Vacuum Plasma Sprayed Coating with Dispersed Silica Phase
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Solution Overview
Problem
Ceramic and ceramic matrix composite materials used in high-temperature mechanical systems, such as gas turbine engines, can react with water vapor, leading to material recession and reduced mechanical properties, necessitating the development of effective environmental barrier coatings.
Innovation Solution
A method involving vacuum plasma spray physical vapor deposition (PS PVD) is used to form a coating with a dispersed silica phase by introducing a controlled amount of oxygen as a reactive gaseous species into a high-vacuum chamber, where it reacts with silicon metal to create a tough and crack-resistant silica phase within the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic or CMC materials are used in high-temperature mechanical systems, then mechanical strength and heat resistance are improved, but chemical stability deteriorates due to reaction with water vapor
Solution Approach 1:
A silicon-containing environmental barrier coating is applied as an intermediary layer between the ceramic/CMC substrate and the water vapor environment. The coating reacts with water vapor to form a protective silica-rich glassy phase that prevents direct attack on the substrate, thereby maintaining both high-temperature performance and chemical stability.
Solution Approach 2:
The coating is designed as a composite material containing silicon-containing glass particles dispersed in a matrix. This composite structure provides both the mechanical integrity needed for high-temperature service and the chemical reactivity with water vapor to form protective silica phases, thus resolving the contradiction between heat resistance and chemical stability.
2Reliability
If environmental barrier coating is applied to protect ceramic/CMC substrate, then chemical stability is improved, but manufacturing complexity increases
Solution Approach 1:
The coating formulation is designed in advance with pre-selected silicon-containing glass particles and controlled stoichiometry. The coating is applied as a pre-mixed slurry or suspension that automatically forms the desired protective silica-rich phase upon exposure to water vapor during service, eliminating the need for complex post-deposition processing steps.
Solution Approach 2:
The coating is designed to be self-protecting by incorporating silicon-containing glass particles that automatically react with water vapor to form a protective silica-rich glassy phase. This self-service mechanism eliminates the need for complex external protection systems or frequent maintenance interventions, simplifying the overall manufacturing process.
3Manufacturing precision
If reactive gaseous species are introduced during plasma spray deposition, then silica phase formation is improved, but process complexity increases
Solution Approach 1:
The patent introduces reactive gaseous species (oxygen-containing gases) during the plasma spray deposition process to control the oxidation state of silicon and promote silica phase formation. By adjusting gas flow rates, pressure, and composition, the process achieves precise control over silica phase formation and coating properties without requiring complex multi-step processing.
Solution Approach 2:
The deposition process is merged with in-situ oxidation by introducing reactive gaseous species during plasma spray. This combines the coating deposition and silica phase formation steps into a single integrated process, eliminating the need for separate oxidation treatments and reducing overall process complexity while maintaining manufacturing precision.
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 technique enhances the mechanical and chemical properties of the coating, including toughness and resistance to crack propagation, thereby extending the useful lifetime of high-temperature components by forming a robust environmental barrier.
Implementation Method 1
controlling a plasma spray device to deposit a coating on a substrate in the vacuum chamber using plasma spray physical vapor deposition
Implementation Method 2
a plasma jet is generated in that a plasma gas is conducted through the plasma torch and is heated therein by means of electric gas discharge
Implementation Method 3
The reactive gaseous species react with silicon metal of the coating material to form a dispersed silica phase in at least part of the coating
Data Source
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AI summary
A technique may include controlling a vacuum pump to evacuate a vacuum chamber to high vacuum; controlling a plasma spray device to deposit a coating on a substrate in the vacuum chamber using plasma spray physical vapor deposition; and controlling a source of a reactive gaseous species to introduce a controlled amount of the reactive gaseous species into the vacuum chamber during the plasma spray physical vapor deposition process. The reactive gaseous species may react with at least one constituent of the coating to form a dispersed phase in at least part of the coating.