A kind of NdFeB magnetic material phosphating solution

Abstract

The invention relates to the field of neodymium iron boron magnetic material surface treatment, and is mainly applied to neodymium iron boron magnetic material surface corrosion preventing. A neodymium iron boron magnetic material phosphating solution is characterized by comprising 30 g / L-100 g / L of zinc dihydrogen phosphate, 100 g / L-200 g / L of phosphoric acid, 10 g / L-15 g / L of tannic acid, 5 g / L-10 g / L of calcium nitrate, 10 g / L-20 g / L of ammonium molybdate, 50 g / L-70 g / L of phytic acid, 10 g / L-30 g / L of an auxiliary film forming agent and the balance water. The phosphating solution is used for treating a neodymium iron boron material, due to the fact that the phosphating solution is poor in acidity, a magnet is not corroded, the irreversibility, magnetic flux (Br), coercivity (Hcj) and other magnetic properties of the magnet are kept unchangeable before and after phosphorization, and the phosphating solution is especially suitable for small magnets with the thickness smaller than 5 mm and the unit weight smaller than 5 g. The phytic acid is added in the phosphating solution, the film forming speed is high, a phosphating film is smaller than 2 microns in thickness and is far thinner than a traditional phosphating film, but the corrosion resistance is still better than that of a traditional phosphating solution, the high-temperature and damp-hot resisting time of the phosphating film is four hours, the surface of the magnet is free of red rust, and the phosphating film can serve as a final protection film.

Description

technical field [0001] The invention relates to the technical field of magnets, in particular to a phosphating solution for NdFeB magnetic materials, which is mainly used for surface anticorrosion of NdFeB magnetic materials. Background technique [0002] As the third-generation rare earth permanent magnet material, NdFeB magnets have extremely high magnetic energy product and coercive force, and the advantages of high energy density make them not only widely used in information technology, automobiles, nuclear magnetic resonance and motors, but also in wind power The application of environmentally friendly new energy fields such as power generation and hybrid vehicles is also increasing. The high magnetic energy of NdFeB stems from its special chemical composition and crystal phase structure: NdFeB magnets are made of Nd 2 Fe 14 The B main phase and the intergranular Nd-rich phase are composed. The electrochemical potential difference between the phases of this multi-phas...

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Problems solved by technology

[0004] Patent 201210481482.8 proposes a method to improve the corrosion resistance of the phosphating film on the surface of NdFeB permanent magnets, but the phosphating time is long, the phosphating process is complicated, the energy consumption is large, and the production efficiency is low

[0005] Patent 201510412944.4 proposes a phosphating solution as a protective layer for the final treatment of magnetic materials, but the formula of this phosphating solution is complicated, and the temperature of the phosphating solution is relatively high, so the influence on the magnetic properties of the magnet is not analyzed

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