Conductive Fastener Coating for CFRP Bonding and Corrosion Protection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing aerospace coatings for fasteners and components lack chromate-free solutions that provide low electrical resistivity for electrical grounding and bonding, are compatible with aluminum and carbon fiber reinforced polymer (CFRP) structures, and meet interference fit applications without compromising paint adhesion and corrosion protection.

Innovation Solution

A coating system comprising a conductive layer, such as a nickel flash layer, combined with a resin-based layer containing conductive pigments, like nickel fibers, which form a 3D-network for enhanced electrical conductivity and corrosion resistance, suitable for titanium, stainless steel, and nickel-chromium-based superalloys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If chromate-based coatings are used for corrosion protection, then corrosion protection is improved, but environmental compliance and compatibility with CFRP structures deteriorate

Engineering Contradiction:

Improvecorrosion protectionVSAvoidenvironmental harm and CFRP compatibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes chromate from the coating formulation entirely, extracting the harmful substance while retaining the protective function through alternative mechanisms using chromate-free resin systems and metallic pigments

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses composite coating formulations combining organic resins with metallic pigments (aluminum, zinc, nickel) to achieve both corrosion protection and environmental compliance, replacing the simple chromate-based systems

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional metal coatings are used for electrical conductivity, then electrical conductivity is improved, but paint adhesion and interference fit compatibility deteriorate

Engineering Contradiction:

Improveelectrical conductivityVSAvoidpaint adhesion and interference fit compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent develops composite coatings integrating metallic conductive pigments within organic resin matrices, combining the electrical conductivity of metals with the adhesion and flexibility of polymers

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The coating formulation uses specific metallic pigments (aluminum, zinc, nickel) dispersed in resin to provide localized electrical conductivity pathways while the resin matrix maintains overall coating adhesion and compatibility

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If resin-based conductive coatings are used, then paint adhesion is improved, but electrical conductivity deteriorates

Engineering Contradiction:

Improvepaint adhesionVSAvoidelectrical conductivity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention creates composite coatings with conductive metallic pigments embedded in resin matrices, where the pigment concentration and distribution are optimized to provide electrical conductivity pathways while maintaining resin-based adhesion properties

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The coating provides localized conductive pathways through dispersed metallic pigments within the resin matrix, allowing different regions of the coating to fulfill different functions (adhesion vs. conductivity)

Inventive Principle:

Principle #3Local quality

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 coating system achieves low electrical resistivity, galvanic corrosion protection, and compatibility with both metallic and CFRP structures, while maintaining paint adhesion and facilitating interference fit applications, meeting regulatory requirements.

Implementation Method 1

The coating system includes a conductive layer on the base metal and a resin-based layer including a conductive pigment layered on the conductive layer. The conductive pigments form three-dimensional electrically conductive networks that are randomly distributed in the resin-based layer.

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The coating system includes a metal flash layer on at least part of the metal of the component. The metal flash layer serves as a conductive base for subsequent coating layers.

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS20250312819A1Methods for coating and components having coatings for electrical conductivity

Publication Date: 2025.10.09 LISI AEROSPACE

AI summary

A metal component made of a base metal and a coating system thereon is characterized in that the coating system comprises a conductive layer on the base metal and a resin-based layer including conductive pigments on the conductive layer. The conductive pigments form electrically conductive 3D-networks in the resin, with the networks being randomly distributed in the resin. Aerospace fasteners having a coating system of a nickel flash on the base metal, and a phenolic resin-based coating including nickel fibers on the nickel flash, are also provided. Further, a method for coating a metal component is disclosed. The coating system may be applied to metal components, including aerospace fasteners such as pins, bolts, collars, nuts and nut plates, and washers, as well as studs, latches, helicopter rotors, and landing gear structures.