Fibrous Silver Electrical Contacts via Ball Milling and Extrusion

Solution Overview

Problem

Existing methods for preparing silver-based electrical contact materials with fiber-like reinforcing nanoparticles are complex, require specific equipment, and are not suitable for large-scale production due to requirements on processing deformation and ductility of the reinforcing phase.

Innovation Solution

A method involving high energy ball milling of silver and reinforcing phase powders, followed by cold isostatic pressing, sintering, hot pressing, and hot extrusion to achieve a neat fibrous structure without specific requirements on equipment or the plasticity and ductility of the reinforcing phase, allowing for a simple and cost-effective large-scale production process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional powder metallurgy sintering and extrusion method is used, then the process is simple and suitable for large-scale production, but the desired neat fibrous structure cannot be obtained and large reinforcing particles are produced which undermine product performance

Engineering Contradiction:

Improvesuitability for large-scale productionVSAvoidfibrous structure quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention performs preliminary action by pre-mixing the reinforcing phase material powders with base silver powders using high energy ball milling before sintering. This pre-mixing creates a uniform composite powder with fine particle distribution, which then forms the desired fibrous structure during subsequent extrusion, resolving the contradiction between simple processing and high structural quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the particle size parameter through high energy ball milling, reducing the reinforcing phase particles to a fine size range (0.1-10 μm) before sintering. This parameter change enables the formation of neat fibrous structures during extrusion while maintaining process simplicity and suitability for large-scale production

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If modification of conventional method with improved extrusion and increased processing deformation is used, then fibrous structure can be obtained, but the method is not suitable for small deformation cases such as extruding into strips or sheets and is not suitable for reinforcing phase with poor plasticity and ductility

Engineering Contradiction:

Improvefibrous structure qualityVSAvoidapplicability to different deformation conditions and materials

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The invention performs preliminary action by pre-mixing the reinforcing phase material powders with base silver powders using high energy ball milling before sintering. This pre-mixing creates a uniform composite powder with fine particle distribution, which then forms the desired fibrous structure during subsequent extrusion, resolving the contradiction between simple processing and high structural quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the particle size parameter through high energy ball milling, reducing the reinforcing phase particles to a fine size range (0.1-10 μm) before sintering. This parameter change enables the formation of neat fibrous structures during extrusion while maintaining process simplicity and suitability for large-scale production

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If combination of pre-design of green body and extruding method is used, then neat and continuous fibrous structure can be created, but the method is relatively complex, places particular requirement on plasticity and ductility of reinforcing wires, and requires advance preparation of silver-based wires with reinforcing materials

Engineering Contradiction:

Improvefibrous structure qualityVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention performs preliminary action by pre-mixing the reinforcing phase material powders with base silver powders using high energy ball milling before sintering. This pre-mixing creates a uniform composite powder with fine particle distribution, which then forms the desired fibrous structure during subsequent extrusion, resolving the contradiction between simple processing and high structural quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the particle size parameter through high energy ball milling, reducing the reinforcing phase particles to a fine size range (0.1-10 μm) before sintering. This parameter change enables the formation of neat fibrous structures during extrusion while maintaining process simplicity and suitability for large-scale production

Inventive Principle:

Principle #35Parameter changes

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 method results in silver-based electrical contact materials with enhanced resistance to welding and arc erosion, improved conductivity, and suitable processing performance, with a 10-20% increase in arc erosion resistance, 5-20% increase in conductivity, and 10-30% increase in service life compared to materials with ordinary particle dispersion.

Implementation Method 1

placing the mixed powders into a high energy ball milling tank for ball-milling

Methodology Applied

Scientific EffectMechanical activation:

Implementation Method 2

the reinforcing phase material powders and the base silver powders are mixed in such a weight proportion between the reinforcing phase material powders and the base silver powders, that composite powders with silver-coated reinforcing phase material and aggregates thereof are obtained

Methodology Applied

Scientific EffectBall milling:

Implementation Method 3

processing powder body obtained from the step (2) with cold isostatic pressing to obtain a green body

Methodology Applied

Scientific EffectIsostatic pressing:

Implementation Method 4

sintering green body obtained from step (3)

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 5

hot pressing the green body obtained from step (4)

Methodology Applied

Scientific EffectHot pressing:

Implementation Method 6

hot extruding the green body obtained from step (5) to obtain the fibrous silver-based electrical contact material

Methodology Applied

Scientific EffectHot extrusion: Extrusion

Data Source

PatentEP2537949B1Method for preparing fibrous silver-based electrical contact material

Publication Date: 2018.11.28 WENZHOU HONGFENG ELECTRICAL ALLOY

Figure 1~3

AI summary

A method for preparing silver-based electrical contact materials with fiber-like arrangement of reinforcing nanoparticles includes (1) uniformly mixing reinforcement powders and silver matrix powders for ball milling; (2) pouring the obtained composite powders and silver matrix powders into a powder mixing machine for powder mixing; (3) cold isostatic pressing; (4) sintering; (5) hot pressing; and (6) hot extruding to obtain silver-based electrical contact materials with fiber-like arrangement of reinforcing nanoparticles. The method of the present invention can obtain silver-based electrical contact materials with fiber-like arrangement of reinforcing nanoparticles with no specific requirement on processing deformation, and the plasticity and ductility of the reinforcing phase. Furthermore, it has simple processes, low cost and no particular requirements on the equipment. Contact materials prepared by the present method have good resistance to welding and arc erosion, conductivity and a greatly enhanced processing performance.