Study On The Iron Substitution And Technology Of High Performance M-type Strontium-ferrite

M-type permanent magnet ferrites were found in the fifty years of the 19th century. Due to its low cost, simple production process and stable chemical properties, it has been widely used in a variety of devices, such as speaker, motor, household appliances, etc. With the developments of science and technology, the development of electronic devices tends to be miniaturization and lightweight, at the same time of M-type of permanent magnetic ferrite can have higher requirements. In order to obtain high performance of M-type permanent magnet ferrite, many researchers have adopted the ion substitution and improve process to improve M-type of permanent magnetic ferrite magnets. Since the La-Co substituted M-type permanent ferrite was found, because of its high magnetic properties has been produced and used in the industry widely.In this paper, we have prepared the La-Co substituted strontium permanent magnetic ferrite Sr1-xLaxFe12-yCorO19 by the traditional ceramics, the effect of different x/y was studied in Sr1-xLaxFe12-yCoyO19 ferrite magnets. The results show that the magnet with the composition of Sr0.80La0.20Fe11.65Co0.15O19 has good magnetic performance. On this basis, we have synthesized M-type strontium ferrite permanent magnet Sr0.80-nCanLa0.20Fe11.85Co0.15O19 (n= 0-0.15) by the substituting calcium for strontium, respectively sintered under 1175 ℃,1185 ℃ and 1195 ℃. The phase of the powders was checked by using the X-ray powder diffraction (XRD), the morphology of the magnets was observed by a HITACHI S-4800 electronic scanning electron microscope (SEM). The NIM-2000HF permanent magnet magnetic measuring instrument was utilized to measured the magnetic properties of permanent magnets.The conclusions are as follows:1. when x=0.20, y=0.15, Sr1-xLaxFe12-yCoyO19 permanent magnet has a higher magnetic properties.2. when z=11.65, Sr0.08La0.20FezCo0.15O19 (11.25≤z≤12.05) can achieves a higher magnetic performance.3, when n≤0.12. the ceramics prepared Sr0.80-nCanLa0.02Fe11.65Co0.15O19 permanent magnetic ferrite (n=0-0.15) with a single M phase. 4, Another phase of hematite (α-Fe2O3) starts to occur in Sr0.80-nCanLa0.20Fe11.65Co0.15O19 (n=0-0.15) permanent magnetic ferrite as n=0.15.5, As the increase in the amount of Ca2+ doping, the lattice constant a of the Sr0.80-nCanLa0.20Fe11.65Co0.15O19 (n=0-0.15) ferrite gradually increases and the lattice constant c decreases. 6, Observed by SEM graphics, with the increase of Ca2+ doping amount, the grain size of Sr0.80-nCanLa0.20Fe11.65Co0.15O19 (n=0-0.15) ferrite increases gradually. 7, In the compositional range from n=0 to n=0.15, the remanence Br, intrinsic coercive force Hcj, maximum magnetic energy product (BH)max of Sr0.80-nCanLa0.20Fe11.65Co0.15O19 (n=0-0.15) ferrites increase at first, then decrease gradually, and the Br and (BH)max achieve the maximum value with n = 0.08, Hcj obtains the maxinmrn value with n=0.12.8, Sr0.80-nCanLa0.20Fe11.65Co0.15O19(n=0-0.15) ferrite were sintered under 1175, 1185 and 1195 ℃, the results show that the ferrite which sintered under 1185 ℃ has a favor magnetic performance, and obtained the best magnetic properties when n=0.08.