Aircraft Engine Flow Element Coating for Hot Gas Corrosion
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Solution Overview
Problem
Combustion chamber tile elements in aircraft engines face reduced service life due to hot gas corrosion and thermal insulation layer failure, with existing solutions like single-crystal materials being costly and inefficient.
Innovation Solution
A flow element with a chromium-plating layer on all surfaces, an adhesive MCrAlY layer in high-stress areas, an aluminate layer, and a thermal barrier coating, forming a chromium-aluminate layer in low-stress areas, to enhance corrosion resistance and thermal protection while minimizing aluminum content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-crystal base materials are used to protect against hot gas corrosion and thermal loads, then corrosion resistance and service life are improved, but production costs and manufacturing complexity increase significantly
Solution Approach 1:
The patent applies different coating compositions to different surfaces of the flow element. The hot-gas surface receives a coating with lower Al content (10-30 wt%) to resist thermo-mechanical fatigue, while the surface facing away from the gas flow receives a coating with higher Al content (30-60 wt%) for oxidation protection. This localized differentiation allows each surface to have optimized protection without requiring expensive single-crystal materials throughout.
Solution Approach 2:
The patent uses composite coating structures combining multiple materials: a chromium-plating layer as base, an adhesive MCrAlY layer, an aluminate layer, and a thermal barrier coating. This multi-layer composite approach provides comprehensive protection against both corrosion and thermal loads while using cost-effective materials compared to single-crystal alternatives.
2Reliability
If high aluminum content is used in the coating to provide oxidation protection, then oxidative resistance is improved, but resistance to thermo-mechanical fatigue-induced cracking decreases
Solution Approach 1:
The patent differentiates aluminum content by surface location. The hot-gas surface has lower Al content (10-30 wt%) to maintain strength and resist thermo-mechanical fatigue, while the opposite surface has higher Al content (30-60 wt%) for oxidation protection. This spatial differentiation resolves the contradiction by providing appropriate Al content where needed without compromising overall performance.
Solution Approach 2:
The coating is segmented into distinct functional layers: a chromium-plating layer, an adhesive MCrAlY layer, an aluminate layer with controlled Al content, and a thermal barrier coating. This segmentation allows each layer to perform its specific function optimally, with the aluminate layer providing oxidation protection while the overall structure maintains fatigue resistance.
3Temperature
If a complete thermal insulation layer is applied to protect the base material from high temperatures, then thermal protection is improved, but the coating costs and manufacturing complexity increase
Solution Approach 1:
The patent applies thermal barrier coating only in first partial areas where the adhesive layer is present, rather than uniformly across the entire surface. This localized application provides thermal protection where most needed while reducing overall coating complexity and cost compared to complete coverage.
Solution Approach 2:
The coating system is segmented into functional zones: areas with complete protection (adhesive layer + aluminate layer + thermal barrier coating) and areas with simplified protection (chromium-plating layer only). This segmentation optimizes the balance between thermal protection and manufacturing complexity by applying full protection only where necessary.
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 solution increases resistance to thermo-mechanical fatigue and corrosion, extending the service life of the flow element and reducing maintenance costs by providing effective thermal and oxidative protection across a wide temperature range.
Implementation Method 1
the base material is completely surrounded by a chromium-plating layer on the hot-gas surface and on the surface facing away
Implementation Method 2
the flow element having an adhesive layer on the chromium-plating layer in first partial areas
Implementation Method 3
the flow element having an aluminate layer, the aluminate coat in the first partial areas is arranged on the adhesive layer
Implementation Method 4
a thermal barrier coating being arranged on the alitizing layer in the first partial areas
Implementation Method 5
the chroming layer and the alitizing layer forming a chroming-alitizing layer in the second partial areas
Data Source
Figure 1
AI summary
The invention relates to a flow element (1) for fluidic contact with a hot gas flow (15) within an aircraft engine, wherein the flow element (1) comprises a base material (2), which has a hot gas surface (12) facing the gas flow (15) and a turned-away surface (16) facing away from the gas flow (15), wherein the base material (2) is completely surrounded by a chroming layer (3) on the hot gas surface (12) and on the turned-away surface (16), wherein the flow element (1) has an adhesion layer (13) on the chroming layer (3) in first partial regions, wherein the flow element (1) has an alitizing layer (5), wherein the alitizing layer (5) is arranged on the adhesion layer (13) in the first partial regions, wherein a thermal insulation layer (14) is arranged on the alitizing layer (5) in the first partial regions, and the alitizing layer (5) is arranged on the chroming layer (3) in the second partial regions, which do not have the adhesion layer (13), wherein the chroming layer (3) and the alitizing layer (5) form a chroming-alitizing layer (4) in said second partial regions.