CMC Defect Repair with Machinable Coating Before Final Infiltration

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Ceramic matrix composite articles produced through chemical vapor infiltration often exhibit defects or nonconformities, making it difficult to repair them using conventional machining and repair processes, as most methods are unsuitable for these materials.

Innovation Solution

Applying a machinable coating to the nonconforming article, which can be made of materials like rare earth silicates, yttria-stabilized zirconia, or mullite, and machining it to correct geometrical issues or fill defects, followed by completing the infiltration process, allowing for the repair of defects such as dents or size discrepancies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If conventional machining and repair processes are used on ceramic matrix composite articles, then the articles can be repaired, but these processes are unsuitable for ceramic matrix composite components

Engineering Contradiction:

Improverepairability of ceramic matrix composite articlesVSAvoidsuitability of machining processes for ceramic matrix composite components

Core Design Contradiction:

Ease of repairVSEase of manufacture

Solution Approach 1:

A machinable coating layer is applied as an intermediary between the ceramic matrix composite article and the machining process. This coating layer can be easily machined using conventional processes while protecting the underlying CMC material, enabling repair without direct machining of the fragile CMC components

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface properties of the CMC article are changed by applying a coating layer with different machinability characteristics. This allows the surface to be processed with conventional machining tools while the bulk material retains its CMC properties, resolving the contradiction between repairability and manufacturing suitability

Inventive Principle:

Principle #35Parameter changes

2Ease of repair

If a machinable coating is applied and machined to repair nonconformances, then defects can be corrected, but the article requires additional processing steps

Engineering Contradiction:

Improveability to correct defects and nonconformancesVSAvoidnumber of processing steps in repair process

Core Design Contradiction:

Ease of repairVSDevice complexity

Solution Approach 1:

The machinable coating is applied in advance before the final infiltration process. This preliminary action allows defects to be corrected during the repair process while the coating is still accessible, integrating the repair function into the manufacturing sequence rather than adding post-processing steps

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

Enables the repair of ceramic matrix composite articles by filling in defects and adjusting geometry, effectively salvaging otherwise discardable components and ensuring the integrity of the material throughout the process.

Implementation Method 1

flowing reactive gases through the reactor to infiltrate ceramic-based matrix material into the preform

Methodology Applied

Scientific EffectChemical vapor infiltration: Chemical Vapour Deposition

Data Source

PatentEP4385969A1Article and method of making an article by chemical vapor infiltration

Publication Date: 2024.06.19 RTX CORP

Figure 1
Figure 2~3

AI summary

A method of repairing a nonconforming article (102) includes applying a machinable coating (106) to an article (102) with a nonconformance (104). The article (102) includes a preform at least partially infiltrated with a matrix material, to form a repaired article (100). The method also includes machining the machinable coating (106) and completing infiltration of the repaired article (100) with the matrix material. A method of repairing an article (100) is also disclosed.