Clad Heat Exchanger Sheets for Marine Corrosion and Roll Bonding
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Solution Overview
Problem
Metal corrosion, particularly in marine environments, is a significant challenge for heat exchangers due to the aggressive nature of seawater, and existing corrosion-resistant alloys are often expensive and not suitable for roll-bonding processes.
Innovation Solution
The development of aluminum alloy materials with a corrosion-resistant core and low-magnesium cladding, either one-sided or two-sided, allows for roll-bonding to create heat exchangers with enhanced corrosion resistance by controlling metallurgical bonding and incorporating scrap metal, thereby overcoming the limitations of traditional alloys in marine environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If corrosion-resistant alloys with high magnesium content are used, then corrosion resistance in marine environments is improved, but roll-bonding becomes difficult due to uncontrolled Mg-oxide generation
Solution Approach 1:
The alloy is segmented into a core layer (providing corrosion resistance with high Mg content) and a cladding layer (enabling roll-bonding with low Mg content). This segmentation allows each layer to have optimized properties for its specific function, resolving the contradiction between corrosion resistance and manufacturability.
Solution Approach 2:
A composite clad sheet structure is created combining a corrosion-resistant core alloy with a roll-bonding-compatible cladding alloy. The composite material integrates the advantages of both alloys: the core provides marine corrosion resistance while the cladding enables successful roll-bonding without excessive oxide formation.
2Reliability
If traditional corrosion-resistant alloys are used, then corrosion protection is improved, but material cost increases significantly
Solution Approach 1:
Corrosion resistance is applied locally where needed through the core layer that contacts the marine environment, while the cladding layer focuses on manufacturability. This localized quality distribution optimizes material costs by providing corrosion protection only in the necessary regions rather than requiring expensive corrosion-resistant materials throughout the entire structure.
Solution Approach 2:
The magnesium content parameter is changed and distributed differently across the alloy structure: high Mg (3-12%) in the core for corrosion resistance, low Mg (0.01-0.5%) in the cladding for cost-effective roll-bonding. This parameter variation allows cost optimization while maintaining performance.
3Strength
If high magnesium content alloys are used for roll-bonding, then metallurgical bonding is improved, but uncontrolled Mg-oxide generation occurs at the bond interface
Solution Approach 1:
The cladding layer acts as a sacrificial, low-Mg barrier that prevents excessive oxide formation during roll-bonding. This disposable outer layer protects the core during the bonding process, enabling strong metallurgical bonds without the harmful oxide generation that would occur with high-Mg alloys.
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 provides high corrosion resistance and cost-effective production of heat exchangers suitable for marine environments, utilizing roll-bonding techniques to create clad sheet alloys that can withstand seawater exposure while maintaining ease of fabrication and incorporating high scrap metal content.
Implementation Method 1
a metal alloy cladding which is fusion-cast to the metal alloy core to form a one side clad sheet
Implementation Method 2
The metal alloy cladding is selected for ease of roll bonding. In this example the clad layers of two, one side clad sheets are roll bonded to each other to produce an integral tube, twin plate heat exchanger
Implementation Method 3
This roll bonding process produces a permanent metallurgical bond between regions of the clad layer of the first sheet and the clad layer of the second sheet
Data Source
AI summary
This application discloses a material including an aluminum metal alloy cladding fusion-cast to a metal alloy core. Also disclosed is a material having a metal core with a high content of scrap metal and having two sides, a first aluminum metal cladding fusion cast to the first side of the core layer, and a second aluminum metal cladding fusion cast to the second side of the core layer. The materials can be in a form of a sheet. Sheets are roll bonded together to create permanent metallurgical bonds except at regions where a weld-stop ink is applied. The sheets are used to make corrosion resistant heat exchangers.