Method for manufacturing magnetic material
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for manufacturing La(Fe, Si)13-based magnetic materials often require high-temperature homogenizing heat treatment and intermediate phases, which are inefficient and can result in reduced magnetic entropy characteristics due to the presence of α-Fe and other impurities.
Innovation Solution
A method involving a surface oxides decreasing step to remove iron powder surface oxides, followed by mixing with a LaSi compound powder and sintering under vacuum to promote a solid phase reaction, thereby increasing the fraction of the NaZn13-type crystal structure without the need for intermediate phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If arc melting method or high frequency melting method is used to synthesize La(Fe, Si)13-based compound, then the material can be obtained through liquid phase alloying, but a peritectic reaction occurs generating intermediate material with large amount of α-Fe phase and LaFeSi compound phase, and the NaZn13-type crystal structure is not generated almost at all, requiring long-term high-temperature homogenizing heat treatment
Solution Approach 1:
The invention changes the manufacturing parameters by using solid phase reaction instead of liquid phase alloying, and by controlling the atmosphere (vacuum or inert gas) and temperature gradient during sintering. This allows direct formation of NaZn13-type crystal structure without peritectic reaction, eliminating the need for long-term homogenizing heat treatment while maintaining manufacturing efficiency
Solution Approach 2:
The invention utilizes solid phase reaction and phase transition during sintering to directly form the desired NaZn13-type crystal structure from source materials. By controlling the phase transformation process in vacuum or inert atmosphere, the method avoids the harmful peritectic reaction that occurs in liquid phase alloying, achieving both high productivity and short processing time
2Loss of time
If roll-quenching method or forced cooling method is used to solidify molten metal, then the homogenizing heat treatment period can be shortened, but it is still inevitable to pass through the intermediate material stage with α-Fe phase and LaFeSi compound phase
Solution Approach 1:
The invention changes the fundamental manufacturing approach from liquid phase cooling to solid phase reaction under vacuum or inert atmosphere. This parameter change allows direct formation of pure NaZn13-type crystal structure without generating intermediate phases, achieving both short processing time and high crystal structure purity simultaneously
3Ease of manufacture
If boron B or carbon C is added to source material composition to increase generating amount of NaZn13-type crystal structure in intermediate material, then homogenizing heat treatment becomes easier, but approximately greater than or equal to 1.8at% and less than or equal to 5.4at% of B must be added and sub-generated phase such as Fe2B phase may lower properties
Solution Approach 1:
The invention extracts and removes the problematic intermediate material stage and the need for additive elements like boron or carbon. By using solid phase reaction in vacuum or inert atmosphere, the method directly forms the desired NaZn13-type structure without generating intermediate phases that would require chemical additives, thereby maintaining magnetic properties without compromising ease of manufacture
Solution Approach 2:
The invention uses vacuum or inert gas atmosphere during sintering to prevent oxidation and control the reaction environment. This inert environment enables direct solid phase reaction to form pure NaZn13-type crystal structure without needing boron or carbon additives, maintaining both ease of manufacture and magnetic property reliability
4Loss of time
If sintering by applying electric current and heating by pressurizing and applying pulsed electric current at the same time is used, then a sample including relatively large amount of La(Fe, Si)13-based compound can be manufactured within short period without passing through intermediate material, but amount of remaining α-Fe is also large and volume fraction of NaZn13-type crystal structure is lowered
Solution Approach 1:
The invention uses vacuum or inert gas atmosphere during sintering to control the chemical environment and prevent oxidation. This inert environment, combined with optimized sintering parameters, enables complete transformation to NaZn13-type crystal structure without remaining α-Fe phase, achieving both short manufacturing time and high crystal structure fraction
Solution Approach 2:
The invention optimizes sintering parameters including temperature, pressure, and atmosphere composition to achieve complete phase transformation. By carefully controlling these parameters in vacuum or inert atmosphere, the method achieves 100% NaZn13-type crystal structure formation within short time, eliminating the α-Fe phase that remains in conventional spark plasma sintering
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 enhances the volume fraction of the NaZn13-type crystal structure, reduces the Fe content, and improves magnetic entropy characteristics, allowing for more efficient manufacturing of La(Fe, Si)13-based compounds with improved refrigeration properties.
Implementation Method 1
a surface oxides decreasing step of decreasing surface oxides of an iron powder
Implementation Method 2
a sintered body forming step of preparing a sintered body from the powder-molded body obtained by the powder-molded body forming step, by a solid phase reaction under vacuum atmosphere
Implementation Method 3
by a solid phase reaction under vacuum atmosphere
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A method of manufacturing a magnetic material, includes a surface oxides decreasing step of decreasing surface oxides of an iron powder; a powder-molded body forming step of mixing the iron powder whose surface oxides are already decreased obtained by the surface oxides decreasing step, and a compound powder "A" constituted by a La element and a Si element, and compressing and molding the obtained mixture powder; and a sintered body forming step of preparing a sintered body from the powder-molded body obtained by the powder-molded body forming step, by a solid phase reaction under vacuum atmosphere.