Ag-In Alloy Surface Layer for Low Friction Connection Terminals
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Solution Overview
Problem
Existing metallic materials with Ag layers on connection terminals have high friction coefficients, leading to increased force requirements for insertion and removal, and do not effectively reduce contact resistance and friction simultaneously, especially in high-temperature environments.
Innovation Solution
A metallic material with a surface layer containing Ag and In, where In is present in a lower atomic ratio than Ag, forming an Ag—In alloy with a high-concentration In portion, which reduces friction coefficient while maintaining low contact resistance, and an intermediate layer such as Ni is used to prevent diffusion and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an Ag layer is provided on the surface of a connection terminal, then high electric conductivity and heat resistance are achieved, but the friction coefficient becomes high
Solution Approach 1:
The patent applies composite materials by creating a surface layer that is a composite of Ag and In metals. The Ag provides high electric conductivity and heat resistance, while the In provides low friction coefficient. This composite structure allows both functions to coexist on the surface without requiring separate layers, resolving the contradiction between electrical performance and friction characteristics.
Solution Approach 2:
The patent applies local quality by creating specific regions within the surface layer with different Ag-In compositions. The surface layer contains both an Ag-rich region (for conductivity) and an In-rich region (for low friction), allowing different local areas to fulfill different functional requirements simultaneously.
2Ease of operation
If a hard metallic layer is provided on the lower surface of the Ag layer to reduce friction coefficient, then friction is reduced, but the alloy layer does not directly affect surface characteristics
Solution Approach 1:
Instead of placing the friction-reducing layer beneath the Ag layer (as in conventional approaches), the patent inverts the structure by making the Ag-In composite layer itself the surface layer that directly contacts the opposite member. This allows the low-friction In component to be directly exposed and functional, while the Ag component maintains conductivity, resolving the issue of the alloy layer being hidden and ineffective.
3Ease of operation
If In content is increased to reduce friction coefficient, then friction is reduced, but oxidation resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the In content within a specific range (0.1-10 at%, preferably 0.5-5 at%). This controlled parameter adjustment ensures sufficient In is present to provide low friction through solid lubrication, while keeping the concentration low enough to maintain oxidation resistance and preserve the dominant Ag character of the surface layer.
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 surface layer achieves both low contact resistance and friction coefficient, maintaining stability even at high temperatures by utilizing Ag's conductivity and In's solid lubricating properties, while minimizing oxidation effects.
Implementation Method 1
Ag has high electric conductivity and a high melting point, is relatively less subject to oxidizing
Implementation Method 2
In is a soft metal and exhibits a solid lubricating action, the friction coefficient of the surface of the metallic material can be kept down
Implementation Method 3
an intermediate layer containing at least one kind selected from the group consisting of Ni, Cr, Mn, Fe, Co, and Cu
Data Source
AI summary
A metallic material that includes a base material; and a surface layer formed on a surface of the base material and exposed on an outermost surface, wherein the surface layer contains Ag, and In less than the Ag in atomic ratio, and a connection terminal being made of the metallic material, wherein the surface layer is formed on a surface of the base material, at least in a contact portion electrically contacting an opposite electrically conductive member.