Neutral pH Weld Cleaning Fluid for Stainless Steel Passivation
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Solution Overview
Problem
Existing weld cleaning fluids for stainless steel, typically acidic in nature, pose environmental and safety hazards during disposal and use, and often require careful handling, while also being inefficient in achieving a smooth finish and quick passivation.
Innovation Solution
A neutral pH weld cleaning fluid composition using sodium and/or potassium orthophosphate as the main active ingredient, along with a sequestering agent like EDTA, applied with a low voltage high current electrical current and a conductive brush to remove weld tint and passivate stainless steel surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional acidic cleaning fluids (phosphoric acid) are used for weld cleaning, then cleaning effectiveness is achieved, but environmental hazards and safety risks increase
Solution Approach 1:
The patent changes the pH parameter of the cleaning fluid from acidic (traditional phosphoric acid) to neutral (using phosphates such as tripotassium phosphate). This parameter change maintains cleaning effectiveness while eliminating the harmful effects associated with acidic fluids, including environmental hazards and safety risks to workers
Solution Approach 2:
The patent converts the harmful acidic property into a beneficial neutral property by using phosphate-based cleaners. The neutral pH eliminates corrosion risks to equipment, safety hazards to workers, and environmental disposal problems while maintaining the cleaning function through alternative chemical mechanisms
2Ease of manufacture
If acidic cleaning fluids are used, then weld discoloration is removed, but surface roughening occurs
Solution Approach 1:
The patent changes the chemical nature of the cleaning agent from acidic to neutral phosphate-based formulation. This parameter change alters the mechanism of action from acid etching to a gentler cleaning process that removes discoloration without roughening the metal surface, thereby improving surface finish quality
3Object-affected harmful factors
If neutral pH cleaning fluid is used, then safety and environmental issues are resolved, but cleaning speed may be reduced
Solution Approach 1:
The patent introduces phosphates (such as tripotassium phosphate) as intermediary substances that enable effective cleaning at neutral pH. These phosphate intermediaries facilitate the removal of weld discoloration and provide passivation benefits without requiring acidic conditions, thus maintaining cleaning speed while ensuring safety and environmental compliance
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 neutral pH fluid effectively removes weld discoloration and passivates stainless steel surfaces quickly, reducing environmental and safety concerns, and providing a superior finish compared to traditional acidic fluids, while being safer for workers and more economical.
Implementation Method 1
the removal of exogenous iron or iron compounds from the surface of stainless steel by means of a chemical dissolution
Implementation Method 2
oxidising the chromium atoms present to form the new surface layer
Implementation Method 3
The tool heats and passivates the metal surface
Implementation Method 4
electro-chemical cleaning or polishing has been utilised
Data Source
AI summary
The invention relates to a weld cleaning fluid, and method of cleaning weld or discoloration especially on stainless steel. Stainless steel welds, such as those done by TIG welding, require cleaning to remove the resulting surface discoloration and also to passivate the steel. This is often done using an electro-cleaning apparatus with the assistance of electrolyte cleaning fluids. A new cleaning fluid has been developed that has a generally neutral pH, instead of the highly acidic nature of previously used fluids, which avoids environmental and safety issues. The cleaning fluid composition preferably has potassium or sodium orthophosphate salts as the main active ingredient, or similar such salts, and has a pH of around 7. It may also include a sequestering or chelating agent such as a sodium and/or potassium salt of EDTA, and coloring and fragrance.