Abradable Turbine Ring Layer via Spark Plasma Sintering
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Solution Overview
Problem
High-pressure turbines in turbomachines face premature erosion of conventional abradable tracks due to extreme physico-chemical conditions, leading to reduced performance and integrity issues when coated thermal barriers are damaged.
Innovation Solution
The method involves using cobalt- or nickel-based metal powders for sintering abradable plates via Spark Plasma Sintering (SPS), with a fluxing element to reduce sintering temperature and a chemically inert insert to control dimensions and prevent sticking, allowing for dual functionality as both abradable and heat shields, and facilitating brazing for repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal barrier coating is applied to protect the turbine ring, then protection against erosion and corrosion is improved, but the coating's high density prevents effective abrasion and blade integrity is compromised
Solution Approach 1:
The invention changes the material parameters by using cobalt- or nickel-based metal powders with specific compositional ranges (e.g., CoNiCrAlY superalloys) that provide both thermal barrier properties and controlled abrasiveness. The chemical composition is optimized to balance protection and abrasion characteristics
Solution Approach 2:
The invention uses composite material structures where cobalt- or nickel-based metal powders are combined with other elements to create a multi-functional coating that simultaneously provides thermal protection and controlled abrasion. The composite nature allows tuning of both protective and abrasive properties
2Manufacturing precision
If conventional abradable tracks are used in high-pressure turbines, then clearance control is improved, but premature erosion occurs due to extreme physico-chemical conditions
Solution Approach 1:
The invention changes the material parameters by selecting cobalt- or nickel-based powders with high-temperature resistance and specific chemical compositions that are resistant to erosion and corrosion in extreme conditions, while maintaining the necessary abrasion properties for clearance control
Solution Approach 2:
The invention employs composite materials with enhanced thermal and chemical stability that can withstand the extreme physico-chemical conditions in high-pressure turbines while preserving the abradable characteristics needed for precise clearance control
3Productivity
If SPS sintering is used to form abradable layers, then production time is reduced and material versatility is improved, but precise control of layer dimensions and shrinkage is required
Solution Approach 1:
The invention applies preliminary action by carefully preparing and compacting the metal powder layers before SPS sintering to establish precise initial dimensions. The powder is deposited in controlled layers with specific thicknesses and densities, and chemically inert inserts are pre-positioned to define boundaries, ensuring that the rapid SPS process produces layers with accurate final dimensions
Solution Approach 2:
The invention uses chemically inert inserts as intermediaries during the SPS sintering process. These inserts are placed between powder layers to prevent sticking and to act as spacers that control the thickness and dimensions of the sintered layers, enabling precise dimensional control during the rapid heating process
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
This approach provides durable abradable layers that maintain performance and integrity by reducing erosion and corrosion, while allowing for easy repair and minimizing discontinuities, thus enhancing the turbine's operational efficiency and longevity.
Implementation Method 1
Spark Plasma Sintering (SPS), also known as Field Assisted Sintering Technology (FAST) or flash sintering, is a sintering process in which a powder is simultaneously subjected to a high-intensity pulsed current and uniaxial pressure to form a sintered material
Implementation Method 2
Powder based on a fluxing element allows the sintering temperature of the powder mixture to be reduced
Implementation Method 3
At least two layers of the powder mixture are deposited in the mold, the two layers being separated from each other by a chemically inert insert
Implementation Method 4
since SPS sintering is performed under uniaxial pressure exerted by the mold on the powder layer, the shrinkage due to sintering the powder layer to form the abradable plate is limited to the direction of pressure application
Data Source
Figure 1~4
Figure 5A~7B
AI summary
The invention relates to a method for manufacturing an abradable plate (32) for a turbine shroud (24, 26) of a turbomachine, said method involving preparing a mixture comprising a cobalt- or nickel-based metal powder and a powder based on a melting element, depositing a layer of the powder mixture in a mold, and creating the abradable plate (32) by spark plasma sintering the layer of the powder mixture. The invention also relates to a method for repairing a turbine shroud (24, 26) for a turbomachine.