Phosphate Glass Coating for High-Temperature Composite Oxidation

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Solution Overview

Problem

Phosphate-based oxidation protection systems for carbon-carbon composite structures face challenges at high temperatures, including viscosity decrease, migration, and oxidation of components, leading to reduced protection effectiveness, especially on non-wear surfaces of aircraft brake disks.

Innovation Solution

A method involving the formation of a base layer using a first phosphate glass composition and a sealing layer with a strengthening compound like boron nitride, applied through a slurry process, which includes a silica compound to prevent migration and enhance oxidation resistance, forming a borosilicate glass that maintains viscosity and protects against oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phosphate-based oxidation protection systems are applied to carbon-carbon composites, then oxidation protection is provided, but at high temperatures the viscosity decreases causing migration away from non-wear surface edges

Engineering Contradiction:

Improveoxidation protectionVSAvoidviscosity stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical composition parameters of the protection system by incorporating boron nitride (0.1-6 wt%), silica compounds (1-10 wt%), and specific phosphate glass compositions with controlled ratios of P2O5 (40-70 mol%), B2O3 (10-30 mol%), and SiO2 (5-20 mol%). These compositional parameter changes raise the viscosity at operating temperatures and prevent migration while maintaining oxidation protection capabilities.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite protection system combining phosphate glass, boron nitride, and silica compounds in specific proportions. This composite formulation synergistically enhances high-temperature viscosity stability while maintaining oxidation resistance, preventing the migration issue that occurs with conventional phosphate-based systems alone.

Inventive Principle:

Principle #40Composite materials

2Reliability

If phosphate-based oxidation protection systems are used at high temperatures, then oxidation resistance is provided, but components oxidize and evaporate lessening protection capabilities

Engineering Contradiction:

Improveoxidation resistanceVSAvoidcomponent evaporation

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent converts the potential harm of component evaporation into a beneficial self-healing mechanism. The boron nitride and silica compounds form a low-viscosity melt at elevated temperatures that flows into oxidized or damaged areas, then re-solidifies to seal cracks and replenish protective material. This transforms the evaporation phenomenon into a self-repair process that maintains protection capabilities.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The specific compositional parameters—particularly the P2O5/B2O3/SiO2 ratio control and the addition of boron nitride—modify the thermal behavior of the protection system. These parameter changes ensure that evaporation occurs at temperatures higher than normal operating conditions, and that the evaporated components can condense and re-form protective layers on the composite surface.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If oxidation protection systems are applied to non-wear surfaces, then protection is provided, but at high temperatures the system migrates away from edges proximate to wear surfaces

Engineering Contradiction:

Improveprotection effectivenessVSAvoidcoating distribution

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent adjusts the viscosity parameters through compositional modification (adding boron nitride 0.1-6 wt% and silica compounds 1-10 wt%) to prevent temperature-induced migration. These parameter changes ensure the coating maintains its shape and distribution uniformity even at elevated temperatures near wear surfaces, eliminating edge migration while preserving protection effectiveness.

Inventive Principle:

Principle #35Parameter changes

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 effectively reduces weight loss and maintains oxidation protection at high temperatures by preventing migration and oxidation of the protection system, thereby enhancing the durability and effectiveness of the oxidation protection system on carbon-carbon composite structures.

Implementation Method 1

Phosphate-based oxidation protection systems may reduce infiltration of oxygen and oxidation catalysts into the composite structure

Methodology Applied

Scientific EffectOxidation protection: Oxidation

Implementation Method 2

forming a borosilicate glass that maintains viscosity and protects against oxidation

Methodology Applied

Scientific EffectViscosity maintenance:

Implementation Method 3

the solution effectively reduces weight loss and maintains oxidation protection at high temperatures by preventing migration and oxidation of the protection system

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Data Source

PatentUS11453619B2High temperature oxidation protection for composites

Publication Date: 2022.09.27 GOODRICH CORP

AI summary

An oxidation protection system disposed on a substrate is provided, which may comprise a base layer comprising a first pre-slurry composition comprising a first phosphate glass composition, and/or a sealing layer comprising a second pre-slurry composition comprising a second phosphate glass composition and a strengthening compound comprising boron nitride, a metal oxide, and/or silicon carbide.