Feasibility Of Magnetic Particle Films For Curie Temperature Controlled Processing Of Composite Materials

The feasibility of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composite materials is investigated. If properly designed, these systems should rapidly heat to the particulate material Curie temperature and dwell at that temperature without feedback control. This performance is only possible by maximizing hysteresis heating while eliminating eddy current heating and shielding effects. Models of eddy current heating, hysteresis heating, field penetration thickness, and heat transfer in a particulate film are presented. These models are then used to predict heating behavior of particulate films containing metallic ferromagnetic (nickel), hard magnetic (strontium ferrite), and soft magnetic (nickel zinc ferrite) materials. The results show that soft or semi-hard insulating magnetic materials are best suited for susceptor particles for a broad range of potential military applications. Polymer films with around 10% volume fraction of these materials should be capable of heating rates up to 100 deg C/s in moderate strength 1-10 MHz induction fields.