Preparation method of neodymium iron boron products and neodymium iron boron product prepared by using the same

A preparation method of neodymium iron boron products, comprising the following steps:

• Step S1:
• preparing blank magnet;
• Step S2:
• obtaining preprocessed sheets:
• forming at least one group of welding surface from two opposite sides of the blank magnets, wherein the side of the blank magnet acts as a welding surface, and the distance between two welding surfaces in each group of welding surface is 0.2-12 mm;
• and magnetizing the blank magnet in a direction forming an angle relative to the welding surface to obtain the preprocessed sheets;
• Step S3:
• surface treating:
• cleaning the preprocessed sheets;
• Step S4:
• heavy rare earth coating:
• after surface treating, coating a heavy rare earth containing layer on the welding surface of the preprocessed sheet, wherein the heavy rare earth containing layer is one selected from the group consisting of heavy rare earth metals, heavy rare earth alloys and heavy rare earth compounds;
• Step S5:
• stacking:
• stacking a plurality of preprocessed sheets to give stacked magnets, wherein there is at least one heavy rare earth containing layer between adjacent preprocessed sheets;
• and
• Step S6:
• grain boundary diffusion:
• successively subjecting the stacked magnets to a primary heat treatment for 2-40 min, a secondary heat treatment at 700-1000° C. for 4-40 h, and then tempering at 450-700° C.;
• wherein, in Step S6, the heating mode of stacked magnets is transverse flux heating during the primary heat treatment.