Ferromagnetic Amorphous Alloy Ribbon Surface Protrusion Control

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Solution Overview

Problem

Ferromagnetic amorphous alloy ribbons used in transformer cores and other magnetic devices face challenges with low saturation induction, high magnetic losses, reduced ductility, and surface protrusions, which affect their packing factor and manufacturing efficiency.

Innovation Solution

A ferromagnetic amorphous alloy ribbon with a specific composition (Fe a Si b B c C d) is cast with controlled molten alloy surface tension and trace elements like Cu, Mn, and Cr, optimizing the Si and B content to achieve high saturation induction, low magnetic losses, and reduced surface protrusions, while maintaining high ductility and thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If Fe content is increased to achieve higher saturation induction, then saturation induction is improved, but thermal stability degrades

Engineering Contradiction:
Improvesaturation inductionVSAvoidthermal stability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical composition parameters by adding specific elements (Sn: 0.01-3 at.%, S: 0.01-2 at.%, C: 0.01-2 at.%, P: 0.01-2 at.%) to the Fe-Si-B amorphous alloy system. These compositional changes enable achieving saturation induction of 1.65 T or higher while maintaining thermal stability through the synergistic effects of the added elements on the alloy's microstructure and magnetic properties.

Inventive Principle:
Principle #35Parameter changes

2Strength

If Sn, S, C or P elements are added to increase saturation induction and improve formability, then saturation induction is improved, but ductility of the cast ribbon deteriorates

Engineering Contradiction:
Improvesaturation inductionVSAvoidductility
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent precisely controls the concentration parameters of added elements within specific ranges (Sn: 0.01-3 at.%, S: 0.01-2 at.%, C: 0.01-2 at.%, P: 0.01-2 at.%) to achieve the optimal balance between saturation induction and ductility. This parameter optimization ensures that the alloy achieves high saturation induction (≥1.65 T) while maintaining sufficient ductility for practical fabrication of wide ribbons.

Inventive Principle:
Principle #35Parameter changes

3Strength

If P is added to increase saturation induction with increased Fe content, then saturation induction is improved, but long-term thermal stability is lost leading to increased magnetic core loss

Engineering Contradiction:
Improvesaturation inductionVSAvoidlong-term thermal stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent creates a multi-element composite amorphous alloy system (Fe-Si-B-C-Sn-S-P) where multiple elements work synergistically. The combination of C and Sn with limited P content creates a composite structure that achieves high saturation induction while the C and Sn elements compensate for the thermal stability degradation caused by P, preventing magnetic core loss increase over time.

Inventive Principle:
Principle #40Composite materials

4Productivity

If ribbon surface protrusions are reduced to improve packing factor, then manufacturing efficiency is improved, but surface tension control complexity increases

Engineering Contradiction:
Improvepacking factorVSAvoidsurface tension control
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent utilizes the surface tension modifying effects of added elements (particularly S and P) to control the molten alloy's surface tension during casting. By adjusting the concentrations of these elements within specified ranges, the patent achieves reduced surface protrusions and improved ribbon surface quality, thereby increasing packing factor and manufacturing efficiency without requiring complex external control systems.

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

The solution results in a ribbon with a saturation magnetic induction exceeding 1.60 T, low magnetic core loss, and improved thermal stability, enabling efficient and cost-effective manufacturing with enhanced mechanical properties and reduced core losses in magnetic components.

Implementation Method 1

the molten alloy surface tension gradually decreases with the casting time, and the surface protrusions are reduced when the molten alloy surface tension is within a certain range

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP2614509B1Ferromagnetic amorphous alloy ribbon with reduced surface protrusions, method of casting and application thereof
Publication Date: 2020.04.01 METGLAS INC
  • EP2614509B1 patent drawingFigure 1
  • EP2614509B1 patent drawingFigure 2
  • EP2614509B1 patent drawingFigure 3

AI summary

A ferromagnetic amorphous alloy ribbon having a composition represented by FeSibBcCd where 80.5 </= a </= 83 at.%, 0.5 </= b </= f at.%, 12 </= c </= 16.5 at.%, 0.01 </= d </= 1 at. % with a + b + c + d = 100 and incidental impurities. The ribbon being cast from a molten state of the alloy with a surface tension of greater than or equal to 1.1 N/m on a chill body surface; the ribbon having ribbon surface protrusions facing the chill body surface; the protrusion height between 3 micrometers and four times the ribbon thickness, the number of protrusions being less than 10 within 1.5 m of the cast ribbon length. The ribbon is suitable for transformer cores, rotational machines, electrical chokes, magnetic sensors, and pulse power devices.