Iron-Based Brazing Composition with Fluorescent Verification

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Solution Overview

Problem

Existing iron-based brazing compositions and methods for joining heat transfer plates in plate heat exchangers do not consistently produce durable products with optimal bonding strength, as the proper wetting of brazing material on plate surfaces is often inconsistent due to variations in material type and application methods.

Innovation Solution

An iron-based brazing composition with a specific alloy composition, including 9-30 wt% Cr, 0-5.0 wt% Mn, 0-30 wt% Ni, 0-12 wt% Mo, 0-1 wt% N, 1-20 wt% Si, and optional elements, combined with a binder system and a fluorescent substance for accurate ejection and verification, is used to ensure proper application and consistent quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If iron-based brazing material is used for brazing plate heat exchangers, then brazing can be accomplished, but the bonding strength and durability are inconsistent and not optimal

Engineering Contradiction:
Improvebonding strengthVSAvoidwetting consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the chemical composition parameters of the iron-based brazing material, including carbon content (0.03-0.25%), silicon content (0.5-3.0%), and ranges for Cr, Mn, Ni, Mo, and other elements. This compositional parameter optimization ensures consistent wetting behavior and bonding strength across different production batches, resolving the inconsistency issue.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by adding specific elements at controlled concentrations to targeted regions of the brazing material chemistry. For example, boron (0-2.0%) and phosphorus (0-15%) are added in specific amounts to enhance wetting at the brazing interface, while maintaining overall material integrity. This localized compositional optimization improves wetting consistency without compromising overall reliability.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If different types of brazing materials are used, then various brazing requirements can be met, but the application method must be optimized for each type which increases complexity

Engineering Contradiction:
Improvebrazing material selectionVSAvoidapplication method optimization
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by developing a single iron-based brazing material composition that can serve multiple functions and be applied through a standardized method. The optimized composition with specific ranges for Cr (9-30%), Ni (0-30%), Si (1-20%), and other elements provides consistent performance across different plate heat exchanger designs, eliminating the need for separate optimization procedures for different material types.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent applies composite materials by creating a multi-element iron-based alloy system that combines the beneficial properties of various elements. The composite composition includes Fe as base metal with controlled additions of Cr, Mn, Ni, Mo, Si, B, P, and optional elements, where each component contributes specific properties that collectively provide both versatility and simplified application.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If the brazing material is applied without verification, then the process is simpler, but the quality and consistency of the brazing cannot be ensured

Engineering Contradiction:
Improvebrazing qualityVSAvoidapplication verification
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies feedback by incorporating fluorescent substances into the iron-based brazing material composition. This allows the applied brazing material to be visually verified through fluorescence, providing immediate feedback on application quality and consistency. The fluorescent indicator enables operators to confirm proper coating distribution and thickness without complex measurement equipment, ensuring manufacturing precision while maintaining process simplicity.

Inventive Principle:
Principle #23Feedback

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 enables accurate and consistent application of the brazing composition, ensuring high-quality bonding between heat transfer plates, which enhances the durability and reliability of plate heat exchangers by ensuring proper wetting and uniform application.

Implementation Method 1

a fluorescent substance, for allowing verification of a pattern of applied iron-based brazing composition

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 2

the plates are heated such that the brazing material melts with the result that the plates are brazed together

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

it is required that the brazing material properly wets (comes into contact with) the surfaces and contact points of the plates when the plates are brazed together

Methodology Applied
Scientific EffectWetting: Wetting

Data Source

PatentEP2574420B1Iron-based brazing composition and method of joining heat transfer plates
Publication Date: 2014.10.22 ALFA LAVAL CORP AB
  • EP2574420B1 patent drawingFigure 1~4
  • EP2574420B1 patent drawingFigure 3

AI summary

An iron-based brazing composition comprising an alloy which contains Fe in an amount that balances the alloy, a binder system, and a fluorescent substance for allowing verification of a pattern of applied brazing composition. A method using the iron-based brazing composition comprises iteratively (209), until a predetermined number of heat transfer plates have been stacked: ejecting (203) the brazing composition in a predetermined pattern (Spre); illuminating (204) the ejected composition; registering (205) a pattern (Sreg) of fluorescent light emitted by the fluorescent substance in the composition; comparing (206) the registered pattern (Sreg) with a reference pattern (Sref); and stacking (207) a further heat transfer plate on top of the heat transfer plate on which the composition was ejected. After the number of heat transfer plates have been stacked the stack is heated (211) to a brazing temperature.