What is the NdFeB Infiltration Technology?
If you are looking for a way to increase the resistance to corrosion of your metal, you might be interested in a process known as NdFeB infiltration technology. This process is a way to do this by doing things like doping the surface of the metal, which will allow it to have a higher coercivity. In addition to the doping, there is also a posttreatment process that can be used to improve the corrosion resistance of the metal with Alnico magnets.
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Electroplating protection technology
Electroplating protection technology is a promising solution for the problem of corrosion resistance of NdFeB permanent magnet. PVD plating has good stability and bonding force. Its ability to produce a wide range of coatings makes it a viable option for neodymium magnet surface protection.
The protective layer is a composite layer. It is composed of different materials such as metals and resin 3D prints. Among the common protective coatings for NdFeB are nickel, zinc, copper and tin plating.
However, these coatings have a relatively poor corrosion resistance. This is because of the pore structure of NdFeB. Hence, it is necessary to apply an effective post-treatment process to improve corrosion resistance.
One method of protecting NdFeB is to use an alloy electroplating technique. In fact, a combination of alloy and electroplating technologies can greatly improve the corrosion resistance of NdFeB.
When the anode and cathode are placed in a chemical bath, electricity is generated to cause the transfer of positively charged ions to the anode. These ions are then transferred to the workpiece surface. As a result, the surface of the workpiece is encapsulated by a thin shell of metal.
An alkaline or acidic aqueous electrolyte solution will remain in the pore of the NdFeB matrix. Therefore, it is necessary to avoid the presence of water, alkali and other substances.
After the protective layer is applied, the NdFeB permanent magnet is operated under certain temperature conditions. At these temperatures, it reacts with water vapor to form a hydrogen precipitate. The precipitate causes bubbling and hydrogen embrittlement.
Thus, the present invention aims to provide a composite protection technology for NdFeB permanent magnets. It can improve the performance of NdFeB and meet the service requirements in harsh environment.
There are various pretreatment processes for electroless plating. The main treatment is abrasive grinding, hole sealing, chamfering and picking oxide film.
Anodic electrolytic etching can increase the binding force of the protective coating. It can also improve the corrosion resistance of the coating. Finally, it can eliminate the oxide film and improve the performance of the coating.
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Laser powder bed fusion
Laser powder bed fusion infiltration technology is an additive manufacturing (AM) technique that employs a high-energy laser beam. This technology can produce lattice structures, and it can also form metallic components. Its application has been growing in the commercial practice of Sintered NdFeB magnets.
The basic idea is to sinter a metal powder. However, it has been used for a wide variety of materials. For example, it can be applied to aluminum alloys, titanium alloys, and stainless steel. In addition, it can process polymers in gaseous atmospheres.
The process is divided into two main phases. First, the powder material is spread on the build platform. After that, a heat source is used to fuse the powder particles. Finally, the excess powder is removed. These techniques can be used to produce functional ceramic parts, without the need for post-sintering steps.
A key component of this technology is the high-temperature preheating system. This system is designed to minimize thermal tensions in the first layers of the building process. Using this technique, the energy density required for full melting can be lowered.
In the present study, we studied the impact of different processing conditions on the microhardness of Ti-48Al-2Cr-2Nb powder. We found that a Tpreheat of 800 degC enabled a microhardness of 350 HV.
We measured the temperature variations in the powder bed using a K-type thermocouple. Additionally, we extracted multifractal features from layer-by-layer images. X-ray computed tomography images were then used to determine the effects of the process parameters.
Although the study is preliminary, the results show that the temperature of the baseplate can be controlled. This is done by controlling the thickness of the powder layers. Further, we discovered that the cooling rate is 5 degC min-1.
The resulting parts are more dense than other AM processes. This makes the process suitable for production of parts with cast microstructure. Besides, it can be used to fabricate a wide variety of exotic metals. Moreover, it can also be used to build aircraft components.
