Phosphate-Coated SmFeN Magnetic Powder With pH-Controlled Deposition
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Solution Overview
Problem
Existing methods for producing phosphate-coated SmFeN-based anisotropic magnetic powders do not consistently achieve high coercivity due to inadequate phosphate deposition and coating thickness, particularly when using organic solvents and improper pH adjustments.
Innovation Solution
A method involving a phosphate treatment step where an inorganic acid is added to a slurry containing SmFeN-based anisotropic magnetic powder, water, and a phosphate compound to adjust the pH to 1-4.5, promoting increased phosphate deposition and a dense, thick coating, followed by an optional oxidation treatment to enhance coercivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a phosphate treatment solution with improper pH adjustment is used, then the coating process is simple, but the phosphate deposition is insufficient and coating thickness is inadequate
Solution Approach 1:
The patent applies parameter changes by optimizing the pH value of the phosphate treatment solution to a specific range (1-4.5) to maximize phosphate deposition on the SmFeN-based anisotropic magnetic powder surface. This parameter optimization directly addresses the contradiction by achieving adequate coating thickness through controlled chemical conditions rather than complex multi-step processes
Solution Approach 2:
The patent employs preliminary action by performing pH adjustment of the phosphate treatment solution before the coating process. This preliminary preparation ensures that the solution is optimally conditioned for phosphate deposition, thereby achieving sufficient coating thickness in a single straightforward treatment step without requiring complex in-process adjustments
2Reliability
If organic solvents are used in the phosphate treatment, then the coating process is simplified, but phosphate deposition is insufficient and coercivity is not improved
Solution Approach 1:
The patent applies parameter changes by switching from organic solvents to water as the solvent medium and optimizing the pH range to 1-4.5. This parameter change enables sufficient phosphate deposition that improves coercivity while maintaining ease of manufacture, as water-based solutions are simpler to handle and dispose of compared to organic solvents
3Reliability
If the surface is coated with phosphate but without proper pH control, then the coating process is straightforward, but coercivity improvement is not achieved
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pH value within the range of 1-4.5 during phosphate treatment. This parameter control ensures adequate phosphate deposition on the magnetic powder surface, which directly improves coercivity while keeping the manufacturing process straightforward and easy to implement
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 method produces phosphate-coated SmFeN-based anisotropic magnetic powders with improved coercivity and an exothermic onset temperature of 170°C or higher, ensuring high magnetic properties and resistance to oxidation.
Implementation Method 1
adding an inorganic acid to a slurry containing an SmFeN-based anisotropic magnetic powder, water, and a phosphate compound to adjust a pH of the slurry to a range from 1 to 4.5 to form an SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate
Implementation Method 2
adjust a pH of the slurry to a range from 1 to 4.5 to form an SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate
Implementation Method 3
Japanese Patent Publication No. 2014-160794 indicates that the coercivity of an SmFeN-based anisotropic magnetic powder coated with a phosphate is increased by subjecting the phosphate-coated SmFeN-based anisotropic magnetic powder to an oxidation treatment
Data Source
AI summary
A method for producing a phosphate-coated SmFeN-based anisotropic magnetic powder, the method includes a phosphate treatment of adding an inorganic acid to a slurry containing an SmFeN-based anisotropic magnetic powder, water, and a phosphate compound to adjust a pH of the slurry to a range of 1 to 4.5 to form a phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate.