R-T-B Permanent Magnet Composition for High Remanence and Coercivity
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Solution Overview
Problem
Existing R-T-B-based sintered magnets face a challenge in maintaining magnetic coercivity while increasing magnetic remanence, as higher sintering temperatures often lead to abnormal grain growth and reduced coercivity.
Innovation Solution
Incorporating high-melting-point metals like Ti, Zr, and Nb, along with specific ratios of R, B, M, Fe, and Co, forms a RaMbXcTd phase to enhance sintering density and maintain coercivity while improving remanence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sintering temperature is increased to improve sintered density and magnetic remanence, then magnetic remanence is improved, but abnormal grain growth occurs leading to decreased magnetic coercivity
Solution Approach 1:
The patent optimizes the composition parameters by controlling the content of high-melting-point metals (Ti, Zr, Nb) within specific ranges (0.01-5 wt%, preferably 0.1-3 wt%) and adjusting the R/T/B ratio. This parameter optimization allows achieving high sintered density and remanence while preventing abnormal grain growth that would reduce coercivity
Solution Approach 2:
The patent creates a composite microstructure consisting of the main R2T14B phase combined with intermetallic phases (RaMbXcTd where T is Fe/Co and X is Cu/Al/Ga). This composite structure enables the material to achieve both high remanence (≥13.09 kGs) and high coercivity (≥25.2 kOe) simultaneously by combining the advantages of different phases
2Quantity of substance
If sintering time is prolonged to increase sintered density, then magnetic remanence is improved, but production efficiency decreases and grain growth occurs reducing coercivity
Solution Approach 1:
The patent modifies the sintering process parameters by optimizing the temperature-time profile. The specific composition enables achieving high density with reduced sintering time (1-4 hours at 950-1100°C) compared to conventional processes, thereby improving production efficiency while maintaining or enhancing both remanence and coercivity
3Reliability
If boride phase is formed to prevent grain growth and improve coercivity, then magnetic coercivity is improved, but volume ratio of main phase is reduced leading to decreased remanence
Solution Approach 1:
The patent inverts the conventional approach by avoiding boride formation altogether. Instead of using boride-forming elements (Ti, Zr, Nb) to precipitate borides at grain boundaries, the patent controls the composition and sintering process to prevent boride formation, thereby maintaining high main phase volume ratio and achieving high remanence while still improving coercivity through alternative mechanisms (intermetallic phase formation and grain boundary effects)
Solution Approach 2:
The patent forms a composite structure with intermetallic phases (RaMbXcTd) that provide grain boundary strengthening and coercivity enhancement without the harmful effects of boride phases. This composite approach allows simultaneous achievement of high coercivity and high remanence
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The R-T-B-based permanent magnet material achieves high remanence (Br ≥ 13.09 kGs) and coercivity (Hcj ≥ 25.2 kOe) simultaneously, with improved sintering properties and squareness.
Implementation Method 1
sintering temperature is increased or sintering time is prolonged in order to increase sintered density
Data Source
AI summary
Disclosed are an R-T-B-based permanent magnet material, a preparation method therefor and the use thereof. The R-T-B-based permanent magnet material comprises R, B, M, Fe, Co, X and inevitable impurities, wherein: (1) R is a rare earth element, and the R includes at least Nd and RH, M being one or more of Ti, Zr and Nb, and X including Cu, “Al and/or Ga”; and (2) in percentage by weight, R: 30.5-32.0 wt %, B: 0.95-0.99 wt %, M: 0.3-0.6 wt %, X: 0.8-1.8 wt %, and Cu: 0.35-0.50 wt %, and the balance is Fe, Co and inevitable impurities. According to the present invention, under the condition of 0.3-0.6 wt % of a high melting point metal, a permanent magnet material with an excellent magnet performance and a good squareness is obtained.