However, some limitations are encountered in the processing of alloys. For instance, g-TiAl alloys can be difficult to weld due to their high cracking sensitivity.
Coercivity enhancement by doping
Increasing the coercivity of NdFeB magnets is a very important issue. A lot of effort has been invested in this area. In addition to traditional approaches such as adding a heavy rare earth (HRE) to the starting material, more effective techniques are also being explored. Some of these include alloy infiltration, reduction in the amount of intergranular phases and increased density.
Various types of alloy powders can be used to enhance the coercivity of NdFeB nanocomposites. These alloy powders can be prepared from Tb, La, Dy, and Ce, and each powder can be doped into commercial NdFeB powders. The use of these alloy powders has been shown to increase the coercivity of hot deformed NdFeB magnets. This is because of the doping effect of the alloy powders.
Aside from the element distribution, the enhancement of coercivity is also believed to be due to the introduction of a magnetic crystalline anisotropy. This anisotropy is said to increase the length of the effective exchange coupling. Moreover, pinning of domain walls at defect positions is also believed to contribute to the improvement of the magnetic properties.
To study the influence of the thickness of the surface defects on the angle of coercivity, single-grain computed results were carried out. These results were found to be in good agreement with the experimental data. They showed that the thickness of the defect plays a significant role in the process of reversal. Consequently, remanence is expected to decrease. Therefore, it is important to keep a high texture to maintain a comparable energy product.
Enhanced coercivity can be also achieved by applying a low eutectic Nd-Cu diffusion. This process was used to produce nanocrystalline NdFeB magnets. It was also shown that the coercivity of these magnets is enhanced to 2.6 T. Although this technique is still relatively new, it has been successfully utilized to manufacture high coercivity magnets.
An effective way of enhancing the coercivity of HD NdFeB magnets is to add R80Al20 alloy powders. This alloy contains Tb, La, Dy, and Ce, which can significantly enhance the coercivity of HD NdFeB magnetic materials for Neodymium magnets.
Posttreatment process to improve corrosion resistance
Developing a corrosion resistant posttreatment process for NdFeB permanent magnetic material is an important part of improving the service life of such materials. These new energy vehicles require high coercive force and consistency. There are several important aspects to consider when developing such a posttreatment process, including the pre-plating and plating processes, and the post-plating process.
Pre-plating and electroplating are two main types of plating processes. The first involves chemical conversion, and the second includes hole sealing and activation. In general, a good preplating process will improve the corrosion resistance of a material.
An effective posttreatment process can also help improve the corrosion resistance of a coating. A coating can become brittle because of residues of the electrolyte solution, or oxidation can ruin the surface layer. When dealing with NdFeB materials, physical vapor deposition (PVD) is a promising technique for corrosion protection. It is environmentally friendly and produces small grains, uniform thickness, and excellent film adhesion.
After a PVD protective coating is applied to a NdFeB, the workpiece must be dry. If the coating is not dried, a higher speed of corrosion can be observed. Moreover, the bonding force between the film and the substrate is low. This can cause problems with the integrity of the coating.
Several studies investigated the effects of various preparation treatments on the morphology of the coating. Surface roughness can also increase the binding force between the film and the matrix. Therefore, it is necessary to develop a multi-technology composite preparation method.
Besides, the pretreatment process for preparing NdFeB material is an important factor for Axial Flux Permanent Magnet Generator. In addition, the alloy elements that are added to the NdFeB magnet are often doped. Doping elements can cause exsolution within the grain boundary of the primary Nd-rich phase. But doping element insertion can also affect temperature stability.
Post-plating treatments for NdFeB materials are also an important aspect. Usually, common post-plating treatments include shot peening and vacuum heat treatment. However, the study of relevant PVD pretreatment technology is still limited.
Compared with the traditional sandpaper grinding and polishing treatment, the organic infiltration rapid solidification agent is a suitable pore-sealing agent. Sandpaper grinding and polishing treatment cannot be used for bulk NdFeB materials.
