Acidic Fluoride Vibratory Grinding for Aluminum Passivation
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Solution Overview
Problem
Existing vibratory finishing methods for metallic components, particularly those made of aluminum, magnesium, and zinc, fail to provide effective adhesion-promoting passivation, leading to inadequate surface preparation for structural bonding and coating applications, and are hindered by the formation of phosphate sludge in alkaline media.
Innovation Solution
An acidic aqueous composition with complex fluorides of boron, silicon, titanium, or hafnium, within specific pH and concentration ranges, is used as a vibratory finishing medium to achieve adhesion-promoting passivation, eliminating phosphate content and enhancing surface tension for improved bonding and coating adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alkaline vibratory finishing media are used, then cleaning and dispersing capacity is improved, but adhesion-promoting passivation is insufficient and phosphate sludge is formed
Solution Approach 1:
The patent changes the pH parameter from alkaline to acidic range (pH 1-4) and replaces phosphate-based chemistry with fluoride-based chemistry, fundamentally altering the chemical environment to achieve both effective cleaning and adhesion-promoting passivation without sludge formation
Solution Approach 2:
The patent introduces fluorosulfonic acid as an intermediary substance that mediates between the cleaning function and passivation function, enabling the acidic medium to both clean effectively and promote adhesion without the harmful side effects of alkaline or phosphate-based systems
2Reliability
If phosphate-containing media are used for passivation, then surface passivation is achieved, but phosphate sludge formation occurs and adhesion is compromised
Solution Approach 1:
The patent converts the potentially harmful acidic environment into a beneficial medium by using fluorosulfonic acid and complex fluorides that promote passivation and adhesion while preventing sludge formation, transforming what could be a corrosive hazard into a controlled surface treatment benefit
Solution Approach 2:
The patent extracts and eliminates phosphate compounds from the vibratory finishing medium, removing the source of sludge formation while maintaining passivation functionality through fluoride-based chemistry
3Ease of operation
If mechanical-chemical pre-treatment is performed, then surface roughness and surface tension are improved for bonding, but additional processing steps are required
Solution Approach 1:
The patent merges the vibratory finishing process with adhesion-promoting passivation into a single integrated operation, eliminating the need for separate mechanical pre-treatment steps while achieving superior surface preparation for bonding and coating applications
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 method effectively promotes adhesion and corrosion protection on aluminum, magnesium, and zinc surfaces, ensuring successful structural bonding and coating applications while avoiding phosphate sludge formation, with surface tensions exceeding 36 mN/m for enhanced wetting and coating adherence.
Implementation Method 1
an acidic aqueous composition with a pH between 0.3 and 3.5 containing complex fluorides of the elements boron, silicon, titanium, zirconium or hafnium individually or in a mixture with one another in total concentrations of the fluoro-anions of between 100 and 4000 ppm as vibratory finishing medium
Implementation Method 2
The workpieces are brought into sliding contact with natural (pebbles, dolomite, quartz, etc.) or synthetic (ceramic or plastic-bound corundum, aluminum oxide, silicon carbide or boron carbide) abrasives
Data Source
AI summary
The invention relates to a method for the vibratory grinding and adhesion-promoting passivating of metal components, which at least partially comprise metals and/or alloys selected from aluminum, magnesium and/or zinc, in one operation employing an aqueous composition having a pH value between 0.3 and 3.5, containing complex fluorides of the elements of boron, silicon, titanium, zircon or hafnium individually or mixed together in concentrations of the fluoro anions of between 100 and 4000 ppm in total as a vibratory grinding medium, and to a component produced directly using this method, and to the use thereof for structural adhesion or for applying other corrosion-protecting coatings. The present invention further relates to the use of a concentrate in order to produce the vibratory grinding medium in the method according to the invention.