Black Passivation Composition for Galvanized Steel
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Solution Overview
Problem
Current black passivation methods for galvanized surfaces lack effective corrosion resistance and adhesion promoter properties, often requiring toxic metals or additional coatings to ensure proper adhesion and uniformity, which can be damaged during installation, leading to visible defects and increased costs.
Innovation Solution
A composition comprising iron compounds, phosphorus-containing compounds, and further transition metal compounds, specifically from scandium, yttrium, and lanthanoids, is used to create a black passivation layer with improved corrosion resistance and excellent adhesion promoter properties, free from cobalt, nickel, and chromium (VI), allowing for uniform and durable coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional black passivation methods are used on galvanized surfaces, then a dark coating is achieved, but the corrosion resistance is insufficient and adhesion promoter properties are lacking
Solution Approach 1:
The patent changes the chemical composition parameters of the passivation solution by incorporating specific transition metal compounds (vanadium, chromium, manganese, molybdenum, tungsten, titanium) in controlled concentrations, along with phosphoric acid and hydrogen peroxide, to transform the passivation layer's properties and achieve both black coloration and enhanced corrosion resistance
Solution Approach 2:
The patent creates a composite passivation layer containing multiple metal compounds (Fe, V, Cr, Mn, Mo, W, Ti) combined with phosphate and oxide components, forming a multi-element conversion coating that provides synergistic effects for both aesthetic appearance and corrosion protection
2Manufacturing precision
If additional coatings are applied to ensure adhesion and uniformity, then coating quality improves, but the process complexity and cost increase
Solution Approach 1:
The patent develops a single passivation solution that simultaneously achieves multiple functions: black coloration, corrosion protection, adhesion promotion, and coating uniformity, eliminating the need for separate treatment steps for each function
Solution Approach 2:
The patent combines multiple beneficial functions (aesthetic appearance, corrosion resistance, adhesion, and uniformity) into one integrated passivation treatment process, merging what would traditionally require multiple separate coatings or treatments
3Illumination intensity
If conventional passivation layers are applied, then a dark appearance is achieved, but the layers are damaged during installation, leading to visible defects
Solution Approach 1:
The patent modifies the passivation layer's mechanical properties by incorporating specific transition metal compounds and controlling the chemical composition ratios, transforming the layer's hardness and mechanical strength to withstand installation stresses while maintaining its dark aesthetic appearance
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 a corrosion-resistant and visually appealing black passivation layer with enhanced adhesion promoter properties, enabling problem-free subsequent coatings and maintaining a uniform appearance even after mechanical damage, thus reducing costs and improving durability.
Implementation Method 1
a composition for passivation, in particular black passivation, of galvanized or zinc-coated surfaces... comprising (a) at least one iron compound, (b) at least one phosphorus-containing compound, and (c) at least one further transition metal compound
Implementation Method 2
zinc and zinc alloys corrode rapidly under oxidative conditions. This deteriorates the appearance of the coatings due to the formation of zinc oxide... To increase the corrosion resistance of components coated with metallic zinc or zinc alloys, the galvanized components are usually subjected to a conversion treatment or passivation
Data Source
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AI summary
The present invention relates to a composition and a method for passivation, in particular black passivation, of galvanized or zinc-containing coatings.