High-Entropy Thermal Barrier Coating for Engine Temperature Limits
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Solution Overview
Problem
Current thermal barrier coatings, such as YSZ, have a service temperature limit of around 1200 °C and suffer from volume expansion and phase transition issues during cooling, leading to coating failure. Additionally, they have high thermal conductivity and inadequate high-temperature phase stability.
Innovation Solution
A lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating with a chemical molecular formula of La0.4Gd0.4Sm0.4A0.4B0.4Zr2O7 is developed, where A and B are different rare earth elements. This coating is prepared using a high-temperature solid-state method followed by electron beam physical vapor deposition, resulting in a unique columnar crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If YSZ thermal barrier coating is used, then thermal barrier protection is provided, but service temperature is limited to 1200°C and phase transition occurs during cooling
Solution Approach 1:
The patent uses a composite material system comprising lanthanum-gadolinium-samarium-based high-entropy ceramic as the thermal barrier coating layer and NiCoCrAlYHf as the alloy substrate. This composite structure combines the high-temperature stability of the ceramic coating with the high strength and oxidation resistance of the alloy substrate, enabling service temperatures above 1200°C while maintaining phase stability through the specific composition and microstructure design of the high-entropy ceramic system.
2Reliability
If traditional thermal barrier coating is used, then coating protection is provided, but thermal conductivity is high and service life is short
Solution Approach 1:
The patent changes the compositional parameters by introducing high-entropy ceramic material with specific rare earth element combinations (lanthanum-gadolinium-samarium-based system) and controlling the stoichiometry to achieve optimal thermal insulation properties. The high-entropy ceramic coating exhibits lower thermal conductivity and improved thermal stability, extending service life while reducing energy loss through the coating layer.
3Productivity
If high-temperature operation is implemented, then engine efficiency is improved, but coating failure occurs due to volume expansion
Solution Approach 1:
The patent addresses thermal expansion issues by selecting and optimizing the thermal expansion coefficient of the high-entropy ceramic coating to match that of the NiCoCrAlYHf alloy substrate. This thermal expansion matching minimizes the coefficient of thermal expansion mismatch, reducing thermal stress and volume expansion differences during temperature cycling, thereby preventing coating failure while enabling high-temperature operation for improved engine efficiency.
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 lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating exhibits improved high-temperature phase stability, reduced thermal conductivity, and enhanced thermal expansion coefficient, leading to increased service life and better thermal cycling performance compared to traditional YSZ coatings.
Implementation Method 1
mounting the lanthanum-gadolinium-samarium-based high-entropy target material into an electron beam physical vapor deposition device, and preparing the lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating on the NiCoCrAlYHf bottom layer by electron beam evaporation of the lanthanum-gadolinium-samarium-based high-entropy target material
Implementation Method 2
synthesizing a lanthanum-gadolinium-samarium-based high-entropy target material by a high-temperature solid-state method at a synthesis temperature of 2,000 °C to 2,200 °C
Data Source
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AI summary
The invention belongs to the technical field of aeronautical engine thermal barrier coatings and relates to a lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating material and a preparation method therefor. The lanthanum-gadolinium-samarium-based high-entropy target material has a molecular formula of La0.4Gd0.4Sm0.4A0.4B0.4Zr2O7, where A and B are different rare earth elements. The following deposition process parameters are selected: a vacuum degree of a deposition chamber of less than 5 × 10-4 Torr; a beam intensity of electron beam of 1.6 A to 1.8 A; a temperature of the sample of 1,000 °C to 1,050 °C; an evaporation time of 30 min to 60 min; and ultimately a lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating is obtained on the rotating sample. The thermal barrier coating material of the invention has a thermal expansion coefficient that is relatively close to that of YSZ and exhibits low thermal conductivity. The lanthanum-gadolinium-samarium-based high-entropy thermal barrier coatings by electron beam physical vapor deposition exhibits a unique columnar crystal structure and a long service life. The invention can not only ensure the reduction of the thermal conductivity of the coating, but also increase the service temperature of the coating, and can also remedy the practical problems of poor service life and low thermal expansion coefficient of the coating.