Abradable Ceramic Coating with Low-Temperature Reactive Sintering
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Solution Overview
Problem
Existing abradable seals in gas turbines face challenges in achieving a balance between high abradability and erosion resistance, with current methods either compromising on one or the other, and often requiring high-temperature sintering processes that are energy-intensive and complex.
Innovation Solution
A method involving a pulverulent composition of a matrix powder and ceramic filler hydrated precursor powder, compressed at high pressure and sintered at low temperatures below 550°C, resulting in a ceramic composite coating with optimized porosity and microhardness for improved abradability and erosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal spraying is used to form a protective coating on ring sectors, then the coating provides thermal barrier protection against high temperatures and erosion, but the coating has low abradability leading to blade tip wear
Solution Approach 1:
The invention changes the microstructural parameters of the thermal barrier coating by controlling porosity (10-40%) and incorporating specific ceramic particles with defined size distributions and aspect ratios. These parameter changes enable the coating to exhibit both thermal barrier properties and controlled abradability, allowing it to wear smoothly under blade contact while maintaining protective functions.
Solution Approach 2:
The invention uses composite materials consisting of a matrix phase (e.g., yttria-stabilized zirconia) combined with dispersed ceramic particles of different sizes and shapes. This composite structure provides both the thermal barrier protection needed for high-temperature resistance and the abradability required for smooth wear characteristics, resolving the contradiction between protection and manufacturability.
2Ease of manufacture
If porogenic agents are incorporated to increase porosity rate of the barrier, then the abradability of the coating is improved, but the erosion resistance and service life of the barrier are significantly degraded
Solution Approach 1:
The invention applies local quality by creating a non-uniform distribution of porosity and ceramic particles within the coating structure. The porosity is controlled to be sufficient for abradability (10-40%) but distributed in a way that maintains erosion resistance in critical areas. The presence of ceramic particles with specific aspect ratios (≥2) provides localized reinforcement that enhances erosion resistance while the overall porosity structure maintains abradability.
Solution Approach 2:
The invention utilizes porous materials with controlled porosity (10-40%) to achieve abradability while maintaining erosion resistance. The porous structure allows the coating to wear smoothly under blade contact, while the specific pore distribution and ceramic particle reinforcement prevent excessive material loss and maintain structural integrity during service.
3Reliability
If flash sintering or solid-state sintering is used to produce abradable coatings with property gradients, then good abradability and erosion resistance are achieved, but special substrate preparation is required and temperatures above 1000°C are needed
Solution Approach 1:
The invention changes the sintering temperature parameter from conventional high temperatures (>1000°C) to a lower range (500-1200°C), which simplifies the overall process while still achieving the desired coating properties. This parameter change, combined with controlled porosity and ceramic particle incorporation, allows the coating to develop both abradability and erosion resistance without requiring complex substrate preparation or extreme processing conditions.
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 produces a coating with enhanced abradability and erosion resistance, allowing for reduced wear and extended service life, while being more energy-efficient and less thermally stressful on the substrate.
Implementation Method 1
a step of reactive sintering of the obtained pulverulent composition, during which the compression is maintained, at a temperature of less than 550° C.
Implementation Method 2
In this disclosure, the term 'reactive sintering' refers to sintering in which the sintered material undergoes a chemical reaction. Typically, the sintered material may undergo dehydration.
Implementation Method 3
compressing the obtained pulverulent composition at a pressure greater than 150 MPa
Data Source
AI summary
A method for producing an abradable ceramic composite coating on a substrate, the method including: obtaining a pulverulent composition including a matrix powder and a ceramic filler hydrated precursor powder having a lamellar crystallographic structure, wherein the ceramic filler powder represents from 5 to 40% of the combined volume of the matrix powder and the ceramic filler powder, compressing the prepared pulverulent composition at a pressure greater than 150 MPa, and a step of reactive sintering the obtained pulverulent composition, during which the compression is maintained, at a temperature of less than 550° C., and the particles of the matrix powder in the sintered pulverulent composition have an aspect ratio of 2 or greater.