CVI Tooling Windows and Inner Holes for Uniform Infiltration

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Solution Overview

Problem

In chemical vapor infiltration (CVI) processes, traditional tooling with uniform hole lengths is inadequate for complexly-shaped preforms like turbine airfoils, as vaporous precursors struggle to infiltrate uniformly, leading to inefficiencies in densification.

Innovation Solution

A tooling assembly comprising an outer fixture with windows aligned with inner fixture holes of varying lengths, creating a wider flow path for vaporous precursors to ensure uniform infiltration, with the outer tooling fixture having windows that overlap with inner holes to enhance precursor access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If uniform hole lengths are used in tooling, then manufacturing simplicity is maintained, but infiltration uniformity deteriorates for complexly-shaped preforms

Engineering Contradiction:

Improveinfiltration uniformityVSAvoidtooling structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The tooling is divided into multiple segments (outer tooling with windows and inner tooling with holes) that can be independently designed and positioned. This segmentation allows each component to have optimized features - the outer tooling provides wide windows for overall access while the inner tooling provides targeted hole infiltration paths, resolving the contradiction between uniform infiltration and manufacturing simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner tooling fixture with holes is nested within the outer tooling fixture with windows. This nested configuration allows the vapor flow paths to be hierarchical - precursors enter through outer windows and are directed through inner holes, creating varied effective lengths without requiring complete redesign of the entire tooling structure. This maintains manufacturing simplicity while achieving infiltration uniformity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Strength

If long holes are used in tooling, then structural integrity is improved, but precursor infiltration capability deteriorates

Engineering Contradiction:

Improvetooling structural integrityVSAvoidprecursor infiltration rate

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The invention transitions from a single-dimension hole length parameter to a two-dimensional flow path system combining outer windows and inner holes. This dimensional change allows the effective infiltration path to be optimized independently from the structural hole length - structural integrity is maintained through adequate hole lengths while infiltration efficiency is improved by adding the window dimension that provides additional access pathways.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If short holes are used in tooling, then precursor infiltration is improved, but structural integrity deteriorates

Engineering Contradiction:

Improveprecursor infiltration rateVSAvoidtooling structural integrity

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The outer tooling windows and inner tooling holes are merged to create a combined flow path system. This merging allows the structural function (provided by the inner holes with adequate length) and the infiltration function (enhanced by outer windows providing additional access) to work together synergistically, resolving the contradiction between infiltration rate and structural integrity.

Inventive Principle:

Principle #5Merging (Combining)

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 design improves the mass transfer of vaporous precursors, ensuring uniform densification and preventing reactant deposition, thereby extending tooling life and facilitating the production of complex-shaped ceramic matrix composite parts.

Implementation Method 1

chemical vapor infiltration (CVI)... Holes in the tooling allow vaporous precursors to infiltrate into the preform for the deposition of a ceramic matrix

Methodology Applied

Scientific EffectChemical vapor infiltration: Permeation

Implementation Method 2

vaporous precursors to infiltrate into the preform for the deposition of a ceramic matrix

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Data Source

PatentUS11993548B2Minimization of chemical vapor infiltration tooling hole length through windows

Publication Date: 2024.05.28 RTX CORP

AI summary

A tooling assembly suitable for use in infiltrating a fibrous preform comprises an outer tooling fixture with a plurality of outer sidewalls defining an inner volume, each of the plurality of outer sidewalls having an outer wall thickness, and a window extending through the outer wall thickness of at least one outer sidewall of the plurality of sidewalls. The tooling assembly further comprises an inner tooling fixture positioned within the inner volume of the outer tooling fixture, the inner tooling having a plurality of inner sidewalls, each of the plurality of inner sidewalls having an inner wall thickness, and a plurality of holes extending through the inner wall thickness of at least one inner sidewall of the plurality of inner sidewalls. The at least one outer sidewall is positioned adjacent the at least one inner sidewall such that the window overlaps with at least a subset of the plurality of holes in the at least one inner sidewall.