Chromium-Free Anodized Metal Surface Sealing
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Solution Overview
Problem
Traditional anodizing processes using chromic acid generate hazardous waste and require alternative surface treatments to enhance corrosion protection on anodized metal surfaces, as chromic acid is being phased out due to environmental regulations.
Innovation Solution
Applying polynuclear clusters comprising aluminum oxide hydroxide to the anodized metal surface, which are synthesized through controlled neutralization of aluminum salts and applied using liquid coating compositions, to seal pores and enhance corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromic acid anodizing is used to form anodized surfaces, then corrosion protection and surface hardness are improved, but hazardous waste generation and environmental harm worsen
Solution Approach 1:
The patent extracts and removes chromium-containing substances from the anodizing process entirely. The invention uses alternative electrolytes (sulfuric acid, oxalic acid, phosphoric acid, or tartaric acid) that do not contain chromium, thereby eliminating the source of hexavalent chromium waste while still forming protective anodized surfaces on aluminum alloys.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte from chromic acid-based to chromium-free alternatives. By modifying the electrolyte chemistry while adjusting other parameters (temperature, voltage, time), the process maintains effective corrosion protection without generating hazardous chromium waste.
2Reliability
If chromic acid anodizing is used to enhance surface protection, then corrosion resistance is improved, but environmental compliance and safety worsen
Solution Approach 1:
The patent removes chromium-based chemicals from the anodizing process, extracting the harmful element while preserving the protective function through alternative electrolyte compositions that meet environmental regulations.
Solution Approach 2:
The patent converts the environmental harm caused by chromic acid into a benefit by developing chromium-free processes that not only eliminate pollution but also provide equivalent or superior corrosion protection, turning a regulatory liability into a competitive advantage.
3Reliability
If traditional sealing methods using sodium dichromate or potassium dichromate are used, then corrosion protection is improved, but hazardous chemical usage and waste generation worsen
Solution Approach 1:
The patent extracts dichromate chemicals from the sealing process and replaces them with chromium-free sealing compositions, eliminating the source of hazardous chromium waste while maintaining pore sealing effectiveness for corrosion protection.
Solution Approach 2:
The patent changes the chemical composition of sealing agents from dichromate-based to alternative compositions that achieve effective pore sealing without chromium, modifying the chemical parameters while maintaining the functional outcome.
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 application of polynuclear aluminum oxide hydroxide clusters effectively seals anodized surfaces, providing enhanced corrosion protection and meeting stringent salt fog test performance requirements without using chromic acid, thus addressing environmental concerns.
Implementation Method 1
Anodizing is used to electrolytically modify metal surfaces of commercial products
Implementation Method 2
a metal article is connected as an anode of an electrolytic circuit in an electrolyte bath to form a layer or region of metal oxide at the surface of the metal article
Implementation Method 3
applying polynuclear clusters comprising aluminum oxide hydroxide to the anodized metal surface
Data Source
AI summary
A method is disclosed for treating an anodized metal surface. According to the method, polynuclear clusters comprising aluminum oxide hydroxide are applied to the anodized metal surface.