Permanent Ferrite Arc Magnet Compressive Strength via Slurry Control
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Solution Overview
Problem
Current methods for improving the compressive strength of permanent ferrite arc magnets are not systematic and often result in reduced magnetic performance or inconsistent particle size distributions, making it difficult to meet the increasing demands for miniaturization and energy efficiency.
Innovation Solution
A novel two-stage vertical cell milling process is used to achieve a uniform particle size distribution in the slurry, combined with the addition of a self-made liquid dispersant to improve fluidity and density consistency during magnetic field molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of permanent ferrite arc magnets is reduced to meet miniaturization requirements, then the volume and energy efficiency are improved, but the compressive strength decreases
Solution Approach 1:
The patent changes the particle size distribution parameters of the slurry from conventional ranges to a specific optimized range (D0.10: 0.4-0.6 μm, D0.50: 0.8-1.0 μm, D0.90: 1.9-2.0 μm). This parameter optimization enables thinner magnet designs to maintain sufficient compressive strength by ensuring uniform particle packing and reducing structural defects at reduced thicknesses.
Solution Approach 2:
The patent segments the particle size distribution into three distinct size ranges (fine, medium, and coarse particles) with specific D-values. This segmentation allows different particle sizes to fill interstices between each other, creating a denser, more uniform microstructure that enhances compressive strength even in thin-section arc magnets.
2Ease of manufacture
If conventional ball milling methods are used to control particle size distribution, then the process is simple, but the particle size distribution is inconsistent and magnetic performance deteriorates
Solution Approach 1:
The patent introduces a dynamic, multi-parameter control system for ball milling that adjusts milling time, steel ball-to-material ratio, and raw material particle size based on target slurry specifications. This dynamic approach replaces static, single-parameter control, enabling consistent achievement of the required particle size distribution (D0.10: 0.4-0.6 μm, D0.50: 0.8-1.0 μm, D0.90: 1.9-2.0 μm) while maintaining process feasibility.
Solution Approach 2:
The patent implements a feedback mechanism where the particle size distribution of the milled powder is measured and used to adjust subsequent milling parameters. This closed-loop control ensures that the slurry consistently achieves the target particle size distribution, preventing magnetic performance deterioration while maintaining manufacturing simplicity through automated adjustments.
3Productivity
If grouting speed is increased to improve production efficiency, then productivity increases, but bending strength and compressive strength decrease
Solution Approach 1:
The patent performs preliminary optimization of the slurry particle size distribution before the grouting process. By ensuring the slurry has the optimal particle size distribution (D0.10: 0.4-0.6 μm, D0.50: 0.8-1.0 μm, D0.90: 1.9-2.0 μm) and uniformity beforehand, the molded blanks achieve better green strength and structural integrity. This preliminary preparation allows faster grouting speeds to be used without compromising the bending and compressive strength of the final arc magnets.
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 significantly enhances the compressive strength of permanent ferrite arc magnets by improving particle size consistency, reducing lattice defects, and minimizing crack propagation, while maintaining magnetic performance.
Implementation Method 1
transferred to a vertical two-stage cell mill for wet ball milling, to obtain slurry with an average particle size of 0.75 to 0.85 μm
Implementation Method 2
adding a liquid dispersant, stirring uniformly, and then performing magnetic field molding
Implementation Method 3
performing magnetic field molding through a mold to obtain molded blanks
Implementation Method 4
the molded blanks obtained in step (II) being subjected to heat preservation at 300°C, removing moisture and the residual dispersant in the molded blanks, then heating to a sintering temperature under an air atmosphere before being subjected to heat preservation
Data Source
AI summary
Disclosed is a preparation method for improving compressive strength of a permanent ferrite arc magnet, including the following steps: wet ball milling, magnetic field molding, sintering, grinding processing, compressive strength test, and finished product rate calculation. The particle size distribution of a slurry is controlled and the proportion of micro-size particles to large-size particles is reduced, to improve the particle size consistency. The probability of abnormal growth of grains during sintering is reduced, reducing the probability of lattice defects, reducing the grain size, and finally avoiding trans-granular fracture when subjected to bending load, and greatly lengthening a crack path of intergranular fracture, and improving the compressive strength. A self-made liquid dispersant is added to a ferrite slurry before the magnetic field molding to improve the fluidity of the slurry, thereby improving the consistency of the density of an arc magnet blank, making the shrinkage rate of each point of the blank tend to be consistent during sintering, reducing the surface pulling force, avoiding the propagation of micro-cracks caused by the surface pulling force, and finally improving the compressive strength of an arc magnet product and reducing the probability of the cracking of the arc magnet.