CMC Surface Protection via Slurry Barrier Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ceramic matrix composite (CMC) materials face challenges in protecting near-surface reinforcement materials from damage due to handling, machining, and high-temperature oxidation, as these areas are susceptible to mechanical and chemical degradation, compromising the mechanical and thermal properties of the composite.
Innovation Solution
A protective outer barrier layer is formed using a slurry containing particulate material, including carbon-containing filamentary materials, which is heated to create a ceramic layer compatible with the CMC substrate, covering the reinforcement material and preventing damage while allowing for aggressive surface treatments like grit blasting and high-temperature exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a CMC article is fabricated with reinforcement material exposed at the surface to maximize load-bearing capability, then the mechanical strength is improved, but the near-surface reinforcement material becomes susceptible to damage from handling, machining, and oxidation
Solution Approach 1:
The CMC article is segmented into distinct functional layers: an inner layer containing reinforcement material for load-bearing, and an outer protective layer without reinforcement material that shields the inner layer from damage and oxidation. This segmentation allows each layer to optimize its specific function without compromise.
Solution Approach 2:
The protective outer layer is applied locally at the surface regions where reinforcement material would be exposed, providing targeted protection only where needed. The inner load-bearing regions maintain their reinforcement structure while the surface regions gain protective coverage.
2Ease of manufacture
If the CMC article undergoes aggressive surface treatments like grit blasting to prepare for environmental barrier coatings, then the surface preparation is improved, but the near-surface reinforcement material is at risk of mechanical damage
Solution Approach 1:
A protective layer is applied in advance before surface treatment operations, creating a sacrificial barrier that can withstand aggressive grit blasting and other mechanical surface preparations. This preliminary protective action enables subsequent manufacturing steps to proceed without damaging the underlying reinforcement material.
3Temperature
If the CMC article is exposed to high-temperature environments to achieve desired thermal properties, then the thermal performance is improved, but the near-surface reinforcement material becomes vulnerable to oxidation and chemical degradation
Solution Approach 1:
A protective outer layer acts as an intermediary barrier between the reinforcement material and the high-temperature oxidizing environment. This intermediate layer protects the reinforcement from direct exposure to harmful chemical factors while allowing the CMC article to achieve its desired thermal performance.
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 protective layer effectively shields near-surface reinforcement materials from damage, maintains mechanical and thermal integrity, and facilitates surface preparation for environmental barrier coatings, extending the composite's lifespan against mechanical degradation.
Implementation Method 1
heating to a temperature sufficient to pyrolyze the organic binders and convert the surface layer to the protective layer
Implementation Method 2
heating to form a CMC article comprising a ceramic protective layer on a ceramic matrix composite substrate
Implementation Method 3
the carbon-containing filamentary material reacts with oxygen during heating to form carbon dioxide
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A CMC article (18) and process for producing the article (18) to have a layer (22) on its surface that protects a reinforcement material (15) within the article (18) from damage. The method entails providing a body containing a ceramic reinforcement material (15) in a matrix material that contains a precursor of a ceramic matrix material (16). A fraction of the reinforcement material (15) is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material (15) of the body. The body and surface layer are heated to form the article (18) by converting the precursor within the body to form the ceramic matrix material (16) in which the reinforcement material (15) is contained, and by converting the surface layer to form the protective layer (22) that covers any fraction of the reinforcement material (15) exposed at the body surface.