Geometrically Segmented Abradable Ceramic Coating Spallation Resistance

Solution Overview

Problem

Geometrically segmented abradable ceramic (GSAC) coatings used in high-temperature applications, such as gas turbine engine components, are prone to spallation at inter-segment edges due to crack formation from sintering shrinkage stresses, despite demonstrating improved durability and temperature resistance over conventional thermal barrier coatings.

Innovation Solution

A multi-layered ceramic topcoat with varying hardness is applied to a geometrically segmented substrate, featuring a bond coat and layers with specific hardness profiles and thicknesses, where the harder layers are deposited in high-stress areas and the softer layers are thicker to provide toughness and resistance, and the coating is machined to create a smooth surface, with denser layers positioned at divot bottoms and the surface to reduce stress and spallation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a geometrically segmented abradable ceramic coating is used to protect turbine components from erosion and oxidation, then the component durability and temperature resistance are improved, but spallation occurs at inter-segment edges due to crack formation from sintering shrinkage stresses

Engineering Contradiction:

Improvecomponent durabilityVSAvoidspallation resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by creating a geometrically segmented surface with divots at specific locations where spallation is most likely to occur. The coating structure varies locally with harder material phases positioned at the divot locations and inter-segment edges, while softer phases are positioned in the valleys between segments. This local differentiation of material properties addresses the spallation problem at critical locations without compromising the overall protective function of the coating.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining multiple ceramic phases with different hardness and toughness properties within the coating structure. The coating includes a mixture of hard phases (such as alumina or silica) and softer, more ductile phases (such as mullite or glassy phases). This composite structure allows the coating to simultaneously provide erosion resistance from the hard phases and spallation resistance from the tougher phases, particularly at the geometric segments and inter-segment edges where stress concentrations occur.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If the ceramic topcoat is made harder to resist erosion, then the protective capability is improved, but the coating becomes more susceptible to cracking and spallation under thermal stress

Engineering Contradiction:

Improveerosion resistanceVSAvoidcrack resistance

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies local quality by creating a geometrically segmented surface with divots at specific locations where spallation is most likely to occur. The coating structure varies locally with harder material phases positioned at the divot locations and inter-segment edges, while softer phases are positioned in the valleys between segments. This local differentiation of material properties addresses the spallation problem at critical locations without compromising the overall protective function of the coating.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining multiple ceramic phases with different hardness and toughness properties within the coating structure. The coating includes a mixture of hard phases (such as alumina or silica) and softer, more ductile phases (such as mullite or glassy phases). This composite structure allows the coating to simultaneously provide erosion resistance from the hard phases and spallation resistance from the tougher phases, particularly at the geometric segments and inter-segment edges where stress concentrations occur.

Inventive Principle:

Principle #40Composite materials

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 enhances spallation resistance by distributing stress and reducing cracking, maintaining component durability and efficiency in high-temperature environments, thereby extending the lifespan of turbine components and reducing maintenance needs.

Implementation Method 1

The solution effectively enhances spallation resistance by distributing stress and reducing cracking

Methodology Applied

Scientific EffectStress distribution:

Implementation Method 2

A multi-layered ceramic topcoat with varying hardness is applied to a geometrically segmented substrate

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS11319829B2Geometrically segmented abradable ceramic thermal barrier coating with improved spallation resistance

Publication Date: 2022.05.03 RTX CORP

AI summary

A turbine article includes a substrate with a geometric surface having a multiple of divots recessed into the substrate, and a ceramic topcoat disposed over the geometric surface, the topcoat including at least a first layer having a first hardness and a second layer having a second hardness, the first hardness different than the second hardness.