Ceramic Matrix Composite Preform Strength via High Char Resin

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Solution Overview

Problem

Existing ceramic matrix composite (CMC) preforms have low strength after burnout due to low char yield from organic binders, and current processes are inefficient with long cycle times and solvent-induced defects.

Innovation Solution

A fast-curing thermosetting resin system with high carbonaceous solids content and minimal solvent use is employed, allowing for quick curing and high carbon char levels, reducing solvent requirements and enabling improved green strength and toughness in CMC preforms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If low char yield slurry composition with polymers that decompose upon heating is used, then the preform is easier to manufacture with minimal solvent, but the preform strength after burnout is low

Engineering Contradiction:

Improvepreform manufacturingVSAvoidpreform strength after burnout

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the slurry by incorporating carbon-containing fillers (graphite, carbon black, charcoal) and high char-yielding polymers (polyacrylonitrile, polyacetylene) to increase carbon char yield from less than 5 wt% to 10-50 wt%, thereby improving preform strength after burnout while maintaining ease of manufacture

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite slurry composition combining organic binders with inorganic carbon-containing fillers (graphite particles, carbon black, charcoal) to achieve both high carbon char yield and adequate green strength, resolving the contradiction between ease of manufacture and preform strength

Inventive Principle:

Principle #40Composite materials

2Strength

If high char yielding resin slurry composition is used, then the preform strength after burnout is improved, but the processing cycle time increases and solvent-induced defects occur

Engineering Contradiction:

Improvepreform strength after burnoutVSAvoidprocessing cycle time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The patent extracts and removes solvent from the slurry composition entirely, using a solvent-free formulation with high solids content (50-80 wt%), which eliminates solvent-induced defects and reduces processing cycle time by removing solvent evaporation and drying steps while maintaining high carbon char yield

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the concentration parameter by formulating a high solids content slurry (50-80 wt% solids) with minimal or no solvent, which accelerates processing by eliminating solvent removal steps and reduces defects while preserving the high carbon char yield needed for preform strength

Inventive Principle:

Principle #35Parameter changes

3Strength

If high solids content slurry is used, then the green strength and toughness are improved, but the solvent removal becomes more critical to avoid defects

Engineering Contradiction:

Improvegreen strengthVSAvoidsolvent-induced defects

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent completely removes solvent from the slurry formulation, using a solvent-free system with 50-80 wt% solids content, which eliminates the harmful effect of solvent-induced defects (voids, bubbles, cracking) while maintaining high green strength and toughness through the concentrated binder and filler matrix

Inventive Principle:

Principle #2Taking out (Extraction)

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 process results in CMC preforms with enhanced strength and reduced porosity, enabling faster production cycles and improved dimensional control, suitable for high-temperature applications like turbine components with reduced defects and increased carbon yield.

Implementation Method 1

a fast-curing thermosetting resin system with high carbonaceous solids content and minimal solvent use is employed, allowing for quick curing

Methodology Applied

Scientific EffectThermosetting resin curing: Chemical Bonding

Implementation Method 2

the carbonaceous solids component provides a suitable amount of carbon char upon pyrolization

Methodology Applied

Scientific EffectPyrolization: Pyrolysis

Implementation Method 3

the precursor slurry composition is applied to the reinforcement material and cured, with the selected resin systems greatly reduce the need for solvents and therefore solvent processing requirements

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS8899939B2Process for producing a ceramic matrix composite article and article formed thereby

Publication Date: 2014.12.02 GENERAL ELECTRIC CO

AI summary

Process for producing a ceramic composite structure includes impregnating a reinforcing material with a suitable precursor slurry composition including thermosetting resin, a suitable curing agent, a ceramic component, a carbonaceous solids component, and optionally, a suitable solvent. Exemplary thermosetting resins include polyesters, vinyl esters, epoxy resins, bismaleimide resins, and polyimide resins. The carbonaceous solids component provides a suitable amount of carbon char upon pyrolization. The preform may be dried prior to curing to remove solvents and thereby provide a working material comprising up to 70 volume % solids. The preform is cured, pyrolized, and infiltrated with molten silicon to form a composite article. The thermosetting resin is selected for processibility, green strength, and relatively fast cure cycle.