Method for improving corrosion resistance of neodymium-iron-boron magnetic body

Abstract

The invention discloses a method for improving corrosion resistance of a neodymium-iron-boron magnetic body. The method comprises the following steps: degreasing; performing first ultrasonic water washing; derusting; performing second ultrasonic water washing; performing surface conditioning; performing medium and high temperature phosphating, wherein the pH value of a phosphating solution is 2-4, the concentration of the phosphating solution is 8-20%, the temperature is 60-80 DEG C, and the phosphating time is 10-30min; performing medium and high temperature pure water washing, wherein the temperature of medium and high temperature pure water is 60-90 DEG C, the water washing time is 30-120s, and the electric conduction of the medium and high temperature pure water is not more than 50us / cm; passivating; performing normal temperature pure water washing; drying; soaking in an anti-rust agent, wherein the neodymium-iron-boron magnetic body after drying at normal temperature is soaked in the anti-rust agent with the concentration of 100%, and the soaking time is 10-40min; and carrying out blow drying or drying. The method has the advantages that the anti-rust agent is permeated into a phosphating layer, and a dense corrosion-resistant layer with an anti-oxidation function is formed on the neodymium-iron-boron magnetic body; compared with a traditional way of combining a pretreatment process with a roll-spraying process in the prior art, the corrosion resistance of the product is greatly improved.

Description

technical field [0001] The invention relates to a method for improving anticorrosion performance, in particular to a method for improving anticorrosion performance of NdFeB magnets. Background technique [0002] NdFeB magnets have excellent magnetic properties and high cost performance, and are widely used in technical fields such as electronics, motors and communications. However, the nature of NdFeB magnets is very lively, and the density of NdFeB magnetic powder is much lower than that of steel, the porosity is very high, the pore size is relatively large, and it is easy to be corroded, which will cause problems such as rust, powdering or loss of magnetism. , which greatly limits the service life and application fields of NdFeB magnets. [0003] At present, in order to improve the anti-corrosion performance of NdFeB magnets, the surface is generally coated (including electroplating, electrophoresis and spraying, etc.). However, NdFeB magnets with a single weight of no m...

AI Technical Summary

Problems solved by technology

However, NdFeB magnets with a single weight of no more than 0.1 grams (hereinafter referred to as NdFeB magnets) are too light to be coated. Most of the surface anticorrosion of NdFeB small magnets adopts traditional pretreatment processes and The combination of rolling and spraying process, the specific process is: degreasing (remove the grease on the surface of the magnet) → ultrasonic washing (clean the degreasing liquid on the surface of the magnet) → rust removal (remove the rust on the surface of the magnet) → ultrasonic washing (remove the grease on the surface of the magnet) Descaling solution) → surface adjustment (adjust the metal activity on the surface of the magnet to the maximum) → phosphating at room temperature (forming a phosphating film on the surface of the magnet) → washing with pure water at room temperature (removing the phosphating solution on the surface of the magnet) → passivation (removing the phosphating solution on the surface of the magnet) Phosphate film for sealing) → pure water washing (to remove the passivation solution on the surface of the magnetic steel) → drying → rolling spray

In the above anti-corrosion process, put the small NdFeB magnets and abrasives into the roller spraying machine in proportion to the roller spraying machine and spray the paint while rolling. During the roller spraying process, the collision between the product and the product or the product and the abrasive will destroy the phosphor. The structure of the anti-corrosion coating composed of chemical film and paint, although the anti-corrosion performance of the product has been improved after roller spraying, is still poor. The small NdFeB magnets are tested for neutral salt spray for up to 8 hours