Vacuum Infiltration of Ceramic Matrix Composites

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Solution Overview

Problem

The existing methods for vacuum infiltration of ceramic matrix composites face challenges with high residual porosity and viscosity issues due to solvent evaporation, which affects the infiltration of high solid loading slurries and results in weaker CMC components.

Innovation Solution

A system and method for vacuum infiltration that includes a chamber with a slurry confinement fixture, where a solvent is added to achieve equilibrium partial pressure to prevent evaporation, and a slurry with high solid loading and small particle sizes is used, with pressure manipulation to drive the slurry into the porous preform, ensuring complete infiltration without significant viscosity increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high solid loading slurry is used for infiltration, then the mechanical properties of CMC components are improved, but the viscosity of the slurry increases making infiltration difficult

Engineering Contradiction:

Improvemechanical properties of CMC componentsVSAvoidinfiltration processability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the physical parameters of the slurry by reducing particle size to sub-micron range (0.1-10 micrometers) and controlling solid loading content, which transforms the viscosity characteristics of the slurry to enable both high mechanical properties and ease of infiltration

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the porous structure of the preform with controlled pore size and distribution to facilitate slurry infiltration, where the porous architecture enables capillary action and pressure-driven flow of high solid loading slurries without requiring excessive pressure

Inventive Principle:

Principle #31Porous materials

2Ease of manufacture

If solvent evaporation is allowed during infiltration, then the infiltration process is simpler, but residual porosity increases and mechanical properties deteriorate

Engineering Contradiction:

Improveinfiltration process simplicityVSAvoidmechanical properties of CMC components

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent creates an inert atmosphere within the infiltration chamber by establishing equilibrium partial pressure of the solvent, which prevents solvent evaporation and maintains a controlled environment that eliminates residual porosity while preserving infiltration simplicity

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The patent utilizes phase transition equilibrium by controlling the solvent vapor pressure to match the equilibrium partial pressure, preventing liquid-to-vapor phase transition (evaporation) during infiltration, thereby maintaining slurry integrity and preventing void formation

Inventive Principle:

Principle #36Phase transitions

3Manufacturing precision

If pressure is increased to drive slurry into preform, then infiltration completeness is improved, but the risk of slurry splashing and contamination increases

Engineering Contradiction:

Improveinfiltration completenessVSAvoidslurry splashing and contamination

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a slurry confinement fixture as an intermediary device between the pressure source and the preform, which contains the slurry during pressurization and directs it into the preform through controlled pathways, ensuring complete infiltration while preventing splashing and contamination

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This approach allows for the successful infiltration of high solid loading slurries with small particle sizes, reducing residual porosity and enhancing the mechanical properties of the CMC components, resulting in stronger and more desirable finished products.

Implementation Method 1

A vacuum is created in the chamber

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

A solvent is added to the chamber until a pressure in the chamber is substantially equal to an equilibrium partial pressure of the solvent

Methodology Applied

Scientific EffectEquilibrium partial pressure: Vapour Pressure

Implementation Method 3

The pressure in the chamber is increased to urge the slurry into the porous preform

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS11161792B2Vacuum infiltration system for ceramic matrix composites

Publication Date: 2021.11.02 ROLLS ROYCE HIGH TEMPERATURE COMPOSITES INC

AI summary

A method for infiltrating a porous preform for a gas turbine engine is provided, which comprises providing a chamber for infiltrating a porous preform. The porous preform is positioned within a slurry confinement fixture within the chamber. A vacuum is created in the chamber. A solvent is added to the slurry confinement fixture until a pressure in the chamber is substantially equal to an equilibrium partial pressure of the solvent. A slurry is added to the slurry confinement fixture. The slurry includes the solvent and a particulate. The pressure in the chamber is increased, and the slurry is urged into the porous preform.