PS-PVD Thermal Barrier Coating with Columnar Microstructure
Solution Overview
Problem
Conventional thermal barrier coating methods, such as EB-PVD, are costly and inefficient due to high plant costs and low application speed, while existing plasma spray processes result in coatings with low stretch tolerance and adhesive strength under cyclic thermal strain.
Innovation Solution
A method using plasma spray physical vapor deposition (PS-PVD) with a two-step powder feed rate adjustment to achieve a thermal barrier coating with a columnar structure, where the initial low feed rate ensures high vaporization and bonding as mixed phases, followed by a higher feed rate for elongate column formation, enhancing adhesive strength and stretch tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EB-PVD is used to apply thermal barrier coating, then adhesive strength and stretch tolerance are improved, but plant costs increase and application speed decreases
Solution Approach 1:
The patent changes the process parameters by using plasma spray physical vapor deposition instead of electron beam physical vapor deposition, operating at lower costs with improved application speed while maintaining columnar microstructure formation through controlled powder feed rates and plasma conditions to achieve comparable adhesive strength and stretch tolerance
Solution Approach 2:
The patent replaces the electron beam heating system with a plasma spray system that uses plasma to heat and deposit coating material, substituting a different physical mechanism (plasma heating vs. electron beam heating) to achieve the same coating effect with improved efficiency
2Productivity
If plasma spray is used to apply thermal barrier coating, then costs are reduced and application speed increases, but stretch tolerance and adhesive strength deteriorate
Solution Approach 1:
The patent optimizes plasma spray parameters by controlling powder feed rate to achieve optimal vaporization and columnar microstructure formation, adjusting plasma power, pressure, and coating thickness to maintain high stretch tolerance and adhesive strength while preserving the cost and speed advantages of plasma spray
Solution Approach 2:
The patent creates local quality variations in the coating microstructure by forming elongate columns perpendicular to the substrate surface with mixed phases at the coating-substrate interface, providing enhanced adhesive strength and stretch tolerance in specific regions while maintaining overall coating performance
3Productivity
If atmospheric plasma spraying is used to apply thermal barrier coating, then application speed increases, but stretch tolerance deteriorates due to lamellar layer formation
Solution Approach 1:
The patent changes the plasma spray parameters by operating at lower powder feed rates initially to achieve complete vaporization and columnar microstructure formation, then increasing feed rate to maintain application speed, thereby preventing lamellar layer formation and ensuring high stretch tolerance
Solution Approach 2:
The patent uses periodic adjustment of powder feed rate during the coating application process, initially using low feed rate for columnar structure formation and then increasing to higher feed rate for efficient coating deposition, maintaining both stretch tolerance and application speed throughout the 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
The method reduces costs and improves the adhesive strength and cyclic thermal strain resistance of thermal barrier coatings, making them comparable to EB-PVD coatings but more economically viable and efficient.
Implementation Method 1
a ceramic coating material is applied to the substrate surface by means of plasma spray physical vapor deposition, with the coating material being injected into the plasma jet as a powder and being partly or completely vaporized there
Implementation Method 2
the coating material being injected into the plasma jet as a powder and being partly or completely vaporized there
Implementation Method 3
a plasma jet is generated, for example, in that a plasma gas is conducted through the plasma torch and is heated therein
Implementation Method 4
the coating material melted on solidifies at the substrate surface
Data Source
AI summary
To apply a thermal barrier coating (10), a plasma jet (5) is generated by a plasma torch in a work chamber (2) and is directed to the surface of a substrate (3) introduced into the work chamber, and a ceramic coating material is applied to the substrate surface by means of PS-PVD, wherein the coating material is injected into the plasma jet as a powder and is partly or completely vaporized there. On applying the thermal barrier coating, in a first workstep the feed rate of the injected powder is set so that a large part of the injected powder vaporizes, wherein the coating material condenses from the vapor phase on the substrate surface and forms mixed phases with the material of the substrate surface. In a second workstep, the feed rate of the injected powder it increased by at least a factor of 5, whereby the portion of the powder which vaporizes is reduced and the coating material is deposited in the form of elongate columns which form an anisotropic microstructure and which are aligned substantially perpendicular to the substrate surface.