A Facile Route to Insulate Layers of Nanocrystalline Finemet Cores

In the present research, amorphous Fe73.5Si13.5B9Nb3Cu1 (Finemet) foils, ~25µm in thickness and 5mm in width, were prepared by Planar Flow Casting (PFC) process. Wound cores of amorphous Finemet foils were simultaneously annealed and heat treated at 540°C for 60, 120 and 240 minutes in steam and air flow to form oxide insulating coating layer on both surfaces of the foils. The thickness of the insulating coating layer were studied by FE-SEM technique. The study of magnetic properties in amorphous and nanocrystalline states revealed that nanocrystalline cores have superior soft magnetic properties compared with the amorphous ones.