MnZn Ferrite Core Production for Low High-Frequency Loss
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Solution Overview
Problem
Current methods for producing MnZn ferrite cores do not adequately reduce core loss across a wide temperature range, especially at high frequencies and magnetic flux densities, which affects the efficiency and stability of power supply circuits in electronic devices.
Innovation Solution
A method involving the production of MnZn ferrite cores with specific compositions and processing steps, including molding, sintering, and heat treatment, to achieve reduced core loss. The method involves sintering at controlled temperatures and cooling speeds, and heat treatment within specific temperature ranges to optimize magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional sintering and cooling methods are used, then production efficiency is maintained, but core loss cannot be sufficiently reduced across a wide temperature range
Solution Approach 1:
The patent applies parameter changes by precisely controlling sintering temperature (1000-1200°C), cooling rates (5-50°C/min), and heat treatment temperatures (150-450°C) to optimize the microstructure of MnZn ferrite. These parameter adjustments reduce core loss across a wide temperature range while maintaining production feasibility
Solution Approach 2:
The patent implements preliminary action through a multi-step process: first sintering to form the base structure, then controlled cooling to establish initial microstructure, and finally heat treatment to optimize magnetic properties. This sequential preparation ensures low core loss before the core enters service
2Volume of moving object
If high frequency operation is implemented, then device size is reduced, but core loss increases at high temperatures
Solution Approach 1:
The patent changes material parameters by optimizing MnO (40-50 mol%), ZnO (5-15 mol%), and Fe2O3 (40-55 mol%) composition ratios, along with controlling crystal grain size (3-8 μm) through thermal processing. These parameter optimizations enable high-frequency operation with reduced core loss at elevated temperatures
Solution Approach 2:
The patent creates a composite microstructure consisting of MnZn ferrite crystal grains embedded in a glassy phase matrix. This composite structure combines the magnetic properties of ferrite with the insulating and stabilizing characteristics of the glassy phase, reducing eddy current loss and improving high-temperature stability
3Loss of energy
If crystal grain size is reduced to lower core loss, then high frequency performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent controls crystal grain size (3-8 μm) by adjusting sintering temperature (1000-1200°C) and holding time (2-6 hours), creating a narrow but achievable parameter window that balances grain refinement with manufacturing practicality
Solution Approach 2:
The patent introduces a glassy phase as an intermediary that forms at grain boundaries during sintering. This glassy phase acts as a natural grain boundary phase that limits grain growth, enabling consistent crystal grain size control without requiring extremely precise manufacturing conditions
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 results in MnZn ferrite cores with significantly reduced core loss, achieving lower power consumption and improved stability across a wide temperature range, suitable for high-frequency applications in electronic devices.
Implementation Method 1
a step of sintering the green body and cooling it to a temperature of lower than 150° C. to obtain a sintered body of MnZn ferrite
Implementation Method 2
a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting the following conditions: Condition 1: 200° C. or higher, and Condition 2: (Tc−90)° C. to (Tc+100)° C.
Implementation Method 3
cooling the sintered body from the keeping temperature at a speed of 50° C./hour or less
Data Source
AI summary
A method for producing a MnZn ferrite core used at a frequency of 1 MHz or more and an exciting magnetic flux density of 75 mT or less, the MnZn ferrite comprising 53-56% by mol of Fe (calculated as Fe2O3), and 3-9% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and 0.05-0.4 parts by mass of Co (calculated as Co3O4) as a sub-component, per 100 parts by mass in total of the main components (calculated as the oxides); comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body; a step of sintering the green body and cooling it to a temperature of lower than 150° C. to obtain a sintered body of MnZn ferrite; and a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting Condition 1 of 200° C. or higher, and Condition 2 of (Tc−90)° C. to (Tc+100)° C., wherein Tc is a Curie temperature (° C.) calculated from the percentages by mol of Fe2O3 and ZnO contained in the main components of the MnZn ferrite, keeping the sintered body at the above temperature for a predetermined period of time, and then cooling the sintered body from the keeping temperature at a speed of 50° C./hour or less.