Superlattice Bond Layer Thermal Barrier Coating for Titanium
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Solution Overview
Problem
Current thermal barrier coatings (TBCs) are not compatible with titanium-based alloys, limiting their use in hypersonic applications due to poor high-temperature oxidation resistance, which constrains velocity, range, and maneuverability of hypersonic missiles and vehicles.
Innovation Solution
A thermal barrier coating system comprising a bond layer with a superlattice structure, an insulating layer of Yttria stabilized Zirconia, and a sealant layer of hexagonal boron nitride or aluminum nitride is developed, specifically designed for titanium-based substrates to enhance oxidation resistance and thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If titanium-based alloys are used for hypersonic missile components, then weight is reduced and maneuverability is improved, but high-temperature oxidation resistance deteriorates
Solution Approach 1:
The patent applies composite materials by creating a multi-layer thermal barrier coating system consisting of a bond layer (MCrAlY or MCrCoAl), an insulating layer (YSZ), and a sealant layer. This composite structure combines materials with complementary properties: the bond layer provides oxidation resistance, the insulating layer provides thermal protection, and the sealant layer provides environmental sealing, collectively enabling titanium alloys to withstand hypersonic operating temperatures while maintaining weight advantages
Solution Approach 2:
The thermal barrier coating system acts as an intermediary between the titanium-based alloy substrate and the harsh hypersonic environment. The bond layer specifically serves as an intermediary that chemically bonds to both the titanium substrate and the insulating YSZ layer, transferring and distributing thermal and mechanical stresses while providing the first line of oxidation protection
2Temperature
If conventional TBC systems (MCrAlY/YSZ) are applied to titanium alloys, then thermal protection is provided, but compatibility deteriorates due to poor adhesion and oxidation resistance
Solution Approach 1:
The patent applies parameter changes by modifying the bond layer composition from conventional MCrAlY to include cobalt and aluminum (MCrCoAl), and by optimizing the thickness parameters of each layer. The bond layer is designed with specific compositional parameters (at least 5 wt% Cr, at least 5 wt% Al, and Co content) to achieve both adhesion to titanium and protection against oxidation, while the insulating layer thickness is optimized to provide adequate thermal protection without excessive weight
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different layers of the coating system. The bond layer is specifically designed with oxidation-resistant composition and properties for interfacing with the titanium substrate, the insulating layer is designed with low thermal conductivity for heat barrier function, and the sealant layer is designed for environmental sealing. Each layer has locally optimized properties tailored to its specific function within the overall system
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 provides improved oxidation resistance and thermal shock resistance, allowing titanium-based substrates to operate at elevated temperatures up to 1000°C for extended periods, thereby enhancing the performance and range of hypersonic aerospace devices.
Implementation Method 1
The insulating layer may be disposed on the bond layer, may include from about 7 to about 8 percent by weight of Yttria stabilized Zirconia (YSZ), and may have a thickness of about 30 μm
Implementation Method 2
The sealant layer may be disposed on the insulating layer, may include hexagonal boron nitride (hBN) and/or aluminum nitride (AlN)
Data Source
AI summary
Thermal barrier coatings for substrates comprising titanium. The thermal barrier coating may include a bond layer, an insulating layer, and a sealant layer. The bond layer may include titanium, a titanium alloy, an intermetallic compound of titanium, and/or a titanium metal matrix composite. The bond layer may have a superlattice structure having a periodically repeating group of layers. Methods for producing the thermal barrier coatings and articles of manufacture employing the thermal barrier coatings.