Silicon Oxide Coating for Metal Powder Without Organic Solvents
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Solution Overview
Problem
The use of organic solvents in the manufacturing of silica-coated soft magnetic powders for dust cores increases the production cost due to the procurement and treatment costs, and there is a need for a more efficient and cost-effective method to form a dense silicon oxide coating that enhances insulating and heat-resistant properties.
Innovation Solution
A method involving the use of an alkaline aqueous solution to dissolve a silicon-containing substance, forming a silanol solution, dispersing metal powder in it, and adding an acidic aqueous solution to create a silicon oxide coating on the metal powder surface without using organic solvents, optimizing pH levels to control coating density and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvent is used together with tetraethoxysilane to prepare the hydrolyzed solution, then the silica film can be formed on the metal powder surface, but the manufacturing cost increases due to procurement and treatment of organic solvent
Solution Approach 1:
The patent extracts and removes the organic solvent component from the hydrolyzed solution system, replacing it with an aqueous solution containing silane coupling agent. This eliminates the harmful organic solvent while maintaining the essential coating formation function, directly resolving the contradiction between coating quality and manufacturing cost by removing the expensive and problematic substance entirely
Solution Approach 2:
The patent changes the fundamental parameter of the solution medium from organic-based to water-based. By adjusting the pH value and using aqueous solutions instead of organic solvents, the system achieves the same coating formation effect without the cost and environmental burden of organic solvents, resolving the contradiction through parameter transformation
2Reliability
If organic solvent is used in the hydrolyzed solution, then the silica film formation process can proceed, but wastewater treatment becomes necessary increasing production cost
Solution Approach 1:
The patent converts the harmful organic solvent into a beneficial aqueous solution system. By using water as the base and silane coupling agents that hydrolyze in water, the process transforms a harmful waste stream into a benign or even useful byproduct (water-soluble residues that are easier to treat), eliminating the need for complex organic solvent treatment while maintaining coating formation capability
Solution Approach 2:
The patent replaces expensive and environmentally problematic organic solvents with inexpensive, easily treatable aqueous solutions. The water-based system can be disposed of or treated through simple evaporation or biological treatment, eliminating the need for costly specialized organic solvent treatment facilities
3Reliability
If heat treatment at high temperature of 800° C. or higher is applied, then crystal grain size increases and processing strain is removed reducing hysteresis loss, but the coating may be damaged or degraded
Solution Approach 1:
The patent applies preliminary action by forming a robust silica coating through controlled hydrolysis and condensation before the heat treatment process. The coating is pre-formed with adequate thickness and cross-linking to withstand the subsequent high-temperature treatment, preventing metal powder oxidation while allowing the bulk material to undergo necessary crystal grain growth and strain relief
Solution Approach 2:
The patent creates a composite structure where the silica coating and metal powder core work together. The silica layer acts as a protective barrier that enables the metal powder to withstand high-temperature heat treatment without oxidation, while the composite structure maintains coating integrity through proper interface bonding achieved through silane coupling agent chemistry
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 method reduces manufacturing costs by eliminating the need for organic solvents and wastewater treatment, while achieving a dense silicon oxide coating with high insulating and heat-resistant properties, maintaining these properties even after heat treatment.
Implementation Method 1
preparing a silanol solution in which a silicon-containing substance is dissolved in an alkaline aqueous solution
Implementation Method 2
forming a coating containing a silicon oxide on a particle surface of the metal powder by adding an acidic aqueous solution to the dispersion
Data Source
AI summary
A method for manufacturing a coated metal powder includes: preparing a silanol solution in which a silicon-containing substance is dissolved in an alkaline aqueous solution; charging a metal powder into the silanol solution to obtain a dispersion; and forming a coating containing a silicon oxide on a particle surface of the metal powder by adding an acidic aqueous solution to the dispersion.