Slide Member Bi Overlay Ag Intermediate Layer Diffusion Control

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Solution Overview

Problem

Bi-based overlays in slide members face issues with conformability due to diffusion of additive elements into the intermediate layer at high temperatures, reducing their effectiveness in mating with shafts.

Innovation Solution

A laminate structure with a Bi or Bi-based alloy overlay and an Ag or Ag-based alloy intermediate layer, where the additive element is present in a low melting point metal, with its quantity in the intermediate layer being five times or more than in the overlay, suppresses diffusion and maintains conformability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If Bi-based alloy is used as overlay to replace Pb-based alloy, then environmental pollution is reduced, but conformability deteriorates due to hardness of Bi

Engineering Contradiction:

Improveenvironmental pollutionVSAvoidconformability

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent changes the chemical composition parameters of the overlay by adding specific elements (Sn, In, or Ga) to the Bi-based alloy. This modifies the physical properties of the overlay, specifically reducing its hardness and improving conformability while maintaining the environmental benefits of using Bi instead of Pb.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by combining Bi with additive elements (Sn, In, or Ga) in specific proportions. This composite structure leverages the low melting point and softness of the additive elements to improve the overall conformability of the Bi-based overlay, while the intermediate layer composed of Ag or Ag-based alloy with specific additive elements further enhances the composite structure's performance.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If additive elements are added to Bi-based overlay to improve conformability, then conformability improves, but diffusion of additive elements into intermediate layer occurs at high temperature, reducing conformability

Engineering Contradiction:

ImproveconformabilityVSAvoidcomposition stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent introduces an intermediate layer composed of Ag or Ag-based alloy with specific additive elements (Sn, In, or Ga) that act as a barrier between the Bi-based overlay and the base material. This intermediate layer prevents the diffusion of additive elements from the overlay into the base material at high temperatures, thereby maintaining the composition stability and conformability of the overlay during service.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent optimizes the concentration parameters of additive elements in both the overlay and intermediate layer. By carefully controlling the amounts of Sn, In, or Ga in each layer, the patent creates a concentration gradient that thermodynamically suppresses diffusion while maintaining the desired conformability of the overlay.

Inventive Principle:

Principle #35Parameter changes

3Strength

If Ag or Ag-based alloy is used as intermediate layer with Bi-based overlay, then bonding is improved, but diffusion of additive elements into intermediate layer occurs at high temperature

Engineering Contradiction:

Improvebonding strengthVSAvoidadditive element diffusion

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the compositional parameters of the Ag-based intermediate layer by adding specific amounts of additive elements (Sn, In, or Ga). This creates a concentration gradient that suppresses diffusion while maintaining good bonding properties. The specific composition ranges are optimized to balance bonding strength and diffusion resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite intermediate layer structure by combining Ag with additive elements in specific proportions. This composite structure provides both excellent bonding to the Bi-based overlay and resistance to diffusion of additive elements, effectively addressing both requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

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

This configuration prevents the diffusion of additive elements into the intermediate layer, maintaining the conformability and fatigue resistance of the overlay over time, even under high load usage.

Implementation Method 1

the additive elements within the overlay occasionally diffuse into the intermediate layer to disadvantageously reduce the conformability of the overlay

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS8216692B2Slide member

Publication Date: 2012.07.10 DAIDO METAL CO LTD

AI summary

A slide member including a base material; an intermediate layer consisting of Ag or Ag-based alloy and an additive element of a first quantity formed over the base material; and an overlay comprising Bi or Bi-based alloy and the additive element of a second quantity formed over the intermediate layer, wherein the additive element consists of a low melting point metal, the first quantity being five times or greater than the second quantity.