The project “Key Technological Development and Application of Fe-based Nanocrystalline Soft Magnetic Materials and Components,” which was led by Professor LU Wei of the School of Materials Science and Engineering, Tongji University, won the first prize of the Shanghai Science and Technology Progress Award 2020. An expert in materials science commented, “Like other core technologies that are urgently needed in China, high-performance soft magnetic materials and components were monopolized by some other countries. The achievement made by Prof. LU Wei’s team has ushered in great opportunities. I’m so excited about it.”
High-performance Fe-based nanocrystalline soft magnetic materials and components
What are high-performance soft magnetic materials? According to LU Wei, they are magnetic materials with high saturation magnetization, high magnetic permeability, low coercivity and low magnetic losses. “We can compare the environment created by a magnetic material to running tracks, and the magnetic permeability to the track lines.” LU explained, “Soft magnetic materials are soft because they have wider and straighter ‘tracks’ that enable their magnetic field lines to pass at a faster rate.” The Fe-based soft magnetic materials developed by LU’s team are low in coercivity and magnetic losses, and thus can be used to make high-quality transformers, inductors, filters and sensors and other components.
LU Wei added, “The ‘tracks’ constructed by our soft magnetic materials show high magnetic permeability, which means that the magnetic field lines can run very fast along the ‘tracks’. The lines, like electric currents, tend to follow the routes with the smallest resistance, so they can run as fast as a bolt of lightning.”
Because of their superior properties, Fe-based nanocrystalline soft magnetic materials and components have long been applied to the production of middle- and high-frequency transformers, electromagnetic devices, current transformers and magnetic sensors that are used in social public security, electricity and electronics sectors. In the context that China has long been importing high-performance soft magnetic materials and components, Prof. LU Wei started the project with support from the National Natural Science Foundation of China and other programs. Beginning with composition design, microstructure regulation, performance regulation and other scientific mechanisms, the team overcame many key technical challenges in R&D and fabrication and finally developed high-performance Fe-based nanocrystalline soft magnetic materials and components that can be mass-produced and used in China.
According to LU Wei, in order to address the weak points of traditional inductor magnetic cores such as inferior and inconsistent performance and low productivity, the team has created the multi-material coupling technology for soft magnetic materials, the protective gas heat treatment technology for Fe-based nanocrystalline magnetic core tunnel furnaces, and the heat treatment technology of utilizing a heat-absorbing unit to suppress the temperature rise of magnetic cores. As a result, a series of Fe-based composite soft magnetic inductors with superior electromagnetic properties were developed and have been put into mass production. In response to public security needs, LU and other team members independently developed Fe-based alloy powder supersonic atomizers and established the doping modification strategy for Fe-based magnetic composite powder for fingerprint visualization, which allows large-scale fabrication of Fe-based magnetic powder for fingerprint visualization. The Fe-based magnetic composite powder developed by the team features high performance, low cost and extensive adaptability and has been applied to visualizing fingerprints in criminal investigations across the country.
“Our priority was to enable the application of the soft magnetic materials in making electronic devices and criminal investigation tools.” LU Wei said, “Our products makes it possible to rapidly recover clear and complete fingerprints anytime and anywhere.” According to his “track” analogy, recovering fingerprints is like visualizing the footprints on the track. To make the visualizations clear and identifiable and the technique easy-to-use, the team made great efforts in improving the mix ratio of materials and synthetic process. Various innovative approaches were employed to apply a coating of nano-scale thickness on the surface of Fe-based soft magnetic powder, enabling the police to easily recover fingerprints.
An expert in criminal investigation said, “The Fe-based nano-scale soft magnetic alloy powder is extraordinary. This high-performance, low-cost product allows easy and rapid recovery of fingerprints anytime and anywhere. As I know, police officers are very happy for it has helped greatly improve crime solving rates. And the people are happy too.”
Visualization of fingerprints
The comment that the judges of the 2020 Shanghai Science and Technology Progress Award have made is as follows: This project has established the doping modification strategy for the Fe-based nanocrystalline soft magnetic materials in the functional confined conditions, revealed the modification mechanism of doping on performance of the Fe-based nanocrystalline soft magnetic materials, and developed multiple composition systems of the Fe-based nanocrystalline soft magnetic materials with high initial permeability and low magnetic losses. It has created a new technology for magnetic field heat treatment of vertical permanent magnets, built the magnetic field heat treatment process with multi-step thermal insulation, solved the technical challenges in fabrication of high-performance Fe-based nanocrystalline soft magnetic materials and magnetic cores, and enabled the development and application of the Fe-based nanocrystalline soft magnetic materials with high initial permeability and low magnetic losses. The research outcomes of the team have been reflected in its 20 invention patents and over 40 published papers.
Team members
https://news.tongji.edu.cn/info/1003/77841.htm
