Joint research and development by universities and enterprises have led to a breakthrough in the anti-oxidation technology for NdFeB magnets.

Recently, the "gradient nano-coating" anti-oxidation technology jointly developed by the School of Materials Science and Engineering at Harbin Institute of Technology and Ningbo Yunsheng Co., Ltd. has passed industrial verification. This technology employs a composite process of magnetron sputtering and atomic layer deposition to construct a 50-nanometer-thick rare earth-aluminum-titanium multilayer protective film on the surface of NdFeB magnets, extending their anti-oxidation lifespan in high-temperature and high-humidity environments to 8,000 hours, a threefold increase compared to traditional processes.

Traditional NdFeB magnets rely on electroplated nickel layers for protection and are prone to intergranular corrosion at temperatures above 150℃. Through synchrotron radiation characterization, the new technology reveals that the oxidation-blocking layer formed by La elements in the gradient coating can reduce the oxygen diffusion coefficient to 1.2×10⁻¹⁸ cm²/s. Coupled with the "pinning effect" of Al₂O₃ nanocrystalline boundaries, it reduces the corrosion rate of the magnets by 92% in salt spray tests.

The research team has developed an "online defect detection + laser repair" system, which has increased the coating yield rate to 99.2%. After third-party testing, the magnets exhibited a mere 2.3% decay rate in magnetic energy product after being placed for 1,000 hours under conditions of 85℃/85% humidity, far surpassing the industry standard of 8%. Currently, this technology has been applied to magnets in wind turbines, extending the maintenance cycle of the units from 18 months to 5 years.

"This solves the application bottleneck of high-end magnets in hot and humid environments," noted an expert from the China Rare Earth Industry Association. Assuming an annual production capacity of 100,000 tons, the new technology can reduce magnet scrap by 12,000 tons and save 2,300 tons of rare earth resources. Relevant achievements have been granted 12 national invention patents, and the first production line with an annual capacity of 3,000 tons will be put into operation next year, expected to provide key material support for electric motors in new energy vehicles and offshore wind power equipment.