Silver Coating Abrasion Resistance via Columnar Crystal Structure
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Solution Overview
Problem
Silver plating in connectors and switches wears away quickly due to repeated switching operations, leading to increased contact resistance, and attempts to enhance abrasion resistance by increasing plating thickness or adding hardening agents have been unsuccessful, with the latter making the coating more brittle.
Innovation Solution
A silver-coated material with a columnar structured silver or silver alloy outermost layer, formed by plating and heat-treating at specific temperatures and times, resulting in improved abrasion resistance and maintaining low contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of silver plating is increased to prevent wear, then the abrasion resistance is improved, but the cost increases and the plating becomes more prone to brittleness
Solution Approach 1:
The invention changes the crystal grain size parameter of the silver plating from conventional larger grains to specifically 0.5 μm or less, and controls the crystal structure to be oriented. This parameter change allows achieving excellent abrasion resistance with thinner plating, resolving the contradiction between abrasion resistance and material quantity.
Solution Approach 2:
The invention creates a composite structure within the silver plating layer by forming specific crystal grain structures (oriented crystals with 0.5 μm or less grain size) combined with controlled oxide content (0.1-10 at%). This internal composite structure provides both wear resistance and electrical conductivity without requiring increased thickness.
2Strength
If hardening agents such as antimony are added to increase coating hardness, then the abrasion resistance is improved, but the coating becomes more brittle and abrasion resistance deteriorates
Solution Approach 1:
Instead of adding hardening agents, the invention changes the physical structure parameters of the silver plating by controlling crystal grain size to 0.5 μm or less and creating oriented crystal structures. This structural parameter change provides hardness and wear resistance without introducing brittleness from chemical additives.
Solution Approach 2:
The invention copies the successful crystal structure characteristics from materials known for wear resistance and applies them to silver plating by controlling nucleation and growth conditions during electroplating, achieving similar wear resistance properties without using hardening agent additives.
3Ease of operation
If repeated switching operations are performed, then the switch functionality is maintained, but the silver plating wears away and contact resistance rises
Solution Approach 1:
The invention performs preliminary action by controlling the crystal structure and oxide content during the plating process itself, creating a pre-optimized structure that resists wear and maintains electrical properties. This preliminary structural preparation prevents degradation during subsequent repeated switching operations.
Solution Approach 2:
The invention changes the chemical composition parameters by controlling oxide content to 0.1-10 at% in specific ranges, which creates a surface structure that is more resistant to wear during switching operations while maintaining electrical conductivity, thus preventing contact resistance rise.
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 silver-coated material exhibits excellent abrasion resistance with minimal coating loss and low contact resistance even after extended use, suitable for repeated switching operations without surface wear or increased resistance.
Implementation Method 1
a layer made of at least silver or a silver alloy is formed by plating
Implementation Method 2
heat-treating under specific heating conditions
Implementation Method 3
crystals of a columnar structure having an average crystal grain size of 0.2 μm or more and 0.5 μm or less
Data Source
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AI summary
The object of this invention is to provide a silver-coated material of excellent abrasion resistance in which, even when used as, for example, a moving contact and/or a fixed contact in a switch used over an extended period of time under conditions where switching is repeatedly carried out, the silver or silver alloy layer at the surface does not wear away and, moreover, the contact resistance does not rise. A silver-coated material having, as an outermost layer on an electrically conductive base material, a layer made of at least silver or a silver alloy, this silver-coated material having a coating loss, in an abrasion resistance test, of less than 40 mg and having an initial contact resistance of less than 10 mΩ and a contact resistance of less than 10 mΩ after a sliding wear test carried out under certain conditions.