Development of a “top-down” production route for Nd-Fe-B magnets

The aim of the Pioneer Fund project is the validation of this process for further implementation in industrial production. The manufacturing process for permanent magnets offers varied advantages compared with the conventional sintering process, such as a lower number of manufacturing steps, higher efficiency as well as lower energy consumption and so on. If the achieved magnetic properties are comparable to those of commercial sintered magnets, the state-of-the-art sintering process for permanent magnets can be replaced in some areas by the continuous top-down approach.

Motivation

Permanent magnetic materials play an increasingly important role for technologies in the fields of energy generation, mobility, as well as in automation and entertainment industry. The production of permanent magnets has taken a strong upturn in the last decade, and the demand for magnets has increased dramatically due to the increasing automation, as well as the change from combustion engines to electromobility.

Figure 1: Comparison of manufacturing routes with its process steps and microstructures. Top: conventional powder metallurgical process; blow: new top-down route through forming process

Due to their high magnetic energy density, the neodymium-iron-boron (Nd-Fe-B) alloys are among the most important permanent magnet materials. However, this alloy is permanent-magnetic only if it has a specific microstructure (e.g. as small as possible grain-size and magnetic texture). The conventional Nd-Fe-B magnets production nowadays takes place via a powder metallurgical route through sintering, which is a complex manufacturing process and associated with high costs in the value added.

In the project “New top-down synthesis methods” of the LOEWE RESPONSE project at the TU Darmstadt, a forming process route was developed and patented by the departments PtU, PhM and FM starting from Nd-Fe-B castings. The goal of this process route is a cheap and efficient production of Nd-Fe-B permanent magnets compared to the classical powder route by means of a continuous forming process. The previous results have demonstrated the high potential of this process route by achieving significant magnetic hardening (increase in remanence and coercivity).

Figure 2: Project Kick-Off 2018. Persons from left to right: M.Sc. Corinna Müller (project team), Dipl.-Ing. Thorsten Gröb (project team), Prof. Dr. Oliver Gutfleisch (head of project), Dr. Stefan Riegg (project coordination), M.Sc. Fansun Chi, (project coordination), Prof. Dr.-Ing Dipl.-Wirtsch.-Ing. Peter Groche (head of project), Robert Heitzmann (Innovation Manager of TU Darmstadt, Pioneer Fund), Dr.-Ing. Enrico Bruder (project coordination)

Acknowledgment

The proposed research project is funded by by TU Darmstadt and ENTEGA NATURpur Institut GmbH.