Chromium-Free Coating Thickness Detection Using X-Ray Fluorescence
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Solution Overview
Problem
Current methods for detecting chromium-free coating film thickness on strip steel are inadequate, particularly for on-line monitoring, as they require characteristic elements like chromium, limiting their applicability and precision, and are not suitable for mass production with varying coating film compositions.
Innovation Solution
Incorporating weak characteristic elements such as β-sodium glycerol-phosphate, calcium acetate, titaniumocene complexes, or barium chloride into the chromium-free coating liquid to enable on-line detection using X-ray or gamma rays, allowing for continuous monitoring and correction of film thickness without affecting adhesion, corrosion resistance, or environmental performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If characteristic elements like chromium are used in coating liquid for on-line detection, then detection precision is improved, but the coating film loses environmental compatibility and adhesion performance
Solution Approach 1:
The patent introduces a mediator substance containing a characteristic element that does not become part of the coating film itself but is detectable by X-ray fluorescence. This mediator allows on-line detection without requiring the coating film to contain chromium or other harmful characteristic elements, thus resolving the contradiction between detection precision and environmental compatibility.
2Adaptability or versatility
If multiple sets of thickness detection instruments are equipped for different coating types, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent develops a universal detection method based on X-ray fluorescence that can detect various coating types by simply changing the mediator substance added to the coating liquid. This single detection system can handle multiple coating types without requiring multiple specialized instruments, thus improving adaptability while reducing device complexity.
3Measurement precision
If off-line detection methods are used for coating thickness measurement, then measurement precision is improved through multiple point sampling, but productivity decreases due to inability for on-line monitoring
Solution Approach 1:
The patent replaces the mechanical sampling and manual measurement process of off-line detection with an automated on-line X-ray fluorescence detection system. The mediator substance enables continuous real-time monitoring during coating application, eliminating the need for physical sample extraction and multiple point measurements, thus improving both precision and productivity.
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
Enables precise, on-line detection and optimization of chromium-free coating film thickness across different types, ensuring consistent film properties and reducing errors in mass production, while maintaining the coating's performance and environmental compatibility.
Implementation Method 1
using χ ray or γ ray emitted by an off-line film thickness instrument to excite the two chemical substance so as to obtain characteristic spectrums
Implementation Method 2
using a ray emitted by an on-line coating film thickness instrument to excite the additive and to obtain film thickness
Data Source
Figure 1
AI summary
This invention relates generally to measurement of coating film thickness on surface of strip steel, and particularly, to a measuring method of chromium-free coating film thickness on surface of strip steel which comprises the following steps: selecting two water-soluble chemical substances containing elements P, Ca, Ti, Ba or Sr and not reacting with a chromium-free coating liquid; adding the two water-soluble chemical substances selected in 1) into the chromium-free coating liquid and agitating the them to be homogeneous, thereafter, fabricating a reference sample of coating film; using a ray emitted by an off-line film thickness instrument to excite the two water-soluble chemical substances so as to obtain characteristic spectrums to obtain a correction function expression between the measured film thickness and the thickness correction value by fitting; adding the water-soluble chemical substance which has a weak characteristic spectrum into a chromium-free coating liquid, and using the correction function expression to obtain the actual coating film thickness. By means of on-line detection, the invention is capable to monitor film thickness effectively and optimize the coating process continuously; with high precision, and with no adverse effect on adhesiveness, corrosion-proof and environmental performance of the coating film.