Thermal Barrier Coating Cold Spray Oxidation
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Solution Overview
Problem
Current methods for depositing thermal barrier coatings (TBCs) in gas turbines face challenges in achieving desired porosity while maintaining mechanical strength, and existing chemistries with low thermal conductivity, such as lanthana, are difficult to deposit due to the formation of a glass phase that disrupts the spraying process.
Innovation Solution
A process involving cold spraying a substrate with a feedstock in a region with an oxygen concentration of at least 10%, concurrently oxidizing the substrate, feedstock, and thermal barrier coating, which includes using ceramic particles and a binder to form a thermal barrier coating with graded porosity and increased oxide content, allowing for controlled microstructure and reduced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If current methods of TBC deposition (EBPVD or APS) are used to increase porosity, then thermal conductivity decreases, but mechanical strength deteriorates
Solution Approach 1:
The invention changes the deposition parameters by using cold spray technology with specific particle velocities and temperatures, along with controlling oxygen concentration during deposition, to achieve a unique microstructure that simultaneously provides high porosity and maintained mechanical strength, resolving the trade-off between thermal insulation and structural integrity
Solution Approach 2:
The invention creates a composite microstructure within the TBC comprising ceramic particles, metal particles, and oxide phases distributed in a specific configuration. This composite structure achieves both high porosity for thermal insulation and sufficient mechanical strength through the synergistic combination of different material phases
2Loss of energy
If TBC chemistry uses low thermal conductivity constituents like lanthana, then thermal insulation improves, but deposition process deteriorates due to glass phase formation
Solution Approach 1:
The invention replaces the conventional thermal-based deposition processes (EBPVD, APS) with cold spray technology, which uses kinetic energy of accelerated particles instead of thermal energy. This substitution avoids the glass phase formation problem that occurs with lanthana-based chemistries in thermal processes, enabling successful deposition of low thermal conductivity materials
Solution Approach 2:
The invention changes the chemical composition parameters by selecting specific ceramic and metal particle combinations that are compatible with cold spray deposition, avoiding constituents that form problematic glass phases while maintaining low thermal conductivity. The process controls oxygen concentration and particle temperature to achieve desired oxide content without process disruption
3Manufacturing precision
If cold spray is used to deposit TBC, then process control improves, but ceramic retention deteriorates without concurrent oxidation
Solution Approach 1:
The invention merges the cold spray deposition process with concurrent oxidation by controlling oxygen concentration in the deposition region. This combination allows the metallic binder to oxidize during deposition, creating strong chemical bonds with ceramic particles and improving ceramic retention while maintaining the advantages of cold spray process control
Solution Approach 2:
The invention introduces elevated oxygen concentration (at least 10%) in the deposition region to accelerate oxidation of the metallic binder material during cold spray deposition. This accelerated oxidation enhances ceramic particle retention by creating oxide bridges and strong interfacial bonding between metal and ceramic phases
Data Source
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AI summary
A process of fabricating a thermal barrier coating is disclosed. The process includes cold spraying a substrate (101) with a feedstock (402) to form a thermal barrier coating (102) and concurrently oxidizing one or more of the substrate (101), the feedstock (402), and the thermal barrier coating (102). The cold spraying is in a region (103) having an oxygen concentration of at least 10%. In another embodiment, the process includes heating a feedstock (402) with a laser (411) and cold spraying a substrate (101) with the feedstock (402) to form a thermal barrier coating (102). At least a portion of the feedstock (402) is retained in the thermal barrier coating (102). In another embodiment, the process of fabricating a thermal barrier coating includes heating a substrate (101) with a laser (411) and cold spraying the substrate with a feedstock to form a thermal barrier coating.