Thermal Barrier Coating Deposition via Pulse Modulation
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Solution Overview
Problem
Existing thermal barrier coating systems for gas turbine engines face challenges in maintaining low thermal conductivity and preventing arcing during deposition, which can lead to substrate and coating damage, while also requiring the use of inert gases that can cause electrical breakdowns.
Innovation Solution
A method and apparatus for depositing thermal barrier coatings using a system that alternates between plasma-assisted and non-plasma assisted physical vapor deposition modes, with pulse modulation of the substrate bias voltage to avoid arcing and reduce thermal conductivity, and the use of reactive gas to maintain stoichiometric ceramic deposition without inert gases, allowing for stable plasma discharge at lower pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plasma-assisted physical vapor deposition is used to deposit thermal barrier coating, then coating adhesion and microstructure modification are improved, but arcing and electrical breakdown occur during deposition
Solution Approach 1:
The patent applies periodic action by alternating between plasma-assisted deposition phases and non-plasma phases in a cyclic manner. During plasma phases, ions bombard the substrate to enhance adhesion and modify microstructure. During non-plasma phases, the system allows plasma to decay, preventing continuous arcing and electrical breakdown. This periodic switching maintains coating quality while ensuring deposition stability.
Solution Approach 2:
The patent employs dynamics by dynamically adjusting the plasma generation and substrate bias voltage parameters during the deposition process. The system transitions between plasma and non-plasma states based on real-time conditions, optimizing the balance between achieving good adhesion through ion bombardment and preventing electrical breakdown through controlled plasma decay intervals.
2Stability of the object's composition
If inert gases are used to maintain plasma discharge, then stable plasma is achieved, but electrical breakdowns occur
Solution Approach 1:
The patent extracts and eliminates inert gases from the deposition chamber atmosphere, replacing them with reactive gases (oxygen, nitrogen, carbon dioxide). This removal of inert gases prevents electrical breakdown while maintaining plasma stability through the use of reactive gas chemistry that supports plasma discharge without requiring inert atmosphere.
Solution Approach 2:
The patent changes the gas composition parameter from inert gas-based atmosphere to reactive gas-based atmosphere. This parameter change fundamentally alters the plasma discharge characteristics, enabling stable plasma to be maintained without the electrical breakdown issues associated with inert gases, while also improving coating stoichiometry and adhesion.
3Loss of energy
If alternating plasma-assisted and non-plasma deposition modes are used, then thermal conductivity is reduced, but deposition time increases
Solution Approach 1:
The patent uses periodic action with optimized cycle times to achieve low thermal conductivity coatings. By alternating between plasma and non-plasma phases in a controlled sequence, the system creates microstructural transitions that scatter phonons and reduce thermal conductivity. The periodic cycling is timed to minimize total deposition time while achieving the desired thermal performance.
Solution Approach 2:
The patent creates composite microstructures through alternating deposition modes, forming a layered or intermixed structure with different properties. The plasma-assisted layers provide enhanced adhesion and modified microstructure, while non-plasma layers provide baseline coating properties. This composite approach achieves reduced thermal conductivity through microstructural scattering while maintaining efficient deposition rates.
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 solution effectively reduces thermal conductivity and enhances TBC adhesion by preventing arcing and electrical breakdowns, while eliminating the need for inert gases, resulting in improved durability and efficiency of the thermal barrier coatings.
Implementation Method 1
An electron beam gun is positioned to direct an electron beam to a surface of the ingot for evaporating the ingot
Implementation Method 2
During PA-PVD stages, plasma ions bombard the surface of coated TBC and introduce modifications into TBC microstructure
Implementation Method 3
sharp transitions from the microstructure of one deposition mode to the microstructure of the other deposition mode strongly influence the TBC thermal conductivity due to scattering of providing thermal conductivity phonons and photons on the transitions
Data Source
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AI summary
A material is applied to a part (32). The part (32) is placed in a deposition chamber (24) and a first electric potential is applied to the part (32). Components are evaporated for forming the material. The evaporated components are ionized. The first electric potential is modulated so as to draw the ionized component to the part. The modulation comprises a plurality of first steps (50) for PA-PVD. Each of the first steps (50) comprises a series of pulses (54) of negative potential. The modulation further comprises a plurality of second steps (52) for PVD alternating with the first steps.