Preparation Of High-performance Hexagonal Strontium Ferrite Without Rare-earth

In this paper we have prepared SrFe11.85Co0.15O19by solid-phase sintering method, and studied the changes of the structure and composition of SrFe11.85Co0.15O19phase with different calcining temperature and wet press molding magnetic field. We change the content of CaCO3, Al2O3, SiO2, H3BO3as a secondary milling additives, using calcium gluconate as a secondary milling added dispersant, and then with orthogonal experiment, we choose the most appropriate combination of secondary recipe ingredients and dispersant additives to prepare high-performance M-type strontium ferrite SrFe11.85Co0.15O19. In the second part of the paper, we have prepared the yttrium-doped M-type strontium ferrite Sr1-xYxFe11.85Co0.15O19calcined materials by solid-phase sintering method in1150℃for3h. Then the calcined materials were pressed for magnets under the condition of oriented magnetic field and sintered in1295℃for3h. We have used X-ray diffraction scanning electron microscope and magnetic tester analyze the phase structure of the sintered magnets, the surface morphology of the sintered magnet and the magnetic properties of the sintered magnets respectively.The results showed that with the increase of the sintering temperature, the composition a-Fe2O3phase structure which in the phase of SrFe11.85Co0.15O19diffraction peak present weakened; with the increase of the magnetic field strength H, the magnetic energy of the SrFe11.85Co0.15O19sample increasing; but when H=600kA/m-1magnetic intensity, the magnetic energy of the sample remained unchanged; in the condition of the secondary additive amount CaCO30.8wt%, Al2O30.9wt%, SiO20.5wt%, H3BO30.3wt%, calcium gluconate0.6wt%, the high performance of SrFe11.85Co0.15O19ferrite can be integrated; with the increase of yttrium-doped, the lattice constant a increases first of all and then decreases, c increases slowly, a/c first increases and then decreases, crystal X-ray density dx-ray approximation increases linearly. SEM showed that the magnet has prepared a typical hexagonal structure morphology; Magnetic studies showed that with the doping of yttrium increase, the remanence Br increasing monotonically, intrinsic coercivity Hcj and maximum energy product (BH) max and coercivity magnetic induction Hcb are first increases and then decreases. When the x=1.0, have the maximum remanence Br with 420.7mT, but the intrinsic coercivity Hcj decreases to a minimum value; when x=0.75the intrinsic coercivity Hcj have a maximum value of323.7KA· m-1, and the remanence Br reach410.4mT.