Anti-diffusion Microstructures in Sheet Metal for Soldering
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Solution Overview
Problem
Existing metallic honeycomb bodies face issues with unwanted diffusion bonding during high-temperature soldering processes, leading to stiffness and inelasticity, which complicates the production of honeycombs with specific properties and service life requirements.
Innovation Solution
A sheet metal layer with anti-diffusion microstructures, designed to be corrosion-resistant and flexible, is used to create precise soldered connections between smooth and corrugated layers, preventing unwanted diffusion bonds by ensuring microstructures protrude on both sides and are spaced to allow only specific contact points for soldering, thereby controlling the soldering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature soldering is used to join sheet metal layers, then strong soldered connections are achieved, but unwanted diffusion bonds form between contact points
Solution Approach 1:
The invention segments the contact areas between sheet metal layers by introducing microstructures (protrusions and recesses) that divide continuous contact surfaces into discrete, isolated contact points. This segmentation prevents diffusion bonds from forming across extended contact areas, while still allowing strong soldered connections at the specific segmented contact points during high-temperature soldering.
Solution Approach 2:
The invention applies local quality by creating microstructures with specific protrusions and recesses at predetermined locations on the sheet metal layers. These microstructures locally modify the contact characteristics, ensuring that soldering occurs only at specific desired locations while preventing unwanted diffusion bonding at other contact areas.
2Manufacturing precision
If microstructures are added to sheet metal layers to prevent diffusion bonding, then soldering precision is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges the functions of diffusion prevention and soldering guidance into a single integrated microstructure design. The same protrusions and recesses that prevent unwanted diffusion bonding also serve as the precise locations for desired soldered connections, eliminating the need for separate diffusion barrier layers or complex masking processes.
Solution Approach 2:
The invention changes the surface geometry parameters of the sheet metal layers by introducing controlled microstructures with specific height, width, and spacing parameters. These parameter changes create the necessary contact point isolation for preventing diffusion while maintaining manufacturability through standard forming processes.
3Reliability
If sheet metal layers are made smooth for coating applications, then coating quality is improved, but diffusion bonding occurs more easily during soldering
Solution Approach 1:
The invention resolves the contradiction by transitioning from a two-dimensional surface smoothness consideration to a three-dimensional microstructure approach. The microstructures extend in the depth dimension with controlled heights, allowing the top surfaces to remain smooth for coating while the vertical structures prevent continuous contact and diffusion bonding during assembly.
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 precise control of soldered connections, preventing undesirable diffusion bonds and allowing for the production of honeycombs with tailored properties and extended service life, even under extreme loads, while maintaining smoothness for coating applications.
Implementation Method 1
such high temperatures are used, for example above 1100 °C, that diffusion bonds form between the contact points of metal sheets
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a sheet-metal layer (1) having anti-diffusion structures made of a high-temperature-corrosion-resistant steel, having a longitudinal direction (Q) and a top side (2) and a bottom side (3) and a thickness (d) of 0.015 to 0.1 mm, wherein the sheet-metal layer (1) comprises discontinuous microstructures (4, 5) extending approximately in the longitudinal direction (Q) and having the following characteristics: a. the microstructures (4, 5) have a structure height (SH), a structure length (SL), and a structure width (SB) and among each other a distance (LA) to the nearest microstructure (4,5) aligned approximately in the longitudinal direction thereof, said distance being formed by interruptions (6), and a lateral distance (SA) to the nearest laterally adjacent microstructure (4, 5); b. the microstructures (4, 5) are designed so that some of the microstructures project out of the sheet-metal layer (1) toward the top side (2) and some of the microstructures project out of the sheet-metal layer toward the bottom side (3); c. the microstructures (4, 5) are spaced, arranged, and designed in such a way that each straight theoretical line (G) extending across the sheet-metal layer (1) perpendicularly to the longitudinal direction (Q) intersects with at least two microstructures (4, 5) projecting toward the top side (2) and two microstructures projecting toward the bottom side (3); wherein d. the following relations apply: the structure height (SH) is 0.02 to 0.1 mm, preferably 0.06 to 0.08 mm, the structure length (SL) is 2 to 10 mm, preferably 4 to 6 mm, the structure width (SB) is 0.2 to 1 mm, preferably approximately 0.5 mm, the longitudinal distance (LA) to the nearest microstructure aligned approximately in the longitudinal direction thereof is greater than 2 mm, preferably 4 to 8 mm, the lateral distance (SA) to the nearest laterally adjacent microstructure (4, 5) is 1 to 10 mm, preferably 2 to 6 mm.