CMAS-Resistant Turbomachine Coating with Rare Earth Silicate Particles
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Solution Overview
Problem
Turbomachine parts coated with thermal or environmental barrier coatings degrade rapidly when exposed to environments rich in calcium, magnesium, aluminum, and silicon (CMAS) particles, leading to infiltration and mechanical failure due to the formation of secondary phases with different mechanical properties.
Innovation Solution
A coated turbomachine part with a protective layer comprising a first phase capable of forming apatite or anorthite phases and a second phase of rare earth silicate particles, which enhances the reactivity of the layer to confine CMAS reactions and limit penetration, thereby reducing the formation of secondary phases and increasing the layer's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-CMAS compositions are used to form a protective barrier layer through chemical reaction with CMAS, then the protective effect against CMAS infiltration is improved, but secondary phases with significant volumes and poor mechanical properties are formed
Solution Approach 1:
The patent applies local quality by creating a reaction zone with concentrated rare earth silicate particles near the coating surface where CMAS infiltration occurs. This localized concentration of reactive particles ensures that the chemical reaction with CMAS happens primarily in this specific zone, forming the blocking apatite phase where it is most needed while limiting the spread of secondary phases into the bulk coating material.
Solution Approach 2:
The patent changes the chemical composition parameters of the protective layer by incorporating rare earth silicate particles (1-50 μm size) into the CMAS-reactive material. This compositional modification alters the reaction kinetics and phase formation characteristics, enabling the system to form protective apatite phases more rapidly while controlling the volume and distribution of secondary phases through precise compositional control.
2Duration of action of stationary object
If rare earth silicate particles are added to increase reactivity and limit CMAS penetration, then the service life of the protective layer is increased, but the device complexity increases
Solution Approach 1:
The patent employs composite materials by combining rare earth silicate particles with CMAS-reactive matrix materials to create a multi-phase protective coating. This composite structure leverages the high reactivity of rare earth silicates for rapid apatite formation while the matrix material provides structural support and additional CMAS reaction capability, achieving extended service life through synergistic material combination.
Solution Approach 2:
The patent applies preliminary action by pre-incorporating rare earth silicate particles into the protective layer before CMAS exposure. These particles are positioned in advance within the coating matrix, ready to react immediately upon CMAS contact. This pre-positioning eliminates the need for complex in-situ generation mechanisms and simplifies the overall system while ensuring rapid protective phase formation when needed.
3Loss of substance
If the protective layer is designed to confine CMAS reaction to the surface vicinity, then the formation of secondary phases is limited, but the manufacturing precision requirements increase
Solution Approach 1:
The patent addresses reaction zone confinement by transitioning from a two-dimensional surface coating concept to a three-dimensional structured coating with vertically distributed rare earth silicate particles. This dimensional approach allows the reactive particles to be positioned at optimal depths within the coating matrix, creating a volumetric reaction zone that naturally confines CMAS reactions through the coating thickness rather than relying solely on surface-level control.
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 addition of rare earth silicate particles in the protective layer increases the reactivity and longevity of the anti-CMAS coating by limiting CMAS infiltration and reducing mechanical stresses, maintaining the protective effect while minimizing the formation of secondary phases that compromise the coating's integrity.
Implementation Method 1
The anti-CMAS compositions used will undergo dissolution in CMAS to form a dense protective phase with a higher melting point than that of CMAS
Implementation Method 2
a ceramic coating whose primary function is to limit the surface temperature of the coated components
Implementation Method 3
the undercoat is pre-oxidized to form a dense alumina layer on its surface, known as Thermally Grown Oxide (TGO)
Data Source
Figure 1A~2B
Figure 3~4
Figure 5~6
AI summary
A coated turbomachine part (20) comprises a substrate (21) and a layer for protection against the calcium and magnesium aluminosilicates CMAS (22) present on the substrate (21). The protective layer (22) comprises a first phase (220) of a material for protection against the calcium and magnesium aluminosilicates CMAS, capable of forming an apatite- or anorthite-type phase in the presence of calcium and magnesium aluminosilicates CMAS, and a second phase (221) comprising particles of at least one rare earth silicate REa dispersed in the first phase.