Research On Fast Measurement Methods For Thermal Stability Of NdFeB Permanent Magnet Materials

As an important sub project supported by the National Key Technologies R&D Program, this dissertation is devoted to the research on the fast measurement methods for thermal stability of sintered NdFeB materials in order to study some fast measurement methods and devices for thermal stability of sintered NdFeB materials for electrical machines.Four parts are included as follows:First of all, basing on IEC standards and Chinese national standards about sintered NdFeB materials, in the paper the high-temperature, room-temperature properties and thermal stability of about two hundred samples of NdFeB materials for electrical machines produced by twenty representative manufactories in China are measured and analyzed. Combining with the analysis results, properties conclusions of sintered NdFeB materials produced in China are concluded.Secondly, basing on the analysis and research to the original measurement system NIM-10000H, the methods of exerting demagnetizing electric current and measuring flux are found out and the device is designed. Experiments are made to prove the feasibility of the device. Although there is feasibility in theory, it should be further research and perfection on making sure the exact electrical current.In the third part, it is researched that no exerting electrical current but changing materials' working point to realize fast measurement. Permanent magnetic materials can be measured fast by the method which has been analyzed in theory. But this method is going on research because it is limited by the thickness of materials.The method that calculating thermal stability by the known room-temperature properties of materials is brought forward in the forth part of the dissertation. The method is basis on the curves measured in the first part. Combining with the calculative formulas, experiments are made on samples of NdFeB materials to prove the feasibility of this method. By using thismethod, it can be concluded whether the samples is regular as long as the room-temperature properties of materials is known.