Vibration-Assisted CVD for Uniform Coating on Fibrous Preforms

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Solution Overview

Problem

Conventional methods for manufacturing ceramic matrix composites (CMCs) using chemical vapor deposition face challenges in achieving uniform deposition of interface coatings and matrix materials due to fiber concatenation during the process, leading to incomplete coverage and increased porosity, which affects the toughness and load-bearing capacity of the composites.

Innovation Solution

Applying vibration to the fiber structure during chemical vapor deposition using a piezoelectric actuator and waveguide to separate fibers and fiber tows, allowing for uniform deposition of the interface coating and matrix material, thereby preventing fiber concatenation and reducing porosity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If chemical vapor deposition is performed on fiber preform without vibration, then the deposition process can proceed continuously, but the fibers concatenate by sintering leading to non-uniform deposition and incomplete coverage

Engineering Contradiction:

Improveuniformity of depositionVSAvoidcomplexity of deposition system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies mechanical vibration to the fiber preform during chemical vapor deposition to prevent fiber concatenation by sintering. The vibration keeps fibers separated, allowing uniform deposition of interface coating and matrix material across all fiber surfaces, thereby improving manufacturing precision without requiring complex system modifications

Inventive Principle:

Principle #18Mechanical vibration

2Manufacturing precision

If vibration is applied to separate fibers during deposition, then uniform coating coverage is achieved, but the device complexity increases due to additional vibration equipment

Engineering Contradiction:

Improvesurface coverage uniformityVSAvoidcomplexity of deposition system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

A piezoelectric actuator coupled with a waveguide is integrated into the deposition system to generate mechanical vibrations at frequencies between 20-20,000 Hz. This relatively simple addition effectively separates fibers during deposition, ensuring uniform surface coverage of interface coating and matrix material without requiring complex system redesign

Inventive Principle:

Principle #18Mechanical vibration

3Ease of manufacture

If fibers are allowed to concatenate during deposition, then the deposition process is simpler, but porosity increases and load-bearing capacity decreases

Engineering Contradiction:

Improvesimplicity of deposition processVSAvoidload-bearing capacity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

Mechanical vibration applied during deposition prevents fiber concatenation by maintaining fiber separation, which reduces porosity and enables complete infiltration of matrix material. This simple vibration mechanism significantly improves load-bearing capacity and structural integrity without complicating the manufacturing process

Inventive Principle:

Principle #18Mechanical vibration

4Manufacturing precision

If interface coating is deposited on individual tows before preform assembly, then coating uniformity is improved, but the process time increases and productivity decreases

Engineering Contradiction:

Improvecoating uniformityVSAvoiddeposition process speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by depositing interface coating on individual fiber tows before preform assembly, ensuring uniform coverage. The vibration technique is then applied during subsequent matrix deposition to maintain fiber separation and achieve uniform matrix infiltration, optimizing both coating uniformity and overall process efficiency

Inventive Principle:

Principle #10Preliminary action

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 method ensures full surface coverage of the interface coating and effective infiltration of the matrix material, enhancing the fracture toughness, resistance to oxidative degradation, and load-bearing capacity of the CMCs by reducing closed porosity and preventing crack propagation.

Implementation Method 1

a piezoelectric actuator and waveguide to separate fibers and fiber tows

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Applying vibration to the fiber structure during chemical vapor deposition using a piezoelectric actuator and waveguide

Methodology Applied

Scientific EffectMechanical vibration: Vibration

Implementation Method 3

chemical vapor deposition

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 4

matter is deposited from vapor onto surfaces

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentEP3502307B1Method of increasing the uniformity of chemical vapor deposition on fibrous material through the imposition of pressure waves

Publication Date: 2021.05.26 RTX CORP

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AI summary

A method of infiltrating a fiber structure with a coating and a matrix material includes connecting a wave guide to a fiber structure comprising a plurality of fibers, applying vibration to the fiber structure to separate adjacent fibers at contact points, and depositing a coating on a surface of each of the fibers including contact point surfaces where adjacent fibers have been separated.