Single-Phase SmFe12 Magnetic Powder With Micron-Scale Particle Control
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Solution Overview
Problem
Existing methods for preparing SmFe12-based magnets face challenges in achieving single-phase magnetic powder with controlled particle size, as phase separation occurs when hydrogen is absorbed, making it difficult to maintain single-phase particles.
Innovation Solution
A method involving a mixture of rare earth oxide, metal, metal oxide, and reducing agent is used, with heat-treating at 800 °C to 1100 °C to produce Sm0.8Zr0.2(Fe0.8Co0.2)11Ti1 or Sm(Fe0.8Co0.2)11 magnetic powder, which results in a single-phase powder with an average particle size of 10 micrometers or less, using a reduction-diffusion process without additional pulverizing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strip casting or melt spinning method is used to prepare SmFe12-based magnet, then metal powder can be obtained, but it is difficult to obtain single-phase powder with controlled particle size of several micrometers
Solution Approach 1:
The invention changes the preparation parameters by using a reduction-diffusion process at controlled temperatures (900-1100°C) with specific rare earth oxide compositions and reducing agents, achieving both single-phase composition and controlled particle size of 3-10 micrometers, unlike conventional strip casting or melt spinning methods
Solution Approach 2:
The invention introduces a reducing agent as an intermediary substance that facilitates the reduction-diffusion process, enabling the formation of single-phase SmFe12-based magnetic powder with controlled particle size by mediating the chemical reaction between rare earth oxide and metal powders
2Length of moving object
If jet mill is used to make particles small, then particle size is reduced, but phase separation occurs when hydrogen is absorbed, making it difficult to maintain single-phase
Solution Approach 1:
The invention performs preliminary action by controlling the particle size to 3-10 micrometers through the reduction-diffusion process before hydrogen absorption can occur, and by establishing a single-phase composition that is resistant to phase separation during subsequent hydrogen exposure
Solution Approach 2:
The invention changes the chemical composition parameters by using specific rare earth oxide compositions and controlling the reduction-diffusion process, creating a stable single-phase structure that maintains its composition even when hydrogen is absorbed during particle size reduction
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 allows for the production of single-phase magnetic powder with reduced secondary phase content and controlled particle size, maintaining high saturation magnetization and coercive force of the main phase.
Implementation Method 1
a rare earth-transition metal based master alloy in which the amount of a rare earth element(s) present in the master alloy is a surplus by a specified amount or above than the stoichiometric composition of a rare earth element(s) present in the main phase thereof is produced from a raw material mixture comprising a surplus rare earth oxide powder, transition metal powder and a reducing agent by utilizing a reduction diffusion process
Implementation Method 2
is produced from a raw material mixture comprising a surplus rare earth oxide powder, transition metal powder and a reducing agent by utilizing a reduction diffusion process
Implementation Method 3
synthesizing magnetic powder by heat-treating the mixture at a temperature of 800 °C to 1100 °C with a reduction-diffusion method
Data Source
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AI summary
The magnetic powder according to an embodiment of the present disclosure are powder particles synthesized using a mixture of a rare earth oxide, a raw material, a metal, a metal oxide and a reducing agent, wherein the powder particles are single-phase, the raw material includes at least one of Fe and Co, the metal includes at least one of Ti, Zr, Mn, Mo, V and Si, and the metal oxide includes at least one of MnO2, MoO3, V2O5, SiO2, ZrO2 and TiO2.