Aluminum Alloy Sheet Homogenization for Streak-Free Anodizing
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Solution Overview
Problem
Aluminum alloy sheets often exhibit a band-like streak pattern after anodizing, which is not effectively prevented by existing methods controlling chemical components, crystal grain size, or precipitate distribution.
Innovation Solution
Homogenizing an ingot with specific elements like Ti and Cr at temperatures above the solidus temperature for extended periods, followed by point analysis and hot/cold rolling to achieve a controlled concentration of peritectic elements, resulting in an aluminum alloy sheet with a band-like concentration variation of peritectic elements that suppresses streak patterns during anodizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional homogenization methods are used (500-610°C for 1 hour or more), then the ingot is sufficiently homogenized, but band-like streak patterns still appear after anodizing
Solution Approach 1:
The patent changes the homogenization parameters by extending the time to 3 hours or more and adjusting the temperature to be at or above the solidus temperature, which fundamentally alters the diffusion kinetics and achieves uniform peritectic element distribution that prevents streak patterns during anodizing
Solution Approach 2:
The patent performs preliminary homogenization treatment before hot rolling to ensure uniform distribution of peritectic elements in the ingot, which prevents the formation of band-like streak patterns during subsequent anodizing processes
2Stability of the object's composition
If homogenization time is extended to 3 hours or more at solidus temperature or higher, then uniform peritectic element distribution is achieved, but production time and energy consumption increase
Solution Approach 1:
By changing the temperature parameter to be at or above the solidus temperature, the patent accelerates the homogenization kinetics, allowing uniform distribution to be achieved in 3 hours or more rather than requiring excessively longer times at lower temperatures
Solution Approach 2:
The patent utilizes the phase transition characteristics near the solidus temperature to enhance diffusion rates, where the material is in a semi-molten state that facilitates rapid and uniform redistribution of peritectic elements throughout the ingot
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 method produces an aluminum alloy sheet with excellent surface quality after anodizing, free from band-like streak patterns, by maintaining a concentration difference of peritectic elements within specific limits, ensuring a uniform anodic oxide coating and improved strength.
Implementation Method 1
an element that undergoes a peritectic reaction with aluminum and is present in a solid-solution state
Implementation Method 2
measures the concentration of the peritectic element from fluorescent X-rays that are generated by applying electron beams using an EPMA
Implementation Method 3
an aluminum alloy sheet that exhibits excellent surface quality after anodizing
Data Source
AI summary
An aluminum alloy sheet that exhibits excellent surface quality after anodizing, includes a peritectic element that undergoes a peritectic reaction with at least aluminum, and requires an anodic oxide coating is characterized in that the concentration of the peritectic element in a solid-solution state that is present in the outermost surface area of the aluminum alloy sheet varies in the widthwise direction of the aluminum alloy sheet in the form of a band having a width of 0.05 mm or less, and the difference in the concentration of the peritectic element between adjacent bands is 0.008 mass% or less.