Gas Turbine Blade Repair for Nitride Layer Identification
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Solution Overview
Problem
Conventional methods fail to effectively identify and remove base material deterioration layers, such as nitride layers, on gas turbine blades, leading to potential cracking due to their hardness and reduced ductility, and existing repair methods may result in incomplete removal or unnecessary waste.
Innovation Solution
A method involving the removal of thermal barrier coating, electrolytic etching to identify and remove base material deterioration layers, followed by applying a new thermal barrier coating, with thickness measurements to ensure complete removal and prevent waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hollowing out method is used to remove nitride layer, then base material deterioration layer can be removed, but nitride layer may remain if not properly identified
Solution Approach 1:
The patent introduces electrolytic etching as an intermediary process between thermal barrier coating removal and nitride layer removal. This etching step reveals the macrostructure of the base material, making the nitride layer visible and identifiable. The etching solution acts as a mediator that highlights the deterioration layer without removing it completely, enabling precise identification before final removal.
Solution Approach 2:
The patent performs electrolytic etching as a preliminary action before attempting to remove the nitride layer. This preliminary etching step prepares the surface by revealing the macrostructure and making the nitride layer identifiable, ensuring that subsequent removal operations are targeted and complete.
2Reliability
If entire blade is machined to remove coating and deterioration layer, then complete removal is achieved, but excessive material is removed and repair efficiency is reduced
Solution Approach 1:
The patent applies local quality by using electrolytic etching to selectively reveal and remove only the deteriorated portions of the base material where nitride layers are present. Instead of machining the entire blade, the process targets specific localized areas showing macrostructural changes, preserving healthy base material while removing only the affected regions.
Solution Approach 2:
Electrolytic etching serves as a localized intermediary process that identifies and removes deterioration only where needed. The etching solution selectively reacts with deteriorated material, allowing precise local removal rather than blanket machining of the entire blade component.
3Ease of manufacture
If thermal barrier coating is removed and base material is exposed, then deterioration layer can be accessed, but base material ductility is reduced due to nitride formation
Solution Approach 1:
Electrolytic etching acts as a gentle intermediary process that accesses and removes nitride layers without the mechanical stress of machining. This electrochemical process selectively removes brittle nitride layers while preserving the ductility of the underlying base material, avoiding further damage that would occur with mechanical removal methods.
Solution Approach 2:
The patent replaces mechanical machining with electrolytic etching for removing the nitride layer. This substitution of mechanical action with electrochemical action prevents further reduction in base material ductility, as the electrochemical process removes material without inducing mechanical stress or work hardening.
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
Reliably identifies and removes base material deterioration layers, preventing cracking and ensuring efficient repair by confirming complete removal through thickness measurements.
Implementation Method 1
a first etching step of etching the exposed base material; a first identification step of identifying a base material deterioration layer that is harder than the base material from the etched base material
Data Source
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AI summary
A gas turbine blade repair method including: a step in which a thermal barrier coating is removed to expose at least part of a base material of a gas turbine blade; a first etching step in which the exposed base material is etched; a first identification step in which a base material deterioration layer that is harder than the base material is identified from the etched base material; a first removal step in which the identified base material deterioration layer is removed; and a step in which, after a determination has been made in the first identification step that there is no base material deterioration