Colorimetry for Chromium III Conversion Layer Verification
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Solution Overview
Problem
The detection of thin chemical conversion layers obtained using chromium at the +III oxidation state on aluminum substrates is challenging due to their similarity in appearance to the substrate and other coatings, leading to extended inspection times and potential additional treatments.
Innovation Solution
A method involving a colorimeter to measure and compare the color of the chemical conversion layer with a reference color, using a treatment solution like SurTec® 650, to quickly and non-destructively verify the presence and correctness of the conversion layer, facilitating rapid detection and avoiding unnecessary treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical conversion treatment with chromium +III is used to treat aluminum substrate, then the coating meets REACh regulation requirements and provides corrosion protection, but the coating becomes very close in appearance to the substrate making detection difficult
Solution Approach 1:
The patent applies colorimetry to detect the chemical conversion layer by measuring color parameters (L*, a*, b*) of the coated surface. The method establishes reference color values for properly treated surfaces and compares them with tested surfaces to verify treatment effectiveness, solving the detection difficulty caused by visual similarity between the chromium +III coating and the substrate
Solution Approach 2:
The patent replaces complex detection methods (such as X-ray spectroscopy mentioned in WO-A-2007/134152) with a simple colorimetric measurement system. This substitution uses optical measurement instead of sophisticated analytical instruments, making the detection process quick, simple, and suitable for routine inspection while maintaining reliability
2Measurement precision
If standard detection technologies are used to detect thin chemical conversion coatings, then the detection process becomes complex and time-consuming, but the coatings are too thin to be easily detected
Solution Approach 1:
The patent uses colorimetric measurement to detect thin chemical conversion coatings (less than a few hundred nanometers) by measuring color parameters rather than relying on thickness-based detection. This approach provides sufficient measurement precision for thin coatings while maintaining rapid inspection speed, avoiding the time loss associated with complex detection technologies
3Ease of manufacture
If retouching operations with chromium +III are performed on previously treated parts, then the treatment can be applied locally, but the retouching becomes indistinguishable from surrounding coatings
Solution Approach 1:
The patent applies colorimetry to detect retouching operations by measuring color parameters of the retouched area and comparing them with reference values. This allows local retouching with chromium +III to be performed and subsequently verified, solving the problem of making retouching indistinguishable from surrounding coatings while maintaining ease of manufacture
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
This method allows for reliable and rapid verification of the chemical conversion treatment, differentiating between similar surfaces and confirming the treatment's correctness, thus accelerating the processing and simplifying the treatment of parts.
Implementation Method 1
checking the presence of the chemical conversion layer obtained during step a) by measuring, using a colorimeter, the color of said chemical conversion layer
Data Source
Figure 1~2
AI summary
The invention relates to a method for manufacturing and monitoring a part (1). The method comprises the following steps: a) treating a substrate comprising aluminum by means of a chemical conversion method using a treatment solution comprising chromium at oxidation degree +III such as to obtain a part (1) having a chemical conversion layer (3); and b) monitoring the presence of the chemical conversion layer (3) obtained during Step a) by measuring, through the use of colorimetry, the color of said chemical conversion layer (3) and comparing said measured color with a reference color.