Atmospheric Plasma Passivation for Dishwasher Weld Seam Corrosion
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Solution Overview
Problem
Existing methods for passivating metal surfaces of household appliances, such as phosphating and chromating, require wet-chemical processes that are costly, inefficient, and difficult to apply to specific surface areas, especially in areas like weld seams, leading to incomplete corrosion protection and increased production costs.
Innovation Solution
The use of an atmospheric plasma jet to apply an acidic passivating agent directly to the metal surface, allowing for the deposition of passivating salts like phosphates or chromates, which provides even coverage and reduces the need for post-processing, while being more cost-effective and adaptable to specific surface areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet-chemical passivation methods (phosphating, chromating) are used, then corrosion protection is achieved, but the process requires expensive equipment, high material costs, and cannot treat specific surface areas selectively
Solution Approach 1:
The patent replaces wet-chemical immersion processes with a plasma-based physical-chemical method. An atmospheric plasma jet is used to activate the metal surface, followed by application of a passivating agent that reacts with the activated surface. This substitution eliminates the need for complex wet-chemical equipment while achieving equivalent or superior corrosion protection.
Solution Approach 2:
The plasma jet method enables selective treatment of specific surface areas, such as weld seams, without treating the entire component. The plasma jet can be precisely directed at localized areas requiring corrosion protection, allowing definable surface areas to be treated separately according to their specific needs.
2Reliability
If wet-chemical passivation is applied to entire components, then corrosion protection is achieved, but material waste increases and cost rises
Solution Approach 1:
The plasma jet enables precise localization of the passivation process to only those areas requiring protection, such as weld seams. This selective application dramatically reduces the amount of passivating agent consumed compared to treating entire components, while still achieving adequate corrosion protection where needed.
Solution Approach 2:
The invention extracts the passivation process from the bulk component treatment approach and applies it only to specific problematic areas like weld seams. This extraction of the essential function (corrosion protection) from unnecessary areas reduces material waste while maintaining protection where it matters most.
3Reliability
If wet-chemical processes are used for passivation, then corrosion protection is achieved, but the process cannot treat specific surface areas separately and requires multiple work steps
Solution Approach 1:
The plasma jet method allows different surface areas to be treated with different parameters or at different times based on their specific requirements. Weld seams can be treated with higher energy plasma and different passivating agent concentrations compared to base metal areas, optimizing protection for each zone while streamlining the overall process.
Solution Approach 2:
The plasma jet activates the metal surface before applying the passivating agent, creating a reactive surface that enhances subsequent passivation. This preliminary plasma treatment step prepares the surface in advance, allowing the passivating agent to react more effectively and reducing the need for multiple subsequent processing steps.
4Adaptability or versatility
If atmospheric plasma jet with acidic passivating agent is used, then selective surface treatment is achieved with reduced material waste, but new equipment and process knowledge are required
Solution Approach 1:
The patent uses atmospheric plasma jet technology, which operates at ambient pressure and does not require vacuum systems. This substitution of vacuum-based plasma methods with atmospheric plasma simplifies the equipment requirements while maintaining the ability to perform selective surface treatment with precise control.
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 efficient and uniform passivation of metal surfaces, including weld seams, with reduced material waste and processing steps, enhancing corrosion protection and simplifying the manufacturing process for household appliances like dishwashers.
Implementation Method 1
a passivating salt is deposited on the metal surface of the wall part of the household appliance by the reaction of the acidic passivating agent with the metal surface of the wall part of the household appliance
Implementation Method 2
an atmospheric plasma jet is generated by electrical discharge in a working gas, in which an acidic passivating agent is introduced into the plasma jet
Data Source
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AI summary
Passivating a metal surface (A), preferably a metal surface of a wall part of a household appliance, preferably a metal surface of a wall part of a domestic dishwasher (100), comprises: generating an atmospheric plasma beam (26) in a working gas by an electric discharge; passing an acid-containing passivating agent (120) into the plasma beam; and applying the passivating agent-containing plasma beam to the metal surface, where a passivating salt is deposited on the metal surface by reacting the acidic passivating agent with the metal surface. An independent claim is also included for household appliance, preferably domestic dishwasher, household washing machine, or household dryer comprising at least one wall part, which at least partially comprises a corrosion-resistant metal, preferably a stainless steel, where at least one metal surface of a wall part is at least partially, preferably completely provided with a passivating salt.