Metal-enriched paper for sintered metal foil production

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Solution Overview

Problem

The production of sintered metal foils requires organic, volatile solvents, increasing process costs and safety risks, and results in low rigidity and stability due to the lack of fiber reinforcement, making it difficult to create complex geometries.

Innovation Solution

A water-based process using papermaking technology to produce a metal-enriched paper with cellulose fibers as reinforcement, allowing for the creation of a flat, stable, and flexible semi-finished product with high metallic filler content, which can be thermally converted into a metallic material without the need for organic solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If organic solvents are used in sintered metal foil production, then the manufacturing process can be implemented, but process costs increase and safety risks arise

Engineering Contradiction:
Improvemanufacturing process feasibilityVSAvoidprocess costs and safety risks
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of the liquid medium from organic solvent to water-based suspension. This substitution eliminates the harmful effects of organic solvents (cost and safety issues) while maintaining the necessary function of transporting and distributing metal particles during the manufacturing process. The water-based slurry serves as the binding and transporting medium throughout the paper-making process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the chemical-based organic solvent system with a water-based mechanical suspension system. Instead of relying on organic solvents to bind metal particles, the invention uses water as the continuous phase with metal particles suspended throughout, leveraging the paper-making process's mechanical fiber network to provide structural integrity during and after drying.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If sintered metal foils are produced without fiber reinforcement, then the production process is simpler, but rigidity and stability are low, making it difficult to create complex geometries

Engineering Contradiction:
Improveproduction process complexityVSAvoidrigidity and stability
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The patent creates a composite material system combining metal particles with cellulose fibers in a water-based matrix. The cellulose fibers serve as reinforcement, providing the necessary rigidity and stability to the green body before sintering. This composite structure enables the formation of complex geometries while maintaining structural integrity during handling and processing, without significantly complicating the production process since the fibers are incorporated during the standard paper-making operation.

Inventive Principle:
Principle #40Composite materials

3Quantity of substance

If metal-enriched paper is produced with high metallic filler content, then the final metallic material properties are improved, but the paper production process becomes more challenging

Engineering Contradiction:
Improvemetallic filler contentVSAvoidpaper production processability
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent leverages the universal applicability of standard paper-making technology to produce metal-enriched materials. The paper-making process, already optimized for distributing fibers uniformly, is applied to distribute metal particles throughout the matrix. This multi-functional approach allows the incorporation of high metallic filler content (70-95 wt%) while utilizing existing, well-established manufacturing equipment and processes, thereby avoiding the need for specialized complex production lines.

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

Solution Approach 2:

The patent modifies key parameters of the paper-making process to accommodate high metal content: adjusting slurry consistency, controlling fiber-to-metal ratios, and optimizing drying conditions. These parameter changes enable the successful production of metal-enriched paper with 70-95 wt% metallic content while maintaining the processability and uniformity characteristic of conventional paper manufacturing.

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 method enables the production of a cost-effective, stable, and flexible sintered metal semi-finished product that can be easily shaped into complex geometries and thermally converted into a metallic material with precise control over thickness, density, and microstructure, reducing process costs and safety hazards.

Implementation Method 1

A water-based process using papermaking technology to produce a metal-enriched paper

Methodology Applied
Scientific EffectPapermaking technology:

Implementation Method 2

These papers are thermally converted into ceramic materials via pyrolysis and subsequent oxidation

Methodology Applied
Scientific EffectPyrolysis: Pyrolysis

Implementation Method 3

porous sintered metal structures

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP2331610B1Metallic semi-finished product
Publication Date: 2016.04.20 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2331610B1 patent drawingFigure 1~2
  • EP2331610B1 patent drawingFigure 3

AI summary

The object of the invention is a semi-finished product, comprising (a) fibrous materials, (b) binders, (c) 15 to 90 vol.-% metallic fillers and (d) 0 to 15 vol.-% non-metallic inorganic fillers, wherein the total contents of fillers (c) and (d) together does not amount to more than 90 vol-% of the semi-finished product, and wherein all volume fractions refer to the solid volume of the semi-finished product. The invention relates to metallic materials and to a method for producing the materials and semi-finished products and to the uses thereof.