Microstructural and magnetic analyses of the sinterization effects in rare earth permanent magnets (NdFeB) using grain boundary diffusion under 900 °C and 1000 °C.

• Grant number: 23/06403-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2023
• End date: May 31, 2024
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Mateus Botani de Souza Dias
• Grantee: Luisa Lopes de Azevedo
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

During COP-26, Brazil committed to reducing carbon emissions by up to 50% by 2030. One alternative to achieve this goal is the use of wind farms to produce electricity and the substitution of internal combustion engine vehicles with hybrid or electric vehicles. In both cases, rare earth supermagnets (NdFeB) must be used to allow for more efficient wind turbines and electric motors. However, China's monopoly on the commercialization of rare earth magnets exposes Brazil to commercial fluctuations that can directly affect the production chain of these devices. Therefore, the project aims to explore the technical feasibility of recycling magnets for reuse in wind turbines and electric motors. To do this, the hysteresis cycles of commercial samples that have been recycled and subjected to the grain boundary diffusion (GBD) process will be compared, which is expected to restore the magnetic properties of recycled magnets. For this purpose, the samples subjected to the GBD process will be examined at two different temperatures (900 °C and 1000 °C) and two different times (1 hour and 10 hours), aiming to find the condition that has the highest coercive field, remanent field, and maximum energy product. In addition, microstructural, chemical, and domain structure analyses will be performed to explain the variations in magnetic properties. Finally, it is expected that the results of this project will allow us to verify the technical feasibility of using the GBD process to recover the magnetic properties of recycled rare earth magnets.