The production processes of neo magnets are crucial for enhancing the performance. For example, adopting advanced production techniques can minimize the precipitation of the α-Fe phase, thereby improving the magnetic properties and stability of the magnets. Additionally, the inclusion of antioxidants during the preparation process can reduce the oxygen content in the magnets, enhancing the magnetic energy product.
Magnetic Performance Parameters of Neo Magnets
The magnetic performance parameters of neodymium-iron-boron magnets primarily include the following categories:
| Remanence (Br): The magnetic induction retained by the magnet after the external magnetic field is removed, post-technical saturation, reflecting the strength of the magnet.
| Maximum Magnetic Energy Product ((BH)max): The maximum value of the product of B and H on the demagnetization curve, representing the magnet’s capacity to store magnetic energy in a gap. A higher value indicates stronger magnetic performance.
| Magnetic Coercive Force (Hcb): The reverse magnetic field strength required to reduce the internal magnetic induction to zero, reflecting the magnet’s resistance to demagnetization.
| Intrinsic Coercive Force (Hci): The reverse magnetic field strength needed to reduce the magnet’s magnetization to zero, serving as a core indicator of the magnet’s ability to resist demagnetization.
Effects of Production Processes of Neo Magnets on the Magnetism
The production processes of neo magnets significantly influence their magnetic properties. Below are the main production processes of neo magnets and their effects on magnetic performance.
Melting and Powdering Processes
Rapid Quenching Method: By rapidly cooling the alloy melt to form thin cast sheets, a uniform fine crystal structure can be obtained, which is beneficial for improving magnetic properties. However, improper control of roller speed (whether too fast or too slow) can lead to coarse grains or compositional segregation, adversely affecting remanence and coercivity.
Hydrogen Decrepitation (HD) Process
The production processes of neo magnets involve reacting hydrogen with the alloy to shatter the cast sheets into a fine powder, which is then refined to a micron size using airflow milling. Uniformity in powder particle size distribution is crucial; overly coarse or fine sizes can reduce the orientation of magnetic powder, subsequently affecting the residual magnetism and magnetic energy product. A high proportion of single-crystal particles can suppress the formation of antiferromagnetic cores, thereby enhancing the intrinsic coercivity.
Forming Processes
| Injection Molding and Compression Molding: Suitable for complex-shaped magnets, but the molding density significantly affects magnetic performance. Generally, higher density leads to higher magnetic energy product and coercivity. Injection molding requires precise control of temperature, pressure, and injection speed to ensure uniform filling of the magnetic powder, avoiding voids and defects.
| Magnetic Field Orientation During Molding: Applying a magnetic field during the compaction process aligns the easy magnetization directions of the magnetic powder particles along the magnetic field, significantly enhancing remanence and magnetic energy product. The higher the orientation, the better the magnetic performance. Insufficient magnetic field strength or inadequate compaction pressure can lead to reduced orientation and a decline in magnetic properties.
Heat Treatment Processes
| Grain Boundary Diffusion Treatment: By diffusing heavy rare earth elements (such as dysprosium and terbium) at grain boundaries, the high-temperature coercivity of the magnets can be effectively enhanced. However, diffusion time and temperature must be controlled.
Surface Treatment Processes
| Coating Protection: Neodymium magnets are prone to oxidative corrosion. Coatings of metals such as nickel, zinc, or epoxy resin can enhance corrosion resistance and extend the lifespan of the magnets. Improper surface treatment can lead to weak bonding between the coating and the substrate, affecting magnetic performance and surface quality.
Development Directions for the Production Processes of Neo Magnets
The development directions for the production processes of neo magnets focus on several key areas:
Coexistence of High Performance and Low Cost
| Enhancing Magnetic Performance: By employing grain boundary diffusion technology, which is one of the important production processes of neo magnets, the coercivity, remanence, and maximum magnetic energy product can be improved to meet the high-temperature stability and high magnetic energy density demands in high-end applications like electric vehicles and wind power generation.
| Reducing Heavy Rare Earth Usage: Developing low-dysprosium and non-dysprosium formulations to lower costs and mitigate resource pressure.
Process Innovation and Structural Optimization
| Microscopic Structure Control: Optimizing grain boundary phase distribution and the continuity of rare-earth-rich phases, and enhancing mechanical properties and corrosion resistance through nanoparticle doping and gradient structure design.
Greener Production Processes of Neo Magnets
| Resource Recovery and Utilization: Strengthening research and development of rare earth recycling technologies to increase the recovery rates of rare earths from used magnets, alleviating resource shortages.
| Eco-Friendly Processes: Adopting green coating technologies and pollution-free extraction and smelting processes to reduce environmental impact.
Neo Magnets Manufacturer
At Tengye, we’re thrilled to be early participants in your new projects. Our passion for magnets extends from material selection and design optimization to providing magnetic solutions. We hope to bring our knowledge and experience to the forefront by actively engaging in your upcoming projects. Work with our magnet experts to get the right magnet solution.
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