Surface-Treated Steel Coating for White Rust Resistance and Conductivity
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Solution Overview
Problem
Existing surface-treated steels face issues with insufficient initial white rust resistance and poor conductivity, particularly in worked portions, despite having good corrosion resistance and paint adhesiveness.
Innovation Solution
A surface-treated steel with a chemical conversion coating film containing an organosilicon compound, phosphorus (P), and fluorine (F) as inhibitors, with controlled abundance ratios of alkylene groups and siloxane bonds, enhancing the barrier and inhibitor effects without relying on organic resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a chromate-free surface treatment using silane coupling agents is applied, then environmental compatibility and paint adhesiveness are improved, but initial white rust resistance and corrosion resistance in worked portions deteriorate
Solution Approach 1:
The patent uses a composite coating film containing multiple silane coupling agents with different functional groups (amino group, epoxy group, carboxyl group) combined with specific inorganic compounds (titanium compound, zirconium compound, phosphate compound, fluorine compound). This composite structure provides both environmental compatibility and enhanced corrosion resistance including initial white rust resistance.
Solution Approach 2:
The patent specifies precise compositional parameters for the coating film, including the abundance ratio of cyclic siloxane bond to chain siloxane bond (0.4-2.5), and specific content ranges of various inorganic compounds. These parameter optimizations ensure both environmental compatibility and improved corrosion resistance in worked portions.
2Reliability
If organic resins are added to improve film formation and corrosion resistance, then corrosion resistance is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent extracts and eliminates organic resins from the coating film composition, relying solely on inorganic compounds (silane coupling agents, titanium compound, zirconium compound, phosphate compound, fluorine compound) to form the protective film. This removal of organic resins maintains electrical conductivity while achieving sufficient corrosion resistance through the inorganic composite structure.
3Reliability
If the coating film thickness is increased to improve barrier property, then corrosion resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent optimizes the compositional parameters of the coating film, including the abundance ratio of cyclic to chain siloxane bonds (0.4-2.5) and specific content ranges of inorganic compounds, to achieve effective corrosion protection at moderate thickness levels without requiring excessively thick coatings that would increase manufacturing complexity.
Solution Approach 2:
The multi-component inorganic composite structure provides enhanced corrosion resistance through synergistic effects of different compounds, allowing for thinner yet more effective coating films compared to single-component systems, thereby reducing manufacturing complexity and cost.
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 solution provides improved corrosion resistance and conductivity, particularly in both flat and worked portions, by optimizing the chemical conversion coating film composition and manufacturing process.
Implementation Method 1
In addition, in a portion where the chemical conversion coating film is damaged due to defects or the like, corrosion resistance is improved as the effect (inhibitor effect) of preventing corrosion of the plated layer due to elution of a substance (mainly a metal element) in the chemical conversion coating film when moisture adheres is higher.
Implementation Method 2
The corrosion resistance of the surface-treated steel having a chemical conversion coating film is improved as the barrier property (property of blocking permeation of corrosion factors such as moisture and chloride ions) of the chemical conversion coating film is higher.
Implementation Method 3
a chemical conversion coating film formed on a surface of the plated layer, wherein the chemical conversion coating film contains an organosilicon compound having a siloxane bond
Implementation Method 4
the chemical conversion coating film contains an organosilicon compound having a siloxane bond
Data Source
AI summary
The surface-treated steel includes: a steel; a plated layer containing Zn or a Zn alloy formed on a surface of the steel; and a chemical conversion coating film formed on a surface of the plated layer, wherein the chemical conversion coating film contains an organosilicon compound having a siloxane bond, and P and F, and when the abundance ratio of an alkylene group and a siloxane bond in the organosilicon compound is measured by Fourier transform infrared spectroscopy (FT-IR), a ratio A1/A2 of a peak value A1 of an absorbance at 2,800 to 3,000 cm−1 indicating the alkylene group to a peak value A2 of an absorbance at 1,030 to 1,200 cm−1 indicating the siloxane bond is 0.10 to 0.75.