Graphite-Metal Diffusion Bonding via Silver Penetration
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Solution Overview
Problem
Existing methods for connecting graphite layers to metal supports often compromise the mechanical, thermal, electrical, and chemical properties of graphite, either through mechanical damage, adhesive layer limitations, or high production costs, especially under thermal and mechanical stress.
Innovation Solution
A method involving a diffusion step where a silver adhesion layer penetrates into both the graphite and carrier metal layers, forming a strong, conductive, and chemically stable connection without the need for adhesives or mechanical interlocking, with the silver remaining in the solid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fixing is used to bond graphite layer to metal substrate, then bonding strength is improved, but graphite layer properties are damaged
Solution Approach 1:
The patent replaces mechanical fixing (physical interlocking) with a chemical bonding mechanism. The metal substrate surface is activated to form chemical bonds with graphite, eliminating the need for mechanical interlocking that causes physical damage to the graphite layer structure.
Solution Approach 2:
The patent changes the bonding mechanism from mechanical to chemical by modifying the surface properties of the metal substrate through activation treatments. This parameter change allows bonding without the physical deformation and damage associated with mechanical fixing methods.
2Strength
If adhesive bonding is used to connect graphite and metal substrate, then bonding is achieved, but chemical and thermal stability deteriorates
Solution Approach 1:
The patent removes the adhesive layer from the bonding system entirely. By directly bonding the activated metal substrate surface to the graphite, it eliminates the adhesive that causes chemical contamination and thermal decomposition issues.
Solution Approach 2:
The patent uses the activated metal substrate surface itself as the intermediary bonding interface rather than introducing a separate adhesive material. This direct bonding approach maintains chemical and thermal stability while achieving strong adhesion.
3Strength
If vacuum brazing is used to join graphite and metal, then bonding strength is improved, but process complexity increases
Solution Approach 1:
The patent changes the bonding process parameters by using surface activation at lower temperatures compared to vacuum brazing. This allows achieving strong bonds without requiring vacuum conditions or extremely high temperatures, thereby simplifying the overall process.
Solution Approach 2:
The patent replaces the complex vacuum brazing process with a simpler surface activation and direct bonding approach. This substitution eliminates the need for vacuum equipment and complex process controls while maintaining bonding effectiveness.
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 achieves a connection that is stronger than the inherent strength of graphite under thermal and mechanical stress, maintaining excellent electrical and thermal conductivity while being chemically stable, with reduced material usage and production costs, and avoiding the limitations of adhesive and mechanical fixing methods.
Implementation Method 1
the bonding includes a diffusion step in which the at least one metal of the adhesive layer is excited to penetrate at least partially into the graphite layer and the carrier metal layer
Data Source
Figure 1
AI summary
The invention relates to a method for producing a connection (5) between a carrier metal layer (1) and a graphite layer (3). According to the invention, said method comprises the following steps: providing a carrier metal layer (1); providing a graphite layer (3) to be connected to the carrier metal layer (3); arranging a bonding layer (2) comprising at least one metal (4) between the carrier metal layer (1) and the graphite layer (3); connecting the carrier metal layer (1) to the graphite layer (3), wherein the connection comprises a diffusion step wherein the metal (4) is stimulated to penetrate at least partially into the graphite layer (3) and/or the carrier metal layer (1), wherein the metal substantially remains in a fixed phase.