Sintered Lamellar Soft Magnetic Composites: Shaping and Magnetic Properties

Sintered lamellar soft magnetic composite (SL-SMC) is a promising material for power frequency applications and for all types of electric motors, including induction motors. Alumina coated Fe-3%Si particles cut from steel sheets offer both the advantages of standard laminated steel products, and of soft magnetic composites (SMC). As SMC's, this material can be shaped using standard near-net shape powder metallurgy (P/M) techniques, which represents a big advantage over coated laminated steel assemblies. Indeed, the P/M process, as compared to laminated steel assemblies, gives access to better design and improved motor assembling techniques, at lower production costs, by limiting machining and stamping. The unique structure of the SL-SMC offers better DC magnetic properties than standard SMC's, allowing them to cover a larger range of applications. However, there still remains work to be done in developing this new technology to its full potential, using low cost industrial techniques. This paper is divided into two main parts. The first is dedicated towards assessing the possibility of producing SL-SMC parts using an automatic industrial compaction press. The impact of two different lubrication systems, admixed solid lubricants and die wall lubrication, on the density and green strength of the motor parts, will be determined. Also, the process capability will be evaluated on the basis of "part to part" stability. The second section of this study will determine the impact of different processing parameters on the mechanical and magnetic properties of the Fe-3%Si alloy. Results show that by carefully controlling heat treatment, very high maximum induction, low magnetic loss and good mechanical property, can all be reached in fabricated parts.