Lightweight Ball Joint Composite Coatings Friction Wear

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Solution Overview

Problem

Conventional lightweight ball joints made from low-density metals like titanium and aluminum alloys experience friction-related wear and seizing issues due to incompatible frictional behavior, leading to reduced service life and limited load capacity.

Innovation Solution

A lightweight ball joint design featuring a first contact layer with a copper alloy matrix and solid lubricant particles, and a second contact layer with high hardness, along with an adhesion sub-layer and liquid lubricant, to manage friction and wear, with the first contact layer being deposited via thermal spraying and the second via PVD, ensuring stable operation and extended lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If light metals or metal alloys (titanium, aluminum) are used to form the inner and outer rings, then the weight of the ball joint is reduced, but friction-related wear and seizing issues occur due to incompatible frictional behavior

Engineering Contradiction:

Improveweight of ball jointVSAvoidfriction and wear resistance

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent applies composite materials by depositing contact layers with specific frictional properties onto the lightweight metal rings. The first contact layer comprises a metal matrix (such as copper alloy) and particles of solid lubricant (such as PTFE, graphite, or MoS2), while the second contact layer is a thin layer of high hardness material (such as TiAlN). This composite structure combines the low density of lightweight metals with the superior friction and wear resistance of composite contact layers, resolving the contradiction between weight reduction and frictional compatibility.

Inventive Principle:

Principle #40Composite materials

2Reliability

If thin coatings are applied by vapor phase deposition or PVD to improve friction properties, then the friction behavior is improved, but the coatings are rapidly eliminated under heavy load, limiting the operating range

Engineering Contradiction:

Improvefriction propertiesVSAvoidservice life under heavy load

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent applies local quality by creating contact layers with specific local properties optimized for their function. The first contact layer has a metal matrix with embedded solid lubricant particles providing self-lubricating properties, while the second contact layer provides high hardness and wear resistance. This localized functional differentiation ensures that each layer performs its specific role (lubrication and wear resistance) effectively, preventing rapid elimination under heavy load and extending service life.

Inventive Principle:

Principle #3Local quality

3Reliability

If a first contact layer based on PTFE and a second contact layer of TiAlN are used, then friction properties are improved, but the load capacity remains limited

Engineering Contradiction:

Improvefriction propertiesVSAvoidload capacity

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent enhances load capacity through composite materials by incorporating a metal matrix (such as copper alloy) in the first contact layer, which provides structural strength and load-bearing capability. The embedded solid lubricant particles (PTFE, graphite, or MoS2) maintain low friction properties. This composite structure simultaneously achieves improved friction properties and increased load capacity, overcoming the limitation of PTFE-based solutions.

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

The solution provides stable operation, reduced wear, and improved sliding properties, significantly extending the lifespan of the ball joint while maintaining low weight, essential for aeronautical applications.

Implementation Method 1

the first contact layer is deposited on the spherical surface of one of the rings by thermal spraying of a powder comprising particles of solid lubricant

Methodology Applied

Scientific EffectThermal spraying: Plasma Spray

Implementation Method 2

the second contact layer is deposited on the spherical surface of the other ring by a thin layer vapor phase (PVD) deposition process

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentEP2048389B1Light ball-and-socket joint for articulation and method of manufacturing such a joint

Publication Date: 2012.07.25 SKF AEROSPACE FRANCE SAS

Figure 1~2
Figure 3~5

AI summary

This lightweight ball joint comprises a metallic inner ring (3) and outer ring (7), each having a spherical outer surface (3B) and inner surface (7B), respectively. The ball joint also includes a first contact layer (4), applied to the spherical surface (3B) of one (3) of the rings, and a second contact layer (8), applied to the spherical surface (7B) of the other ring (7). According to the invention, the first contact layer (4) has a lower hardness than the second contact layer (8) and a greater thickness than the second contact layer (8), the first contact layer (4) further being adapted to release particles (42) of solid lubricant by friction with the second contact layer (8).