Large Block, High Density, Low Weight Loss Rate and Excellent Plating Process for High Grade NdFeB Magnet

In order to produce N44SH and N40UH high-grade magnet, both strip casting and hydrogen decrepitation processes were adopted, and the subsequent milling, sintering and heat-treatment processes were improved. The density of N40UH magnet is risen up to 7.65 g/cmc. Weight loss rate after the Highly Accelerated Stress Test (HAST) for 48 hours is less than 0.2 mg/cmb. The microstructure of magnet shows that the grain size is between 5 to 8 μm. The rich-Nd phase is fine and uniform, the pinhole is very few, such magnet can be used for wind power generator after phosphoruster treatment directly, and it can also be used in hydrogen atmosphere of hybrid car after surface treatment.