Sol-Gel Coating Composition for Corrosion Protection Without Blistering
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Solution Overview
Problem
Existing sol-gel films used on aircraft surfaces suffer from porosity issues that lead to water retention, osmotic pressure buildup, and corrosion, while traditional corrosion inhibitors reduce adhesive properties and cause blistering.
Innovation Solution
A sol-gel coating system is developed using a corrosion inhibitor salt with thiol moieties, formed by reacting the inhibitor with a hydroxide to create a soluble salt, applied with a controlled pH and molar ratio, combined with organosilane and metal alkoxide to form a corrosion-resistant and adhesive film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If corrosion inhibitors are dispersed within the sol-gel network, then corrosion protection is provided, but osmotic blistering occurs and adhesive properties are reduced
Solution Approach 1:
The patent changes the physical-chemical state of the corrosion inhibitor from insoluble particulate form to soluble salt form. By converting the corrosion inhibitor into a soluble salt, it becomes uniformly distributed within the sol-gel network rather than existing as insoluble particles, thereby eliminating osmotic blistering while maintaining corrosion protection and adhesive properties
Solution Approach 2:
The patent creates a dense, non-porous sol-gel film structure by controlling the sol-gel process parameters. This dense structure prevents water accumulation and eliminates the porous pathways that would allow osmotic pressure buildup, thereby preventing blistering while maintaining corrosion inhibition
2Strength
If adhesive sol-gel film is disposed between metal and primer, then adhesion is promoted, but pores form that retain water and promote corrosion
Solution Approach 1:
The patent modifies the sol-gel formulation parameters including pH control, molar ratios of reactants, and addition of chelating agents to achieve optimal crosslinking density. These parameter changes result in a film that is sufficiently dense to prevent water retention while maintaining the adhesive functionality required for bonding metal to primer
Solution Approach 2:
The patent creates a composite sol-gel system incorporating multiple functional components: adhesion promoters for metal bonding, corrosion inhibitors in soluble salt form, and crosslinking agents for network formation. This composite approach achieves simultaneous adhesion, corrosion protection, and water resistance without the drawbacks of previous single-function systems
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 system prevents water accumulation, reduces blistering, and maintains adhesive properties, providing effective corrosion protection for metal surfaces without disrupting the sol-gel network.
Implementation Method 1
formed by reacting the inhibitor with a hydroxide to create a soluble salt
Implementation Method 2
The system prevents water accumulation
Implementation Method 3
the presence of water within the pores is subject to an increase of osmotic pressure within the pore which creates a visually noticeable defect in the aircraft surface known as a 'blister'
Data Source
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AI summary
Aspects described herein generally relate to a method of coating a metallic surface. The method includes forming a solution including a corrosion inhibitor having one or more thiol moieties and a hydroxide. The metallic surface is coated with the solution to form a treated metallic surface. The treated metallic surface is further coated with an organosilane, an acid, and a metal alkoxide to form a coating system.