E-iron oxide powder pH control for dispersion stability

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Solution Overview

Problem

Current methods fail to achieve high temporal dispersion stability for ε-iron oxide type ferromagnetic powders, which is crucial for maintaining the quality and preventing aggregation in various applications.

Innovation Solution

The ε-iron oxide type ferromagnetic powder is manufactured by controlling its pH within a range of 4.8 to 6.8 through specific treatment conditions, including coat-forming, heat treatment, and acid treatment, and the average particle size is maintained within 7.0 to 50.0 nm to enhance dispersion stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ε-iron oxide type ferromagnetic powder is used, then the powder can be manufactured with standard processes, but the powder aggregates over time in composition, resulting in poor temporal dispersion stability

Engineering Contradiction:
Improvetemporal dispersion stabilityVSAvoidaggregation resistance
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by precisely controlling the powder pH within the range of 4.8 to 6.8 through adjusted treatment conditions (coat-forming, coat-removing, and acid treatments). This specific pH range creates optimal surface charge characteristics that prevent particle aggregation over time, thereby improving temporal dispersion stability without requiring changes to the fundamental powder structure or composition.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the powder pH is not controlled within the specific range, then the manufacturing process is simpler, but the powder aggregates over time reducing composition quality

Engineering Contradiction:
Improvetemporal dispersion stabilityVSAvoidpH control precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements feedback control by measuring and adjusting the powder pH through the treatment conditions to ensure it falls within the 4.8 to 6.8 range. This feedback mechanism allows continuous monitoring and adjustment of the pH during manufacturing, ensuring consistent temporal dispersion stability while maintaining manageable manufacturing precision requirements.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transforms the manufacturing approach by introducing precise pH control as a critical parameter. By adjusting treatment conditions (coat-forming agent concentration, acid treatment duration, etc.) to achieve the target pH range of 4.8 to 6.8, the patent converts a simple manufacturing process into one that produces powder with superior temporal dispersion stability through controlled surface chemistry.

Inventive Principle:
Principle #35Parameter changes

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 significantly improves the temporal dispersion stability of the ε-iron oxide type ferromagnetic powder, preventing aggregation and maintaining its quality over time, making it suitable for diverse applications such as magnetic recording and radio wave absorption.

Implementation Method 1

converting the precursor into an ε-iron oxide type ferromagnetic material by performing a heat treatment on the precursor having undergone the coat-forming treatment

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS11367548B2E-iron oxide type ferromagnetic powder, method for manufacturing same, and composition containing e-iron oxide type ferromagnetic powder
Publication Date: 2022.06.21 FUJIFILM CORP

AI summary

Provided is an ε-iron oxide type ferromagnetic powder with a powder pH within a range of 4.8 to 6.8; and a method for manufacturing the ε-iron oxide type ferromagnetic powder and a composition containing at least the ε-iron oxide type ferromagnetic powder and a solvent.