Research On SmCo₅ And SmCo₅/Fe Dual Phase Nanocomposite Permanent Magnet

Rare earth permanent magnet has been widely used in computer,communication,automobile,aviation,wind power and other industries,and these applications also require higher property.Nd Fe B as contemporary mainstream permanent materials have weak magnetism at higher temperatures.Therefore,it arise an urgent market demand to develope next generation of magnets with excellent magnetic properties.In order to make it,we used SmCo₅with high intrinsic coercivity as the hard magnetic phase andα-Fe with high saturation magnetization as the soft magnetic phase to prepare high-temperature resistant large magnetic energy product magnets at the nanoscale.The research content is as follows:We studied the effect of Co content on the property and phases of SmCo_x（x=4-7）.The magnetic energy product of single phase SmCo_x（x=4-7）is dependent on the remanence.The addition of Co can gradually transfer the phase of raw material from 1:5 phase to 2:17 phase.When the powder was annealed,it was found that the magnetic energy product of 1:5 phase had better performance at the annealing temperature of 500℃while that of 2:17 phase needed 600℃.After hot pressing the powder,the coercive force of SmCo₅with 500℃is 3.6 T,but the magnetic energy product of the hot pressing block is 50-70%than the powder.We adopted the following methods to improve the single-phase performance of SmCo₅.1.We used powder to simulate the heat treatment of hot compression block.2.We replaced Sm element with Pr,and the magnetic energy product was the largest when the substitution amount was 0.5,but the coercivity was greatly reduced.3.Using the raw materials produced by the American company,it is found that under the same conditions,the magnetic energy accumulation is the largest,and the maximum magnetic energy accumulation is 11.2 MGOe when the ball is ground for 2 hours.By using orthogonal test to explore the ball mill SmCo₅&Fe,we got the conditions that the ball material ratio is controlled at 15-30:1,the ball grinding time is 3 h and the soft magnetic phase content is 20-30 wt.%.After that,we studied the effects of different sizes of pellets on the performance and amount of powder under the same conditions,we found that different pellets could provide corresponding energy,while too high or too low energy would have an effect on the later powder,the 9 mm was best.In addition,we hoped to add nonmetal B to increase the biphasic coercivity.The experiment proved that the addition of B can easily preduce the second magnetic properties.The performance of the amorphous powder after ball grinding for 2 h was only 16 MGOe.To improve the performance of the block,we adopted the simulated powder annealing process.Density is a very important factor affecting the magnetic energy product.We prepared high density amorphous blocks with large tonnage of cold pressing and low mass dual-phase amorphous powder for many times,and then obtained a magnet with good performance by annealing at the right temperature repeatedly.Its density was 8.27 g/cm³and its magnetic energy product was 19.1 MGOe.