Thermal Spray Powder Sintering for Crack Reduction
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Solution Overview
Problem
The reusing method for thermal spray powders containing mixtures of different rare-earth oxides as additive agents in ceramic layers results in lower thermal cycle properties due to insufficient mixing and crack formation, which is a challenge in high-temperature applications like gas turbines.
Innovation Solution
A method involving the preparation of a powder mixture with zirconia-based ceramic particles containing different rare-earth oxides, where each particle has a cumulative particle diameter of 0-10 μm, and secondary particles are produced by sintering these particles to create a finely dispersed ceramic layer, reducing the formation of large chunks and cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If recovered ceramic spray powder containing different rare-earth oxides is reused directly, then production cost is reduced, but thermal cycle properties deteriorate due to insufficient mixing and crack formation
Solution Approach 1:
The recovered powder particles are crushed into smaller segments (10% cumulative particle diameter of 0-10 μm) to create finer particles that can be more uniformly mixed. This segmentation prevents the formation of large chunks with insufficient mixing and reduces crack formation during thermal cycling.
Solution Approach 2:
The powder mixture is prepared in advance by crushing recovered particles and mixing them with fresh powder before spraying. This preliminary mixing action ensures uniform distribution of different rare-earth oxide particles, preventing segregation and ensuring consistent thermal cycle properties in the deposited coating.
2Loss of substance
If large particle size recovered powder is reused, then material cost is reduced, but mixing uniformity deteriorates leading to crack formation
Solution Approach 1:
The particle size parameter is changed by crushing recovered powder to achieve a 10% cumulative particle diameter of 0-10 μm. This parameter change improves flowability and mixing uniformity while maintaining material reuse benefits, preventing the formation of large chunks that cause cracking.
3Adaptability or versatility
If different rare-earth oxide particles are mixed in recovered powder, then material versatility is improved, but particle size distribution becomes uneven causing cracks
Solution Approach 1:
Recovered powder particles containing different rare-earth oxides are crushed into uniform fine segments. This segmentation creates a consistent particle size distribution (10% cumulative diameter of 0-10 μm) that maintains the versatility of using different rare-earth oxides while eliminating the particle size unevenness that causes cracking.
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 enhances the thermal cycle properties of the ceramic layer, improving durability and reliability in high-temperature environments, such as those encountered in gas turbines, while also reducing material costs through powder reuse and efficient recovery processes.
Implementation Method 1
secondary particles are produced by sintering these particles
Data Source
AI summary
A method for producing a thermal spray powder includes: a preparing step of preparing a powder mixture containing a first particle made from zirconia-based ceramic containing a first additive agent and a second particle made from zirconia-based ceramic containing a second additive agent, the powder mixture having a 10% cumulative particle diameter of more than 0 μm and not more than 10 μm; and a secondary-particle producing step of producing a plurality of secondary particles each of which includes the first particle and the second particle sintered with each other.