Low Porosity Abradable Coating for Gas Turbine Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-temperature mechanical systems, such as gas turbine engines, face challenges with abradable coatings that are prone to degradation from high porosity, leading to increased susceptibility to environmental attacks and reduced efficiency due to leakage and mechanical wear.
Innovation Solution
A dense abradable coating is developed using a rare earth silicate and a dislocator phase, which includes materials like hafnium diboride and tantalum carbide, to reduce porosity and enhance durability while maintaining abradability, thereby providing a physical barrier against environmental species and improving thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional abradable coating is used to reduce clearance gap, then sealing efficiency is improved, but porosity increases leading to susceptibility to environmental degradation
Solution Approach 1:
The patent applies composite materials by combining rare earth silicate base coating with dislocator phase particles (such as tungsten carbide, tantalum carbide, or hafnium diboride) to create a multi-phase abradable coating. This composite structure provides both the porosity needed for abradability and the dense phase regions that resist environmental degradation, resolving the contradiction between sealing efficiency and susceptibility to harmful factors.
Solution Approach 2:
The dislocator phase creates local regions of high density and chemical stability within the coating structure, while the rare earth silicate matrix maintains overall porosity for abradability. This local quality differentiation allows different regions of the coating to perform different functions: the matrix provides abradability for sealing, while the dislocator phase regions provide resistance to environmental attack.
2Adaptability or versatility
If porosity is increased to maintain abradability, then coating compliance is improved, but resistance to chemical ingress deteriorates
Solution Approach 1:
The dislocator phase acts as an intermediary barrier within the coating structure. It provides a dense, chemically stable phase that mediates between the porous matrix (which allows compliance and abradability) and the external environment (which causes chemical degradation). The dislocator phase particles create tortuous paths and physical barriers that hinder chemical ingress while maintaining overall coating compliance.
3Reliability
If coating density is increased to reduce environmental attack, then durability is improved, but abradability deteriorates
Solution Approach 1:
The coating is segmented into distinct phases: a rare earth silicate matrix that provides porosity and abradability, and dispersed dislocator phase particles that provide density and durability. This segmentation allows each phase to perform its specialized function without compromising the other, enabling the coating to be both durable and abradable.
Solution Approach 2:
By creating a composite material with specific phase distribution and morphology, the patent achieves both durability and abradability. The rare earth silicate matrix maintains porosity for easy abrasion, while the embedded dislocator phase particles provide structural integrity and resistance to environmental attack, resolving the contradiction between durability and abradability.
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 dense abradable coating effectively reduces porosity, enhances thermal resistance, and maintains abrasion characteristics, leading to improved efficiency and extended lifespan of high-temperature mechanical components by preventing ingress of deleterious compounds and reducing mechanical wear.
Implementation Method 1
The dense abradable coating may include a dislocator phase, which facilitates the use of a higher density/lower porosity abradable coating... provides a physical barrier against environmental species
Implementation Method 2
As the turbine blade rotates, the tip of the turbine blade contacts the abradable coating and wears away a portion of the coating to form a groove in the abradable coating corresponding to the path of the turbine blade
Data Source
AI summary
An article for use in a high-temperature environment that includes a substrate including a superalloy material, a ceramic, or a ceramic matrix composite, and an abradable coating on the substrate, the abradable coating including a rare earth silicate and a dislocator phase, the dislocator phase forms one or more distinct phase regions in the abradable coating and comprises at least one of hafnium diboride (HfB2), zirconium diboride (ZrB2), tantalum nitride (TaN or Ta2N), tantalum carbide (Ta2C), titanium diboride (TiB2), zirconium carbide (ZrC), hafnium carbide (HfC), tantalum diboride (TaB2), hafnium nitride (HfN), or niobium carbide (NbC).