Water-Atomized Metal Powder Quenching for High-Fe Amorphous Density
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Solution Overview
Problem
Conventional water atomization processes struggle to produce metal powders with high amorphous proportions and apparent densities necessary for low iron loss and high magnetic flux density, especially when the concentration of Fe-group elements exceeds 82.9 at%, due to limitations in cooling rates and particle shape formation.
Innovation Solution
The method involves spraying primary cooling water at a convergence angle of 10° to 25° from multiple directions onto a vertically falling molten metal stream, followed by secondary cooling with high-pressure water, to achieve an amorphous proportion of 90% or more and an apparent density of 3.0 g/cm³ or more, even with high Fe concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is sprayed onto molten steel to increase cooling rate, then amorphization is improved, but vapor film formation impedes direct contact and reduces cooling efficiency
Solution Approach 1:
The patent applies preliminary action by pre-heating the water before spraying it onto the molten steel. This pre-heating prevents immediate vaporization and vapor film formation, allowing the water to maintain direct contact with the molten steel surface for more effective heat transfer and amorphization.
Solution Approach 2:
The patent changes the temperature parameter of the water from ambient to pre-heated state. This parameter change transforms the water's thermal state to match the molten steel temperature more closely, preventing the harmful vapor film effect while maintaining efficient cooling for amorphization.
2Quantity of substance
If Fe-group element concentration is increased to increase magnetic flux density, then magnetic performance is improved, but rapid quenching becomes more difficult to achieve
Solution Approach 1:
The patent changes the temperature parameter of the cooling water from ambient to pre-heated state, which enables effective heat extraction from high Fe-concentration molten steel that would otherwise be difficult to quench rapidly enough for amorphization.
Solution Approach 2:
The pre-heating of water before contact with molten steel is a preliminary action that prevents vapor film formation, ensuring that the quenching process can proceed effectively even for high Fe-concentration alloys that require extremely rapid cooling.
3Productivity
If conventional water atomization is used for high Fe concentration metal powder, then productivity is maintained, but amorphous proportion and apparent density are insufficient
Solution Approach 1:
The patent changes the temperature parameter of the water from ambient to pre-heated state, which fundamentally improves the heat transfer efficiency and enables achieving 90% or more amorphous proportion while maintaining continuous production capability.
Solution Approach 2:
The pre-heating of water before atomization is a preliminary action that prevents vapor film formation during the atomization process, ensuring consistent amorphization throughout production without compromising productivity.
4Temperature
If cooling rate is increased for high Fe concentration, then amorphization is improved, but vapor film formation makes direct contact difficult
Solution Approach 1:
The patent changes the water temperature parameter to pre-heated state, which eliminates the thermal shock that causes vapor film formation. This enables direct contact between water and molten steel surface, making the cooling process easier to control and more effective.
Solution Approach 2:
Pre-heating the water before contact is a preliminary action that prevents the harmful vapor film effect, making it easier to achieve and maintain direct contact between cooling water and molten steel surface for effective amorphization.
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 enables the production of water-atomized metal powders with enhanced amorphous proportions and densities, leading to increased magnetic flux density and improved motor performance, while maintaining low costs and high productivity.
Implementation Method 1
When water comes into contact with molten steel, water instantaneously evaporates and forms a vapor film around the molten steel to reach the film boiling state
Implementation Method 2
As the concentration of Fe-group elements increases for the purpose of increasing the magnetic flux density, further rapid quenching is required
Data Source
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AI summary
Provided is a production method for water-atomized metal powder whose amorphous proportion and apparent density can be increased by a low-cost high-productivity water atomization process even if the metal powder has iron (Fe) concentration of 82.9 at% or more and 86.0 at% or less. The production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream is higher than the melting point by 100°C or more, spraying primary cooling water from a plurality of directions at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream of the primary cooling water from one direction among a plurality of the directions and an impact direction on the molten metal stream of the primary cooling water from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point + 50°C) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.