Sealing Process for Anodized Aluminum Alloy Surfaces
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Solution Overview
Problem
Anodized aluminum layers with porous structures are vulnerable to corrosion due to exposure to corrosive environments, and existing corrosion barriers like hexavalent chromium pose regulatory concerns.
Innovation Solution
A sealing process involving the application of trivalent chromium and rare earth element precursors, along with an alkaline earth element precursor, to form a physical barrier within the porous structure of anodized aluminum alloys, creating reservoirs of trivalent chromium and a crystalline structure that enhances corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hexavalent chromium is used as a corrosion barrier, then corrosion protection is improved, but regulatory compliance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter from hexavalent chromium to trivalent chromium, maintaining corrosion protection functionality while eliminating regulatory compliance issues. This substitution of chemical parameters resolves the contradiction between effective corrosion barrier performance and regulatory acceptance.
Solution Approach 2:
The patent creates a composite sealing structure combining multiple materials (trivalent chromium compounds, rare earth elements, alkaline earth elements) within the porous anodized layer. This composite approach achieves superior corrosion protection while using environmentally compliant materials, simultaneously improving reliability and regulatory compliance.
2Area of stationary object
If the anodized layer remains porous, then surface area is increased, but corrosion resistance deteriorates
Solution Approach 1:
The patent applies different properties to different regions: the outer surface maintains the porous anodized structure for surface area and aesthetics, while the interior pores are filled with sealing compounds (trivalent chromium, rare earth elements) to provide corrosion resistance. This local differentiation resolves the contradiction between surface area and corrosion resistance.
Solution Approach 2:
The patent nests sealing compounds within the porous structure of the anodized layer. The porous anodized layer provides the outer framework with high surface area, while the trivalent chromium and rare earth element compounds are nested within the pores to provide corrosion protection, creating a hierarchical structure that satisfies both requirements.
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 process effectively seals the anodized layer, reducing corrosion risk and avoiding the regulatory issues associated with hexavalent chromium by forming a dense, stable physical barrier that inhibits corrosion within the porous structure.
Implementation Method 1
applying a first reactant to a substrate having a porous structure, the first reactant comprising at least one of a trivalent chromium precursor and a transition metal precursor; and applying a second reactant to the first reactant... to form reservoirs of trivalent chromium in the porous structure, and a physical barrier over the substrate and the reservoirs
Implementation Method 2
the physical barrier comprises a doped perovskite or pyrochlore crystalline structure... the reactants react to form a compound with the composition RECrO3... or La2Zr2O7 that crystallizes into a pyrochlore crystal structure
Data Source
AI summary
A sealing process includes applying a first reactant to a substrate having a porous structure, the first reactant comprising a chromium (III) precursor and a transition metal precursor and applying a second reactant to the first reactant, the second reactant comprising a rare earth element precursor and an alkaline earth element precursor to form reservoirs of trivalent chromium in pore space of the porous structure, and a physical barrier over the substrate and the reservoirs.