The invention relates to a
manganese zinc ferrite material for an
eddy current type approach switch, a film-coated
magnetic core and a preparing method of the
manganese zinc ferrite material. The principal component of the
manganese zinc ferrite material contains: 51.5-53 mol% of Fe2O3, 24.0-25.0 mol% of Mn3O4 and 20.50-22.5 mol% of ZnO; and the accessory component of the
manganese zinc ferrite material contains:0.50-1.00 wt% of nanometer TiO2, 0.30-0.50 wt% of nanometer SiO2, 1.00-1.50 wt% of nanometer CaO, 0.05-0.35 wt% of nanometer Co2O3 and 0.05-0.10 wt% of nanometer SnO2. The
manganese zinc ferrite material is made in the
oxide method, formed in mold pressing mode, sintered and grinded and then subjected to
film coating on the outer surface of the
magnetic core, a
transition layer is made of chrome, and a target layer is made of
palladium. Resistivity of the
manganese zinc ferrite material in 1 MHz is that rho>=10 ohmm, relative temperature
thermal index of the manganese
zinc ferrite material in the temperature range of -55 DEG C to 25 DEG C is that alpha muir<=(0.3-1.2)*10-6 / DEG C, and relative temperature
thermal index of the manganese
zinc ferrite material in the temperature range of 25 DEG C to 100 DEG C is that alpha muir<=(0.4-1.6)*10-6 / DEG C. The
magnetic core with the film-coated outer surface has excellent
electromagnetic shielding performance, and meets requirements of the
eddy current type approach switch for the ferrite material of being high in resistivity, small in specific
temperature coefficient and strong in anti-jamming capability.