Rare Earth Bonded Magnetic Powder With La/Ce Diffusion for Heat Resistance
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Solution Overview
Problem
The heat resistance of anisotropic neodymium-iron-boron magnetic powder, used in bonded magnets, is insufficient, leading to potential irreversible demagnetization at high temperatures, and existing methods to improve coercivity are costly and complex, particularly when using heavy rare earth elements.
Innovation Solution
A method involving the preparation of a raw powder with RTBH as the main component, followed by the addition of La/Ce hydride and copper powder, and subsequent diffusion heat treatment to enhance the grain boundary phase, increasing coercivity without relying on expensive heavy rare earth elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If medium and heavy rare earth elements (Tb, Dy) are directly added to increase coercivity, then heat resistance is improved, but production cost increases substantially and remanence decreases
Solution Approach 1:
The patent changes the chemical composition parameters by using light rare earth elements (La, Ce) instead of heavy rare earth elements (Tb, Dy), and controls the content of R2T14B phase and grain boundary phase to optimize coercivity without heavy rare earth addition
Solution Approach 2:
The patent creates a composite microstructure consisting of R2T14B main phase and grain boundary phase with specific composition ratios, where the grain boundary phase contains rare earth elements that improve coercivity without requiring heavy rare earth additions to the bulk material
2Reliability
If grain boundary diffusion process is used to improve coercivity, then heat resistance is improved, but production process complexity increases
Solution Approach 1:
The patent simplifies the process by directly controlling the composition parameters of the starting alloy (adding La, Ce, Cu elements in specific amounts) and heat treatment parameters (temperature 800-900°C, time 5-24h), eliminating the need for complex grain boundary diffusion process control
3Reliability
If heavy rare earth elements are added to increase coercivity, then heat resistance is improved, but magnetic energy product decreases due to antiferromagnetic coupling
Solution Approach 1:
The patent changes the rare earth element composition from heavy rare earth (Tb, Dy) to light rare earth (La, Ce) elements, and optimizes the content of R2T14B phase (70-80 wt%) and grain boundary phase (20-30 wt%) to achieve high coercivity without antiferromagnetic coupling losses
Solution Approach 2:
The patent designs a composite microstructure with R2T14B main phase and grain boundary phase, where the grain boundary phase contains light rare earth elements that improve coercivity without causing the antiferromagnetic coupling effect that reduces magnetic energy product
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
This approach effectively increases the coercivity of the magnetic powder, enhancing heat resistance while reducing production costs by utilizing abundant and inexpensive La and Ce elements, thus improving the magnetic performance without significant remanence reduction.
Implementation Method 1
subjecting the mixture to diffusion heat treatment
Implementation Method 2
subjecting the mixture to diffusion heat treatment
Data Source
AI summary
A method for preparing a rare earth anisotropic bonded magnetic powder, comprises the following steps: (1) preparing raw powder with RTBH as the main component, wherein, R is Nd or Pr/Nd, and T is a transition metal containing Fe; (2) adding La hydride or Ce hydride and copper powder to the raw powder to form a mixture; (3) subjecting the mixture to atmosphere diffusion heat treatment to give the rare earth anisotropic bonded magnetic powder.