Variable Density Abradable Coating for Turbine Clearance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional abradable coatings used in turbomachines, especially high-pressure turbines, face premature erosion due to extreme physico-chemical conditions, leading to reduced performance and integrity issues when in contact with the stator, as they are not effectively abradable and protective simultaneously.
Innovation Solution
A process for manufacturing an abradable coating with variable density by using a substrate with distinct portions, where different precursor materials and sintering conditions are applied to achieve varying porosity and density, allowing for localized adjustment to enhance erosion resistance and abradability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal barrier coating of high density is provided on the turbine ring, then the ring is protected against erosion and corrosion, but the coating cannot be effectively abraded and the clearance between rotor and stator increases
Solution Approach 1:
The patent applies local quality by creating a coating with spatially varying density: a first portion with high density for erosion/corrosion protection and a second portion with low density for abradability. This allows different regions of the coating to perform different functions simultaneously, resolving the contradiction between protection and abradability.
Solution Approach 2:
The patent uses composite materials by combining precursor materials with different properties (different particle sizes, shapes, and densities) to create a coating that exhibits both high-density protective characteristics and low-density abradable characteristics in different regions, resolving the contradiction through material composition variation.
2Ease of operation
If conventional abradable materials are used in high-pressure turbines, then the coating can be abraded to maintain clearance, but the coating suffers premature erosion due to extreme physico-chemical conditions
Solution Approach 1:
The patent applies local quality by creating a coating with spatially varying density: a first portion with high density for erosion/corrosion protection and a second portion with low density for abradability. This allows different regions of the coating to perform different functions simultaneously, resolving the contradiction between protection and abradability.
Solution Approach 2:
The patent uses composite materials by combining precursor materials with different properties (different particle sizes, shapes, and densities) to create a coating that exhibits both high-density protective characteristics and low-density abradable characteristics in different regions, resolving the contradiction through material composition variation.
3Reliability
If a greater clearance is provided between rotor and stator to ensure blade integrity, then blade damage is prevented, but the leakage rate increases and turbine performance decreases
Solution Approach 1:
The patent applies parameter changes by varying the density parameter of the coating material across different regions. The low-density second portion enables effective abradability to maintain minimal clearance, while the high-density first portion provides protection, thereby maintaining both blade integrity and optimal turbine performance through controlled parameter variation.
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 process enables the creation of coatings with tailored properties, providing high density for erosion protection and low density for easy abrasion, thereby maintaining turbine performance and integrity while reducing leakage.
Implementation Method 1
compression of the first precursor material between the substrate and a first support surface
Implementation Method 2
sintering of the first precursor material thus compressed to obtain a first portion of abradable coating
Data Source
Figure 1~3C
Figure 3D~3G
Figure 4A~4E
AI summary
Disclosed are a method for manufacturing an abradable coating having variable densities and an abradable coating of said type having variable densities. According to the invention, the method involves the following steps: providing a substrate (32) that has a first portion (33) and a second portion (34); applying a first precursor material to the first portion (33) of the substrate (32); compressing the first precursor material between the substrate (32) and a first support surface; sintering the compressed first precursor material so as to obtain a first abradable coating area (36a) which faces the first portion (33) of the substrate (32) and has a first density; applying a second precursor material to the second portion (34) of the substrate (32); compressing the second precursor material between the substrate (32) and a second support surface; sintering the compressed second precursor material so as to obtain a second abradable coating area (36b) which faces the second portion (33) of the substrate (32) and has a second density that differs from the first density.