Low-ice-adhesion coating with phase-separated microstructure

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Solution Overview

Problem

Current low-ice-adhesion coatings for aerospace applications lack durability and effectiveness in reducing ice adhesion, with existing solutions often requiring regular reapplication and offering limited long-term protection against ice formation on critical aircraft surfaces.

Innovation Solution

A low-ice-adhesion material comprising a continuous matrix with dispersed inclusions, featuring a fluoropolymer and a hygroscopic material, forming a phase-separated microstructure that reduces ice adhesion, characterized by an AMII Centrifuge Ice Adhesion Reduction Factor of 10 or more, achieved through a combination of low-surface-energy polymers and hygroscopic components like poly(acrylic acid) and poly(ethylene glycol).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If sacrificial oils or greases are used to reduce ice adhesion, then ice adhesion is reduced, but the coating requires regular reapplication due to limited lifetime

Engineering Contradiction:
Improveice adhesionVSAvoidcoating lifetime
Core Design Contradiction:
Object-affected harmful factorsVSDuration of action of stationary object

Solution Approach 1:

The patent employs a composite material system consisting of a thermoplastic elastomer matrix combined with hydrophilic particles (such as PEG, PVA, or cellulose derivatives). This composite structure integrates the adhesive properties of the elastomer with the ice-phobic characteristics of the hydrophilic particles, creating a coating that maintains both durability and ice adhesion reduction without requiring sacrificial oils or greases.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the surface energy characteristics of the coating by incorporating hydrophilic particles with specific surface properties into the thermoplastic elastomer matrix. This parameter change enables the coating to exhibit low ice adhesion through controlled surface energy distribution, achieving lasting icephobicity without the need for periodic reapplication of sacrificial materials.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If deicing fluids are applied to remove ice, then existing ice contamination is removed, but the fluid provides no inflight protection and must be sheared off during takeoff

Engineering Contradiction:
Improveice contaminationVSAvoidprotection duration
Core Design Contradiction:
Object-affected harmful factorsVSDuration of action of stationary object

Solution Approach 1:

The patent applies a durable icephobic coating to aircraft surfaces before flight operations. This preliminary protective action creates a lasting barrier that prevents ice adhesion during flight, eliminating the need for subsequent deicing fluid applications and mechanical removal during takeoff. The coating provides continuous protection throughout the flight mission.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The coating system provides self-service ice protection by maintaining its icephobic properties throughout the flight duration. The thermoplastic elastomer matrix with hydrophilic particles automatically resists ice adhesion without requiring additional deicing fluids or mechanical intervention, enabling the aircraft to maintain ice-free critical surfaces throughout the flight.

Inventive Principle:
Principle #25Self-service

3Duration of action of stationary object

If thermoplastic elastomers with film adhesive are used for coating, then durable coating is achieved, but there is no benefit in lowering ice adhesion

Engineering Contradiction:
Improvecoating durabilityVSAvoidice adhesion reduction
Core Design Contradiction:
Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent merges two previously separate functions into a single integrated coating system: (1) the thermoplastic elastomer matrix provides durable adhesion to the substrate, and (2) the incorporated hydrophilic particles provide ice adhesion reduction. This combination eliminates the need for separate adhesive layers while simultaneously achieving both durability and icephobicity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermoplastic elastomer matrix serves multiple functions: it provides structural integrity, ensures durable adhesion to the substrate, and when combined with hydrophilic particles, delivers ice adhesion reduction. This multi-functional material system replaces the need for separate adhesive and ice-protection layers, achieving both durability and icephobicity in a single coating.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 material significantly delays ice formation and reduces ice adhesion, providing durable and long-term protection against ice accumulation on aircraft surfaces, with an AMII Centrifuge Ice Adhesion Reduction Factor of 10 or more, outperforming existing solid coatings by up to 100 times in ice adhesion reduction.

Implementation Method 1

one of the first component or the second component is a low-surface-energy polymer having a surface energy between about 5 mJ/m2 and about 20 mJ/m2

Methodology Applied
Scientific EffectLow-surface-energy polymer effect: Surface Tension

Implementation Method 2

hygroscopic components like poly(acrylic acid) and poly(ethylene glycol)

Methodology Applied
Scientific EffectHygroscopic effect: Absorption (physical)

Data Source

PatentEP4039757B1Compositions and methods for fabricating durable, low-ice-adhesion coatings
Publication Date: 2023.12.27 HRL LAB
  • EP4039757B1 patent drawingFigure 1
  • EP4039757B1 patent drawingFigure 2A
  • EP4039757B1 patent drawingFigure 2B

AI summary

This invention provides durable, low-ice-adhesion coatings with excellent performance in terms of ice-adhesion reduction. Some variations provide a low-ice-adhesion coating comprising a microstructure with a first-material phase and a second-material phase that are microphase-separated on an average length scale of phase inhomogeneity from 1 micron to 100 microns. Some variations provide a low-ice-adhesion material comprising a continuous matrix containing a first component; and a plurality of discrete inclusions containing a second component, wherein the inclusions are dispersed within the matrix to form a phase-separated microstructure that is inhomogeneous on an average length scale from 1 micron to 100 microns, wherein one of the first component or the second component is a low-surface-energy polymer, and the other is a hygroscopic material. The coatings are characterized by an AMIL Centrifuge Ice Adhesion Reduction Factor up to 100 or more. These coatings are useful for aerospace surfaces and other applications.