Silicate-Resistant Barrier Coating for Gas Turbine Substrates
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Solution Overview
Problem
Gas turbine engine components, particularly silicon-containing ceramics, face durability issues due to high-temperature and environmental conditions, leading to substrate recession and infiltration by silicate-containing deposits like CMAS, which can cause sintering and spallation in environmental barrier coatings.
Innovation Solution
A silicate-resistant barrier coating system comprising a refractory matrix and a calcium aluminosilicate additive (CAS) dispersed in the matrix, designed to resist infiltration and equilibrate chemically with silicate-containing deposits, is applied to the substrate, enhancing the coating's durability and preventing substrate recession.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional environmental barrier coatings are used to protect silicon-containing ceramic substrates, then thermal insulation is provided, but the coatings suffer from infiltration and chemical reaction by silicate-containing deposits (CMAS) leading to sintering and spallation
Solution Approach 1:
The patent modifies the chemical composition parameters of the barrier coating by incorporating specific amounts of calcium aluminate spinel (0.1-30 mol%) and calcium aluminosilicate (0.1-30 mol%) into the refractory matrix. This compositional parameter change creates a coating that is chemically resistant to silicate deposits while maintaining thermal barrier properties, thereby resolving the contradiction between durability and resistance to silicate infiltration.
Solution Approach 2:
The patent creates a composite barrier coating system consisting of a refractory matrix (such as yttria-stabilized zirconia or hafnia) combined with specific additive phases (calcium aluminate spinel and calcium aluminosilicate). This composite structure provides both the thermal insulation properties of the refractory matrix and the chemical resistance to silicates provided by the additive phases, resolving the contradiction between thermal protection and chemical durability.
2Object-affected harmful factors
If the coating composition is modified to resist silicate infiltration, then chemical resistance is improved, but the coating must maintain thermal insulation properties and bond strength to the substrate
Solution Approach 1:
The patent carefully controls the concentration parameters of calcium aluminate spinel (0.1-30 mol%) and calcium aluminosilicate (0.1-30 mol%) to achieve optimal chemical resistance while maintaining adequate bond strength. The refractory matrix composition is also adjusted (e.g., 70-90 mol% yttria-stabilized zirconia or hafnia) to ensure both chemical inertness and mechanical adhesion, resolving the contradiction between chemical resistance and bond strength.
Solution Approach 2:
The composite coating structure combines a refractory matrix phase that provides mechanical strength and adhesion with calcium aluminate spinel and calcium aluminosilicate additive phases that provide chemical resistance. This multi-phase composite approach allows simultaneous achievement of bond strength and chemical resistance to silicate infiltration.
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 coating system effectively resists infiltration and chemical reaction with silicate-containing deposits, maintaining the substrate's integrity and preventing sintering and spallation, thereby improving the durability and longevity of gas turbine engine components.
Implementation Method 1
The silicate-resistant barrier coating has a composition that is in equilibrium or near equilibrium with the silicate-containing deposit
Data Source
AI summary
A gas turbine engine article includes a substrate and a silicate-resistant barrier coating disposed on the substrate. The silicate-resistant barrier coating is composed of a refractory matrix and a calcium aluminosilicate additive (CAS additive) dispersed in the refractory matrix.