Laser Oxide Sealing of Machined Ceramic Turbine Surfaces
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Solution Overview
Problem
Ceramic materials used in gas turbine engines face challenges due to surface porosity, which can lead to infiltration of substances that accelerate undesirable reactions, reducing durability, and existing sealing methods can be costly and time-consuming.
Innovation Solution
A method involving machining a closed-pore surface to create an open-pore surface, followed by laser treatment to form an oxide that seals the pores, creating a closed-pore surface, potentially using ceramic matrix composites like silicon carbide or silicon nitride, with machining and laser treatment conducted concurrently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If machining is performed on ceramic surface to create features, then functional features are achieved, but surface porosity opens and durability decreases
Solution Approach 1:
The laser treatment is applied immediately after machining while the workpiece is still in position, sealing the opened pores before any harmful infiltration can occur. This preliminary sealing action prevents the durability issue from developing while maintaining the required feature geometry.
Solution Approach 2:
The laser-induced oxide layer acts as an intermediary substance that fills and seals the opened pores on the machined surface. This oxide intermediary restores the protective barrier function while allowing the underlying functional features to remain intact.
2Reliability
If traditional seal coating processes are used after machining, then surface sealing is achieved, but production time and cost increase
Solution Approach 1:
The sealing function is merged into the machining process itself by applying laser treatment in the same setup and sequence as machining. This combination eliminates the need for separate seal coating operations, reducing production time while achieving effective pore sealing.
Solution Approach 2:
The mechanical/chemical seal coating process is replaced with a laser-based thermal process. The laser induces oxide formation that seals pores through thermal-chemical mechanisms, eliminating the need for external coating materials and application equipment.
3Reliability
If extensive material removal is performed to seal pores, then pore sealing is achieved, but feature precision and material waste increase
Solution Approach 1:
The laser treatment parameters (power, speed, pulse duration) are optimized to induce oxide formation with minimal material removal. By controlling the thermal parameters, the process seals pores through oxide layer formation rather than through extensive material removal, preserving feature dimensional accuracy.
Solution Approach 2:
The laser induces phase transitions in the silicon-containing material, transforming it into oxide phases that seal the pores. This phase transition mechanism achieves sealing through chemical transformation rather than mechanical removal, minimizing impact on feature geometry.
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 effectively seals the surface, reducing porosity and minimizing material removal, potentially eliminating the need for post-machining seal coating processes, thereby enhancing durability and simplifying production.
Implementation Method 1
The open-pore machined surface is then laser-treated to cause formation of an oxide in the silicon-containing gas turbine engine article that seals the open-pore machined surface
Implementation Method 2
laser-treated to cause formation of an oxide in the silicon-containing gas turbine engine article that seals the open-pore machined surface
Data Source
AI summary
A method includes machining a closed-pore surface of a silicon-containing gas turbine engine article to produce a feature. The machining causes removal of the closed-pore surface to produce an open-pore machined surface. The open-pore machined surface is then laser-treated to cause formation of an oxide in the silicon-containing gas turbine engine article that seals the open-pore machined surface to produce a closed-pore treated surface.