Aluminum Plate Diffusion Bonding for Clean Heat-Exchange Passages
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Solution Overview
Problem
The existing brazing method for joining metal or ceramic composite plates with passages results in quality deterioration due to brazing material flowing into passages, causing surface roughness, flow rate variations, and impurity contamination.
Innovation Solution
A diffusion bonding method is employed to join aluminum or aluminum alloy main bodies and covers, with a joining temperature between 500°C and 640°C and a surface pressure of 0.7 MPa or higher, ensuring flatness and surface roughness within specific limits to prevent quality deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If brazing method is used to join main body and cover, then joining strength is improved, but brazing material flows into passages causing surface roughness and quality deterioration
Solution Approach 1:
The invention changes the joining temperature parameter from conventional brazing temperatures (above melting point of brazing material) to diffusion bonding temperature range (500-640°C), which is below the melting point of aluminum and aluminum alloys. This parameter change eliminates the flow of joining material into passages while maintaining effective joining through atomic diffusion at elevated temperatures
Solution Approach 2:
The invention replaces the brazing process (which uses a filler material that melts and flows) with diffusion bonding (which relies on atomic diffusion across the interface). This substitution eliminates the harmful flow of joining material into passages while achieving reliable joining through direct metallurgical bonding at the interface
2Strength
If brazing method is used to join main body and cover, then joining strength is improved, but impurity contamination occurs due to brazing material components
Solution Approach 1:
The invention replaces brazing with diffusion bonding, substituting a process that introduces foreign brazing material into a process that creates a direct metal-to-metal bond. This eliminates impurity contamination from brazing material components while maintaining joining strength through atomic diffusion and metallurgical bonding
3Manufacturing precision
If diffusion bonding is used with joining temperature of 500-640°C and surface pressure of 0.7 MPa or higher, then passage quality is maintained, but joining reliability is achieved
Solution Approach 1:
The invention establishes specific parameter ranges for diffusion bonding: temperature of 500-640°C (below aluminum melting point but high enough for atomic diffusion) and surface pressure of 0.7 MPa or higher (to ensure intimate contact and promote diffusion). These parameter changes simultaneously achieve passage quality maintenance and reliable joining through controlled atomic diffusion
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 effectively suppresses quality deterioration while reliably joining the main body and cover, maintaining the integrity of the passages and preventing impurity contamination.
Implementation Method 1
a diffusion bonding step of joining the main body and the cover by diffusion bonding under a condition in which a joining temperature is 500° C. or higher and 640° C. or lower, and a joining surface pressure is 0.7 MPa or higher
Data Source
AI summary
A joining method of joins a main body and a cover, the main body being a flat plate and made of aluminum or an aluminum alloy and including a passage through which a medium for promoting heat exchange is circulated, and the cover being a flat plate and made of aluminum or an aluminum alloy and configured to cover the passage of the main body. The method includes: a covering step of covering the main body with the cover; and a diffusion bonding step of joining the main body and the cover by diffusion bonding under a condition in which a joining temperature is 500° C. or higher and 640° C. or lower, and a joining surface pressure is 0.7 MPa or higher. Each of a joining surface of the main body and a joining surface of the cover has a flatness of 0.2 or less.