Stainless Steel Passivation Film for Metal Plating Adhesion
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Solution Overview
Problem
Conventional metal plate coated stainless materials face issues with thin gold plated layers leading to reduced coverage and adhesion, causing corrosion and increased costs due to thick layers, and existing solutions either compromise on thickness or incur high costs.
Innovation Solution
A method involving the formation of a passivation film on a stainless steel sheet with specific Cr/O and Cr/Fe values, followed by a metal plating process using Ag, Pd, Pt, Rh, Ru, Cu, Sn, or Cr, ensuring high coverage and adhesion even with reduced thickness, thereby enhancing corrosion resistance and conductivity while being cost-effective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the thickness of the metal plated layer is reduced to lower cost, then cost decreases, but coverage and interfacial adhesion property deteriorate
Solution Approach 1:
A passivation film is formed on the stainless steel sheet surface before applying the metal plated layer. This preliminary treatment creates an optimized surface state that enhances adhesion of the metal plated layer, allowing use of thinner plated layers without compromising interfacial adhesion property
Solution Approach 2:
The surface properties of the stainless steel sheet are modified by controlling the passivation film formation through specific immersion conditions (sulfuric acid concentration, temperature, time). This changes the surface chemistry to optimize metal plated layer adhesion, enabling reduced plated layer thickness while maintaining reliability
2Reliability
If the thickness of the metal plated layer is increased to improve coverage and adhesion, then interfacial adhesion property improves, but cost increases
Solution Approach 1:
The passivation film is formed as a preparatory step that creates an ideal surface for metal plated layer deposition. This preliminary surface treatment enhances the bonding strength between the substrate and the metal plated layer, allowing achievement of high interfacial adhesion with reduced metal plated layer thickness, thereby lowering material cost
3Reliability
If underlying nickel plating is performed to improve interfacial adhesion, then interfacial adhesion property improves, but nickel dissolution causes delamination when defects occur
Solution Approach 1:
The intermediate nickel plated layer is completely removed from the structure. Instead, a passivation film is formed directly on the stainless steel sheet surface, which provides adequate adhesion for the metal plated layer without the harmful nickel dissolution issue. This extracts the problematic intermediate layer while maintaining the essential adhesion function
Solution Approach 2:
The passivation film serves as a thin, functional intermediate layer that performs the adhesion function temporarily and effectively. It is not a permanent thick layer like nickel plating but provides sufficient bonding support during service, eliminating the nickel dissolution problem while maintaining interfacial adhesion property
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 achieves excellent corrosion resistance and electrical conductivity with improved adhesion and reduced material thickness, making the metal plate coated stainless material suitable for applications like connectors and fuel cells while being cost-effective.
Implementation Method 1
a passivation film formed thereon, the passivation film having a Cr/O value in the range of 0.05 to 0.2 and a Cr/Fe value in the range of 0.5 to 0.8 at the surface
Implementation Method 2
a metal plated layer formed from any one metal selected from among Ag, Pd, Pt, Rh, Ru, Cu, Sn and Cr, or at least two or more metals selected from among these
Data Source
AI summary
There is provided a metal plate coated stainless material (100) which includes a stainless steel sheet (10) having formed thereon a passivation film (11) having a Cr/O value in the range of 0.05 to 0.2 and a Cr/Fe value in the range of 0.5 to 0.8 at the surface as measured by an Auger electron spectroscopy analysis and a metal plated layer (20) formed on the passivation film (11) of the stainless steel sheet (10), in which the metal plated layer (20) is a plated layer formed from any one metal selected from among Ag, Pd, Pt, Rh, Ru, Cu, Sn and Cr, or an alloy of these metals.