Strain-Tolerant Coating with Dense Columnar Structures
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Solution Overview
Problem
Existing liquid carrier plasma spray techniques for forming coatings with columnar structures compromise durability and toughness while attempting to increase coating density, as higher density leads to loss of strain-tolerant structures.
Innovation Solution
A method involving the simultaneous deposition of two suspension feedstocks with different materials, one capable of filling nanopores, to form dense columnar structures with porosity less than four percent, maintaining strain tolerance and improving durability and toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid carrier plasma spray techniques are used to increase coating density, then coating durability is improved, but strain tolerance is compromised due to loss of columnar structures
Solution Approach 1:
The invention changes the material composition parameter by incorporating a second material with higher melting point and lower surface tension that fills nanopores within columnar structures. This allows achieving porosity below 4% while preserving the columnar morphology, thus improving durability without sacrificing strain tolerance
Solution Approach 2:
The invention uses composite materials by combining a conventional coating material with a second material (such as gadolinium aluminate or hafnium oxide) that has complementary properties. The second material fills the nanopores and stabilizes the columnar structure, creating a composite that simultaneously achieves high density and strain tolerance
2Reliability
If spray parameters are modified to increase coating density, then durability is improved, but columnar structures are lost due to uniform deposition
Solution Approach 1:
Rather than modifying spray parameters that would uniformize deposition, the invention changes the material parameters (composition, melting point, surface tension) to enable pore filling while maintaining the preferential accumulation mechanism that creates columnar structures
Solution Approach 2:
The second material selectively fills nanopores within columnar regions while leaving inter-columnar gaps intact. This local quality change densifies the coating matrix without affecting the overall columnar morphology or the strain-tolerant gap structure
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 method enhances coating durability and toughness while maintaining strain tolerance by increasing material density and preserving columnar structures, applicable beyond thermal barrier coatings.
Implementation Method 1
liquid carrier plasma spray techniques
Implementation Method 2
The columnar structures are formed during material deposition by preferential material accumulation on surface asperities on a substrate
Implementation Method 3
The first suspension has particles of a first material suspended in a liquid medium. The second suspension has particles of a second material, different from the first material, suspended in a liquid medium
Data Source
AI summary
A strain-tolerant coating for use in gas turbine engines can include a plurality of dense, generally vertically-oriented columnar structures formed during deposition by preferential material accumulation, and a plurality of inter-columnar gaps separating the columnar structures. The columnar structures can include a plurality of randomly-oriented particle splats and can have a porosity of less than four percent.