Coating technology of Sintered Neodymium Magnets 20161008
Coating technology of Sintered Neodymium Magnets 20161008
NdFeB Permanent Magnets Manufacturer China Rare Earth Magnet Limited
With the excellent performance, the sintered neodymium iron boron magnets are widely used in the electronics, automobile, metallurgical industry, instrumentation, micro motors and other fields. And the demand will be accelerated in the future. However, it is necessary to make surface protection treatment for its poor corrosion resistance. Especially in recent years, the permanent motor magnets always be used under high temperature, high pressure or corrosive environment, the requirements of surface protection is much higher.
There are several ways to protect the magnet surface (Plating & Coating of Sintered Neodymium Permanent Magnets ):
Electroplating
Electroplating is to make the metallic ion deoxidate to metal in the electroplating liquid by external electric current. The electroplating of sintered neodymium magnets is mainly to enhance the resistance of the magnets, and also improve its performance. Besides it can decorate the surface of the magnets. The requirements of electroplating equipment are not too high, and the technology is simple, so it is cheap and easy to mass production. Most of the metal plating on the surface of the coating can be used for neodymium iron boron protection, including Zn, Ni, Cu, CR, Sn, Au, Ag etc. Due to the porous structure and its chemical characteristic, the single-layer coating is often unable to meet higher requirement, therefore, the use of multilayer composite plating can provide more effective protection for surface of the NdFeB magnet generally. So the magnets are always electroplates zinc, Ni-Cu-Ni, Ni-Cu-Ni+Ag, Ni-Cu-Ni+Au, Ni-Cu-Ni+ electrophoresis epoxy coating.
However, for the harsh environments, the surface of electroplate appears some problems such as cracking, peeling, caduceus result to low protection performance. Moreover, the electroplating process usually leads to environment problems.
Chemical plating
Electroless nickel plating technique refers to the metal salts and deoxidizer in redox reaction to make the metallic ion dexidate without the external electric current. Compared with the electroplating, electroless nickel plating is uniform, which is applied to complicated item, the magnet with deep holes, and so on. Meanwhile, with great hardness of electroless nickel plating, the resistance has greatly improved compared with electroplating.
PVD: physical vapor deposition
Japanese manufacturers used a technology between thermal evaporation and thermal spray to make aluminium deposits on the surface of NdFeB permanent magnets for protection, however we haven’t master this technology yet. The stability, density, corrosion resistance are all great of PVD plating. Meanwhile, it is environmental friendly and low cost. There are various of coatings of PVD, but the most common and economical is plating Al.
Parylene coating
Parylene is a new type coating technology, which belongs to chemical vapor deposition, but the sample does not require high temperatures during the deposition process. It is a polymer of p-xylene, which can be divided into N, C, D, HT and many other types.
Parylene coating is uniform, transparent, without stress and additives, which does not damage the artifacts. Besides, it has excellent electrical insulation, protection, and good compatibility with the biological tissue. It is moisture-proof, mildew-proof, corrosion-proof and salt mist proof.
Paint coating
The paint is used to coat and cure in the surface to form a protective film. The way of paint coating are electrophoresis, spray, brush and so on. In addition to protect the surface of neodymium permanent magnets, the paint coating can also used to decorate and mark the NdFeB magnets . The paint coating can be divided into organic and inorganic. The organic coating has higher density and corrosion-proof ability, which will be applied widely. The paint coating can also be used with other coatings.
In a word, among these ways, the permanent magnet manufacturers should choose the most appropriate way in different situation and also improve the coating technology continuously.
NdFeB Permanent Magnets Manufacturer China Rare Earth Magnet Limited
With the excellent performance, the sintered neodymium iron boron magnets are widely used in the electronics, automobile, metallurgical industry, instrumentation, micro motors and other fields. And the demand will be accelerated in the future. However, it is necessary to make surface protection treatment for its poor corrosion resistance. Especially in recent years, the permanent motor magnets always be used under high temperature, high pressure or corrosive environment, the requirements of surface protection is much higher.
There are several ways to protect the magnet surface (Plating & Coating of Sintered Neodymium Permanent Magnets ):
Electroplating
Electroplating is to make the metallic ion deoxidate to metal in the electroplating liquid by external electric current. The electroplating of sintered neodymium magnets is mainly to enhance the resistance of the magnets, and also improve its performance. Besides it can decorate the surface of the magnets. The requirements of electroplating equipment are not too high, and the technology is simple, so it is cheap and easy to mass production. Most of the metal plating on the surface of the coating can be used for neodymium iron boron protection, including Zn, Ni, Cu, CR, Sn, Au, Ag etc. Due to the porous structure and its chemical characteristic, the single-layer coating is often unable to meet higher requirement, therefore, the use of multilayer composite plating can provide more effective protection for surface of the NdFeB magnet generally. So the magnets are always electroplates zinc, Ni-Cu-Ni, Ni-Cu-Ni+Ag, Ni-Cu-Ni+Au, Ni-Cu-Ni+ electrophoresis epoxy coating.
However, for the harsh environments, the surface of electroplate appears some problems such as cracking, peeling, caduceus result to low protection performance. Moreover, the electroplating process usually leads to environment problems.
Chemical plating
Electroless nickel plating technique refers to the metal salts and deoxidizer in redox reaction to make the metallic ion dexidate without the external electric current. Compared with the electroplating, electroless nickel plating is uniform, which is applied to complicated item, the magnet with deep holes, and so on. Meanwhile, with great hardness of electroless nickel plating, the resistance has greatly improved compared with electroplating.
PVD: physical vapor deposition
Japanese manufacturers used a technology between thermal evaporation and thermal spray to make aluminium deposits on the surface of NdFeB permanent magnets for protection, however we haven’t master this technology yet. The stability, density, corrosion resistance are all great of PVD plating. Meanwhile, it is environmental friendly and low cost. There are various of coatings of PVD, but the most common and economical is plating Al.
Parylene coating
Parylene is a new type coating technology, which belongs to chemical vapor deposition, but the sample does not require high temperatures during the deposition process. It is a polymer of p-xylene, which can be divided into N, C, D, HT and many other types.
Parylene coating is uniform, transparent, without stress and additives, which does not damage the artifacts. Besides, it has excellent electrical insulation, protection, and good compatibility with the biological tissue. It is moisture-proof, mildew-proof, corrosion-proof and salt mist proof.
Paint coating
The paint is used to coat and cure in the surface to form a protective film. The way of paint coating are electrophoresis, spray, brush and so on. In addition to protect the surface of neodymium permanent magnets, the paint coating can also used to decorate and mark the NdFeB magnets . The paint coating can be divided into organic and inorganic. The organic coating has higher density and corrosion-proof ability, which will be applied widely. The paint coating can also be used with other coatings.
In a word, among these ways, the permanent magnet manufacturers should choose the most appropriate way in different situation and also improve the coating technology continuously.
