Multi-Layered Coating for Threaded Fastener Anti-Seize

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Solution Overview

Problem

Existing anti-seize coatings for threaded components, such as silver and dry film lubricants, face issues with deformation during assembly, corrosion, health concerns, and variability in performance, leading to inconsistent assembly and disassembly torques and potential corrosion problems.

Innovation Solution

A multi-layered coating using vapour deposition of titanium, chromium, nickel, platinum, and tantalum, with optional ion implantation, applied in thin layers to provide high mechanical strength, thermal stability, and corrosion resistance, mimicking shear properties of silver and dry film lubricants without deformation or interference with engineering tolerances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silver or silver-based coatings are applied to threaded portions, then anti-seize capability and friction reduction are improved, but mechanical deformation during assembly and corrosion problems occur

Engineering Contradiction:

Improveanti-seize capabilityVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies a multi-layered coating system combining silver with other materials (such as nickel, copper, or zinc layers) to create a composite structure. The silver layer provides anti-seize capability while the supporting layers provide mechanical strength and corrosion resistance, resolving the contradiction between soft lubricating properties and structural integrity.

Inventive Principle:

Principle #40Composite materials

2Reliability

If dry film lubricants are applied to threaded portions, then friction reduction is achieved, but large variability in composition and coverage results

Engineering Contradiction:

Improvefriction reductionVSAvoidcomposition and coverage consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical application methods (brush, spray, dip) with electroplating technology. This substitution ensures uniform thickness control, consistent composition, and precise coverage through electrical current distribution, eliminating the variability inherent in manual or spray application methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If silver compounds are used to prevent seizure under high local loading, then anti-seize performance is improved, but health concerns and corrosion problems arise

Engineering Contradiction:

Improveseizure preventionVSAvoidhealth concerns and corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces intermediate barrier layers (such as nickel or copper) between the silver coating and the base metal, and between the silver and the environment. These intermediary layers prevent direct contact between silver compounds and harmful substances (sulphur, chlorine), eliminating corrosion pathways while maintaining the silver layer's seizure prevention capabilities.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If coating thickness is increased to 5-20 microns to accommodate mechanical deformation, then anti-seize performance is maintained, but assembly torque variability increases

Engineering Contradiction:

Improveanti-seize performanceVSAvoidassembly torque control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The multi-layered composite structure allows for a thinner total coating thickness because the rigid supporting layers provide dimensional stability. This prevents the excessive deformation that occurs with thick silver-only coatings, thereby maintaining consistent assembly torque while preserving anti-seize performance through the silver layer's lubricating properties.

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 multi-layered coating offers precise and repeatable control over assembly properties, enhanced lubrication performance, and corrosion resistance, eliminating deformation and health hazards while maintaining the low friction and anti-seize properties of silver and dry film lubricants.

Implementation Method 1

using a vapour deposition process to apply a multi-layered coating to the threaded portion

Methodology Applied

Scientific EffectVapour deposition: Physical Vapour Deposition

Implementation Method 2

This enables the multi-layered coating to provide a low friction, anti-seize property to an assembled joint between threaded components coated with the multi-layered coating

Methodology Applied

Scientific EffectShear bands: Shear Stress

Implementation Method 3

The use of a multi-layered coating in which the coating material is selected from the group comprising titanium, chromium, nickel, platinum, tantalum, and combinations thereof, provides shear bands at the interfaces between the discrete layers of the coating material

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Data Source

PatentUS10316882B2Coating for a threaded component and a method of applying the same

Publication Date: 2019.06.11 ROLLS ROYCE PLC

AI summary

A method of providing a threaded fastener with a multi-layered coating comprises the step of using a vapor deposition process to apply a multi-layered coating to a threaded portion of the threaded fastener, each layer of the multi-layered coating being formed from a coating material selected from the group comprising titanium, chromium, nickel, platinum, tantalum, and combinations thereof.