Preparation method of nickel phosphorus alloy plating on surface of sintered neodymium iron boron permanent magnet

Abstract

The invention relates to the field of chemical treatment of metal material surfaces, in particular to a preparation method of a corrosion-resistant chemical nickel-plated phosphorus alloy plating. Reagents such as polyvinylidene fluoride, fluorine carbon type cationic surface active agents, 2-acrylamido-2-methyl-1-propane sulfonic acid and the like are adopted as raw materials; and through a solution-alkalization / thermal-induction chemical stem grafting technology, 2-acrylamido-2-methyl-1-propane sulfonic acid polymers are evenly grafted into the chemical nickel-plated phosphorus alloy plating, so as to enable the surface of the plating to be loaded with sulfonic acid groups with cation selective permeability. By adopting the preparation method, the migration and the permeating of chloride ions towards the inner part of the plating can be effectively restrained and retarded, the occurrence of pitting corrosion, slot corrosion and intergranular corrosion caused by the aggressive chloride ions is reduced, the protection performance of the nickel phosphorus alloy plating over a sintered neodymium iron boron permanent magnet is improved, and the application of the sintered neodymium iron boron permanent magnet to each industrial field is expanded.

Description

technical field

[0001] The invention relates to the field of chemical surface treatment of metal materials, in particular to a method for preparing a corrosion-resistant electroless nickel-phosphorus alloy coating. Background technique

[0002] Sintered NdFeB permanent magnets are known as the "Magnetic King". Boron permanent magnets can be widely used in motors, magnetic resonance imaging, computers, magnetic separation and other fields. However, the Curie temperature and working temperature of NdFeB permanent magnets are low, and they are easily oxidized and corroded in environmental media, which leads to a sharp decline in their magnetic properties, thus limiting their applications.

[0003] Intergranular corrosion is the main corrosion method of NdFeB permanent magnets in hot and humid environment. The "phase selective" corrosion process is a typical corrosion process of magnets. The Nd-rich phase in the magnet alloy first corrodes, and then the main phase Nd 2 Fe 14 ...

Examples

Embodiment Construction

[0043] The specific implementation method of the present invention will be further described in detail below.

[0044] This embodiment uses the chemical modification process described in the present invention to improve the corrosion resistance of the nickel-phosphorus alloy coating on the surface of the sintered NdFeB permanent magnet. The process of chemically modifying the nickel-phosphorus electroless alloy coating on the surface of the magnet, the specific steps are as follows:

[0045] (1) Pretreatment of the surface of sintered NdFeB permanent magnet:

[0046] First, use 40#, 80#, 300# sandpaper to polish the surface of the sintered NdFeB permanent magnet, and then use 600#, 800# and 1000# water sandpaper to finely grind the surface of the magnet, and use deionized water Clean to make the surface clean, flat and smooth;

[0047] Carry out surface sealing treatment on the polished magnet, first boil it in deionized water for 5 minutes, and then place the magnet in an u...

technical field

[0001] The invention relates to the field of chemical surface treatment of metal materials, in particular to a method for preparing a corrosion-resistant electroless nickel-phosphorus alloy coating. Background technique

[0002] Sintered NdFeB permanent magnets are known as the "Magnetic King". Boron permanent magnets can be widely used in motors, magnetic resonance imaging, computers, magnetic separation and other fields. However, the Curie temperature and working temperature of NdFeB permanent magnets are low, and they are easily oxidized and corroded in environmental media, which leads to a sharp decline in their magnetic properties, thus limiting their applications.

[0003] Intergranular corrosion is the main corrosion method of NdFeB permanent magnets in hot and humid environment. The "phase selective" corrosion process is a typical corrosion process of magnets. The Nd-rich phase in the magnet alloy first corrodes, and then the main phase Nd 2 Fe 14 ...

Examples

Embodiment Construction

[0043] The specific implementation method of the present invention will be further described in detail below.

[0044] This embodiment uses the chemical modification process described in the present invention to improve the corrosion resistance of the nickel-phosphorus alloy coating on the surface of the sintered NdFeB permanent magnet. The process of chemically modifying the nickel-phosphorus electroless alloy coating on the surface of the magnet, the specific steps are as follows:

[0045] (1) Pretreatment of the surface of sintered NdFeB permanent magnet:

[0046] First, use 40#, 80#, 300# sandpaper to polish the surface of the sintered NdFeB permanent magnet, and then use 600#, 800# and 1000# water sandpaper to finely grind the surface of the magnet, and use deionized water Clean to make the surface clean, flat and smooth;

[0047] Carry out surface sealing treatment on the polished magnet, first boil it in deionized water for 5 minutes, and then place the magnet in an u...