Theoretical and experimental analysis of magnetic inductive heating in ferrite materials

By incorporating magnetic particles into elevated temperature-curing adhesives, or hot-meltable thermoplastics, induction fields can be used to heat bondlines and join composite adherends. In this article we investigate the fundamental heating behaviors of such magnetic particles in order to aid in the design and selection of improved magnetic materials. Magnetic inductive heating tests were performed on two types of magnetic materials: ${\mathrm{Co}}_2{\mathrm{Ba}}_2{\mathrm{Fe}}_{12}{\mathrm{O}}_{22}$ semihard ferrites and ${\mathrm{NiFe}}_2{\mathrm{O}}_4$ soft ferrites. The Curie temperatures of these ferrites were also varied through Zn substitution. All of the samples clearly demonstrated Curie temperature-controlled final heating behavior. The magnitude of heat generation has been related to dc magnetic hysteresis measurements, with reasonable agreement. Deviations are theorized to be due to domain wall resonance effects.