Concentrated Sol-Gel Coating for Metal Corrosion Resistance
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Solution Overview
Problem
Existing sol-gel coating processes for metal surfaces face challenges such as high solvent content, complex implementation, and inadequate corrosion resistance, leading to environmental concerns and reduced productivity.
Innovation Solution
A concentrated sol-gel coating solution with increased concentrations of organometallic compounds, organosilanes, and catalysts, exceeding 30% total weight, is used to achieve a high dry thickness in a single layer, enhancing corrosion resistance without additional organic solvents, and allowing for simpler, more efficient application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wet-chemical processes (anodizing, chromatizing) are used to treat metal surfaces, then corrosion resistance and adhesion properties are improved, but environmental harm and waste generation increase due to use of strong acids, bases, and toxic materials
Solution Approach 1:
The patent changes the chemical composition parameters by replacing toxic wet-chemical reagents with environmentally benign sol-gel precursors. The sol contains metal alkoxides and organosilanes that hydrolyze to form protective coatings without requiring strong acids, bases, or chromates, thus maintaining corrosion resistance while eliminating environmental harm.
Solution Approach 2:
The sol-gel process uses disposable, non-toxic precursor solutions that can be applied and then rinsed with water without generating hazardous waste. The coating forms in situ from these temporary precursor solutions, eliminating the need for toxic bath solutions that require expensive treatment and disposal.
2Strength
If conventional sol-gel processes with low solids content (3-5%) are used, then adhesion is maintained, but coating thickness is insufficient and requires multiple applications reducing productivity
Solution Approach 1:
The patent changes the concentration parameter by formulating a sol with high solids content (greater than 30%), which allows deposition of thick coatings in a single application. The high concentration of metal alkoxide and organosilane precursors enables formation of a sufficiently thick dry coating (several micrometers) without requiring multiple dips or prolonged treatment times, thus improving productivity while maintaining adhesion.
3Manufacturing precision
If conventional sol-gel sols with low solids content are used, then multiple applications are required to achieve sufficient thickness, but this increases process complexity and treatment time
Solution Approach 1:
The patent changes the solids content parameter to greater than 30%, which allows a single dip-coating operation to deposit a sufficiently thick layer (several micrometers dry thickness). This eliminates the need for multiple applications or complex multi-step processes, simplifying the overall manufacturing process while maintaining precise thickness control through the sol-gel mechanism.
4Reliability
If concentrated sols are used to reduce number of applications, then coating thickness and corrosion resistance improve, but adhesion may be compromised according to prior art
Solution Approach 1:
The patent uses a composite sol formulation containing both metal alkoxide (for corrosion resistance) and organosilane (for adhesion). The organosilane component specifically targets the metal surface to form a strongly adherent silane layer, while the metal alkoxide provides the corrosion-resistant oxide coating. This composite approach ensures both adhesion and corrosion resistance are achieved simultaneously even at high solids content.
Solution Approach 2:
The patent applies local quality by having different components of the sol perform different functions at different locations. The organosilane preferentially interacts with the metal substrate surface to provide adhesion, while the metal alkoxide forms the protective corrosion-resistant layer on top. This spatial differentiation of functions ensures both adhesion and corrosion resistance are optimized.
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 significant improvements in corrosion protection, adhesion, and thickness uniformity, achieving salt-spray resistance for several hundred hours and maintaining flexibility and adhesion properties, while being environmentally friendly and cost-effective.
Implementation Method 1
sol for the sol-gel coating of a surface... process for sol-gel coating a surface
Implementation Method 2
a)—3% to 30%, preferably 5% to 20%, more preferably 7% to 15%, especially 8% to 14%, more especially 10% to 13%, for example 10.8% or 12%, of at least one organometallic compound of zirconium, aluminium or titanium
Data Source
AI summary
Sol for the sol-gel coating of a surface, said sol comprising, in percent by weight:a)—3% to 30%, preferably 5% to 20%, more preferably 7% to 15%, especially 8% to 14%, more especially 10% to 13%, for example 10.8% or 12%, of at least one organometallic compound of zirconium, aluminium or titanium;b)—5% to 50%, preferably 5% to 40%, more preferably 10% to 40%, especially 15% or 20% to 30%, for example 22% or 23%, of at least one organosilane compound;c)—1% to 15%, preferably 2% to 10%, more preferably 3% to 8%, for example 5%, of at least one compound selected from acids, bases, glycols and ethoxyethanol;d)—the remainder to 100% of demineralized or distilled water;the total amount of a) and b) being greater than 30%, preferably greater than 31.2%; 31.5%; 32%; or 33%, more preferably greater than 35%, especially greater than 40%, more especially greater than 50%.Kit comprising:a first container containing a first part A, in liquid form, comprising components a), c) and d) of the sol;a second container containing a second part B, in liquid form, comprising component b) of the sol.Process for preparing a sol-gel layer employing said sol and layer thus obtained, and substrate coated with at least one such sol-gel layer.Process for preparing a coating comprising two or more layers on a surface of a substrate, at least one of these layers being a sol-gel layer prepared by the process above.