Conductive Resin Coating for Aerospace Fastener Grounding
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Solution Overview
Problem
Current surface treatments for aerospace components, such as fasteners, lack a chromate-free solution that provides low electrical resistivity for grounding and bonding applications while ensuring compatibility with aluminum and carbon fiber reinforced polymer (CFRP) structures.
Innovation Solution
A coating system comprising a conductive layer and a resin-based layer with conductive pigment, specifically designed for aerospace components. The system includes a nickel flash layer and a phenolic resin-based layer with nickel fibers, which form electrically conductive 3D-networks, enhancing electrical conductivity and compatibility with various structural materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional coatings such as IVD aluminum or cadmium are used for corrosion protection, then corrosion resistance is improved, but electrical conductivity deteriorates and chromate is required which is environmentally harmful
Solution Approach 1:
The patent applies composite materials by combining organic resin with conductive metal pigments (such as aluminum, zinc, or nickel particles) to create a coating that exhibits both protective and conductive properties. This composite approach allows the coating to provide corrosion resistance through the resin matrix while maintaining electrical conductivity through the dispersed metal particles, eliminating the need for chromate-based traditional coatings.
Solution Approach 2:
The patent changes the parameters of organic coatings by adjusting the type, size, concentration, and distribution of conductive metal pigments within the resin matrix. By optimizing these parameters, the coating achieves sufficient electrical conductivity for aerospace bonding and grounding applications while maintaining the protective benefits of organic coatings and eliminating environmental hazards associated with chromate.
2Reliability
If chromate-based coatings are used for corrosion protection, then corrosion resistance is improved, but environmental compliance deteriorates
Solution Approach 1:
The patent extracts and eliminates chromate from the coating formulation entirely, replacing it with environmentally compliant alternatives consisting of organic resins and metal pigments. This removal of harmful substances allows the coating to provide equivalent or superior corrosion protection without the environmental and health hazards associated with chromate, thereby achieving environmental compliance.
Solution Approach 2:
The patent converts the previously harmful chromate function (corrosion inhibition) into a beneficial chromate-free system by using organic resin-metal pigment composites. This transformation maintains the protective function while eliminating the harmful aspects, turning an environmentally problematic solution into a compliant one.
3Quantity of substance
If aluminum-pigmented resin coatings are used to improve electrical conductivity, then electrical conductivity is improved, but conductivity is insufficient for bonding and grounding requirements
Solution Approach 1:
The patent changes the parameters of the conductive pigment system by optimizing the metal particle characteristics (type, size, shape, concentration) and their distribution within the resin matrix. By adjusting these parameters, the coating achieves the low electrical resistivity values (e.g., less than 10 milliohms) required for aerospace bonding and grounding applications, surpassing the performance of conventional aluminum-pigmented coatings.
4Reliability
If thick coatings are applied to ensure corrosion protection, then corrosion resistance is improved, but dimensional accuracy deteriorates affecting interference fit applications
Solution Approach 1:
The patent changes the parameter of coating thickness by developing a coating formulation that achieves maximum corrosion protection at minimal thickness. The organic resin-metal pigment composite structure provides efficient corrosion barrier properties that allow thin coating applications to deliver adequate protection without compromising the dimensional accuracy required for interference fit aerospace fasteners.
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, meeting the requirements for electrical grounding and bonding, while being chromate-free and compatible with both metallic and CFRP structures, thus addressing the limitations of existing coatings.
Implementation Method 1
The coating system includes a nickel flash layer and a phenolic resin-based layer with nickel fibers, which form electrically conductive 3D-networks, enhancing electrical conductivity
Data Source
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. Further, a method for coating a metal component is disclosed, and may include depositing a conductive layer on a surface of the component, depositing a resin with electrically conductive pigments on the conductive layer and drying the resin. 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.