was obtained using OM powder and using a heating rate of 3 ℃/min for thermal debinding and sintering at 1350℃ in cracked ammonia for one hour. The properties were Bs=1.51 Tesla, Br=1.29 Tesla, Hc=141 A/m, and μmax=3880.
Subjects
Press and Sinter
Metal Injection Molding
Soft Magnetic
Carbonyl Iron Powder
Heating Rate
Type
thesis
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