Online Thermal Spraying Control for Turbine Coating Hardness
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Solution Overview
Problem
Current methods for producing run-in spray coatings for turbine engine components, particularly using SM2042 powder, face instability due to an unpredictable injection process, leading to inconsistent hardness and high rework rates, as the hardness can only be measured post-process, causing delays and changes in spraying conditions.
Innovation Solution
Implementing an online process control system with a PFI unit and/or optical spectrometer to monitor and regulate thermal spraying by calculating specific process parameters, such as Δx from luminance distribution, allowing for real-time adjustment of primary and secondary gas flows and distance between the component and burner, ensuring reproducible low-hardness coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal spraying is performed without online monitoring, then the coating can be applied, but the hardness becomes inconsistent and rework rates increase
Solution Approach 1:
The patent implements an online monitoring system using PFI (Particle Flux Imaging) and optical spectrometry that continuously measures coating properties during the thermal spraying process. This feedback mechanism allows real-time detection of hardness variations and process deviations, enabling immediate adjustments to spraying parameters to maintain consistent coating quality and reduce rework rates
Solution Approach 2:
The patent replaces traditional post-process mechanical hardness testing with non-contact optical measurement methods (PFI and spectrometry). This substitution enables continuous online monitoring without interrupting the spraying process, providing real-time data on coating properties while eliminating the delays and condition changes associated with batch testing
2Measurement precision
If hardness is measured only after the spraying process, then measurement can be performed, but process delays occur and spraying conditions may change
Solution Approach 1:
The patent performs hardness measurement and process evaluation during the spraying operation itself rather than after completion. The online monitoring system continuously assesses coating properties in real-time, allowing immediate detection and correction of deviations before they affect the entire coating batch, thereby eliminating post-process waiting time and preventing condition changes
Solution Approach 2:
The patent maintains continuous monitoring and measurement throughout the entire spraying process without interruption. The PFI and optical spectrometry systems operate concurrently with the thermal spraying, ensuring that measurement activities do not pause or delay the coating application, thereby maintaining continuous productive action while providing real-time quality data
3Device complexity
If the injection process is not monitored, then the process is simpler, but the spraying conditions become unpredictable and quality inconsistent
Solution Approach 1:
The patent monitors and adjusts multiple spraying parameters including powder feed rate, gas flow rates, and torch-to-substrate distance in real-time. By continuously measuring these parameters and their effects on coating properties, the system can dynamically adjust settings to maintain optimal conditions, transforming an unpredictable process into a controlled one with consistent quality outcomes
Solution Approach 2:
The online monitoring system serves multiple functions simultaneously: it measures coating hardness, monitors spray particle characteristics, evaluates process stability, and provides feedback for parameter adjustment. This multi-functional approach consolidates what would otherwise require separate measurement and control systems, managing complexity through integration while comprehensively ensuring coating quality
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
Enables reliable and reproducible production of run-in coatings with reduced rework rates and minimal delays, maintaining quality despite process deviations, by allowing continuous monitoring and adjustment of spraying conditions.
Implementation Method 1
at least one process parameter which influences the quality of the sprayed layer and is responsible for the formation of the layer and its properties is recorded, evaluated and controlled by means of an optical spectroscopy arrangement
Implementation Method 2
EP 1 332 799 A1 describes a device and a method for thermal spraying, in which a partially melted or melted additional material is guided onto a substrate surface to be coated using a gas or gas mixture
Data Source
AI summary
Disclosed is a method for producing a spray coating, particularly an abradable spray coating for parts of a turbine engine by means of a thermal spraying process. An online process monitoring system, especially a PFI unit and/or a spectrometer unit, is provided for monitoring and regulating the thermal spraying process. In the disclosed method, at least one process parameter is calculated according to formula PB1 = PB2 + HB1 - HB2 - (?x y)/z + n, wherein PB1 is the process parameter of the part that is to be coated, pB2 is the process parameter of a previous coating, HB1 is the hardness of the spray coating that is to be coated, HB2 is the hardness of the previous spray coating, ?x is a process variable of the online process monitoring system, and y, z, and n are constant parameters.