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The editor tells you what are the passivation methods for NdFeB magnets

by:Maghard      2021-03-01
The author tells you what are the passivation treatment methods for neodymium iron boron magnets. Release time: 2021-02-18 Views: 547 The author tells you what are the passivation treatment methods for neodymium iron boron magnets, which are easy to be oxidized and corroded. Strict anti-corrosion treatment must be carried out before use, which should be the main purpose of NdFeB surface treatment. In addition, the surface treatment of neodymium iron boron has the following purposes: (1) Remove loose magnetic particles on the surface of the magnet through surface treatment, avoid affecting the magnetic function or damaging the magnetic system, and achieve the purpose of smooth surface; (2) Surface protective coating can prevent Magnetic particles fall off due to mechanical stress during magnet assembly or operation (especially the edges). Today, I will talk about the passivation treatment of NdFeB magnets and hope that it will help and understand everyone. NdFeB passivation is similar to phosphating, which forms a protective film on the surface of the workpiece through chemical methods to achieve the purpose of anti-corrosion. Surface chemical conversion coating technology is a commonly used surface treatment method. At present, NdFeB surface chemical conversion film treatment mainly adopts phosphating technology, mostly ordinary zinc or iron phosphating. The phosphating film itself has poor corrosion resistance and often does not independently undertake the anti-corrosion effect, but cooperates with electrophoresis and coating as the outer composite anti-corrosion ; At the same time, phosphoric acid and phosphate compounds are widely used in the phosphating process, which is prone to phosphorus pollution, causing adverse consequences such as eutrophication of water bodies, and the production process is not environmentally friendly. Compared with the phosphating agent, the passivating agent has simple ingredients, does not contain phosphoric acid and phosphate compounds, and is more environmentally friendly. The NdFeB passivation process is generally as follows: degreasing water washing, ultrasonic water washing, pickling water washing, ultrasonic water washing, pure water washing, passivation treatment, pure water washing, pure water washing, dehydration and drying. Degreasing: Degreasing can only remove grease, dust, sweat and attached metal debris on the surface of NdFeB, but cannot remove rust on the magnet. The oil stains on the surface of NdFeB come from the processing of materials, such as anti-rust grease used for rust prevention during storage and transportation, and cutting fluid contacted by parts during cutting. The oil on the surface of NdFeB must be cleaned before further surface treatment, otherwise it will affect the quality of surface chemical conversion, electroplating or coating. Due to the wide range of sources and types of oil pollution, the degree of pollution varies greatly, so the problem of oil removal is very complicated. In order to avoid corrosion and subsequent residues in the degreasing process, degreasing agents with low free alkalinity and total alkalinity should be used as much as possible. Suitable for pickling: The purpose of pickling is to remove the black ash and rust remaining on the surface of NdFeB. The pickling solution generally uses 2% to 4% nitric acid for 0.5 to 2.0 min. High acid concentration and long pickling time are not good for magnets. Passivation: The passivation treatment method is to put the magnet in a container containing passivation liquid, soak or spray for a period of time, or to electrify the magnet as an anode for polarization, which can achieve passivation, that is, a passivation film is formed on its surface . As an important surface anticorrosion treatment method, passivation is widely used in many metals, especially aluminum, zinc, cadmium, tin, magnesium and their alloy materials. Traditional passivation treatment mostly uses chromic acid and chromate as treatment agents, which is called chromate passivation. The chromate conversion film formed on the metal surface after treatment has a good anti-corrosion protection effect on the base metal. As a separate protective film, passivation treatment is simple, practical and low-cost, and has been widely used in the early development of NdFeB. But its fatal weakness is that it contains toxic Cr(), which is harmful to the human body and the environment, prompting people to actively carry out research on effective alternative technologies. In recent years, there have been many patents for passivation agents in my country, including oxalic acid, surfactants, and complexing agents. They are simple in composition and have degreasing, rust removal and passivation functions. It is a more convenient and environmentally friendly passivation for NdFeB magnets. It does not use phosphoric acid and phosphate compounds. In recent years, the requirements for the corrosion resistance of NdFeB conversion coatings have become higher and higher, and it is difficult to meet the requirements by passivation technology alone. The commonly used technology is to use composite conversion coating technology, that is, phosphating first and then passivation. By filling the pores of the phosphate coating, the corrosion resistance of the composite conversion coating can be effectively improved. The above is what the author shared for you about the passivation method of NdFeB. I hope it will help and understand you. The Dongguan Magnetoelectric production base is located in Dongguan, one of the four major cities in Beijing, Shanghai, Guangzhou and Shenzhen. The company is mainly engaged in Ru0026D, production and sales of neodymium iron boron, samarium cobalt magnets and their components. It has international advanced production equipment, testing equipment and modern plants. The facilities and products are at the domestic and international level. It is one of the largest enterprises in the permanent magnet industry. Our company promises favorable price and reliable quality, welcome to consult. Custom magnets need to know Previous post: What are the characteristics of NdFeB?
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