Ceramic Multilayer Erosion Coating for Gas Turbines
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Solution Overview
Problem
Conventional erosion protection coatings with alternating metal and ceramic layers experience a reduction in erosion protection effect at operating temperatures between 500° C. and 700° C., especially at 600° C., due to inter-diffusion and brittle phase formation, and are less effective with small incident angles of erosion particles.
Innovation Solution
A purely ceramic multilayer erosion protection coating is developed, comprising alternating relatively hard CrAlN layers and relatively soft CrN layers, with specific layer thicknesses and nanostructured designs, applied using PVD methods, and optionally including a ductile graded CrN bonding layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal and ceramic layered erosion protection coatings are used, then the coating provides initial erosion protection, but at operating temperatures between 500°C and 700°C the erosion protection effect is reduced due to inter-diffusion and brittle phase formation
Solution Approach 1:
The patent changes the material composition parameter by replacing metal layers with ceramic layers throughout the coating structure. This fundamental parameter change eliminates the inter-diffusion and brittle phase formation issues that occur at high temperatures in conventional metal-ceramic coatings, while maintaining the multilayer structure's erosion protection capabilities.
Solution Approach 2:
The patent employs a composite ceramic-ceramic multilayer structure where hard ceramic layers (such as CrAlN, TiAlN, or Al2O3) alternate with soft ceramic layers (such as CrN or TiN). This composite approach combines the high-temperature stability of ceramics with the protective benefits of multilayer construction, achieving both erosion resistance and compositional stability at elevated temperatures.
2Ease of manufacture
If conventional metal layers are used in the erosion protection coating, then the coating can be manufactured with standard processes, but the metal layers cause negative modification of physical and mechanical properties at high temperatures
Solution Approach 1:
The patent changes the material parameter from metal to ceramic for all layers in the coating. This substitution maintains compatibility with PVD manufacturing processes while eliminating the high-temperature degradation issues associated with metal layers, thereby preserving ease of manufacture while dramatically improving high-temperature mechanical properties.
3Reliability
If a purely ceramic multilayer coating is used, then erosion protection is maintained at high temperatures and small incident angles, but the coating requires precise control of layer thickness and material composition
Solution Approach 1:
The patent specifies precise parameter ranges for layer thickness (hard layers: 0.5-10 μm, soft layers: 0.5-5 μm) and material composition (Al content: 5-40 at.%, Cr content: 50-60 at.%). These controlled parameters enable the purely ceramic multilayer structure to achieve optimal erosion protection at high temperatures while remaining manufacturable through PVD processes with standard precision capabilities.
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 ceramic multilayer coating maintains effective erosion protection at high temperatures and small incident angles, enhancing durability and performance compared to conventional metal-based coatings.
Implementation Method 1
The relatively hard layers (12) and the relatively soft layers (13) are thus disposed in an alternating manner on top of one another in such a way that an outer-lying layer, which forms an outer surface of erosion protection coating (11), is formed as a relatively hard layer (12)
Data Source
AI summary
The invention relates to an erosion protection coating (11), in particular, for gas turbine components, having a horizontally segmented and/or multi-layered construction. i.e., having at least one relatively hard layer (12) and having at least one relatively soft layer (13), wherein the relatively hard layer or each relatively hard layer as well as the relatively soft layer or each relatively soft layer are disposed on top of one another in an alternating manner, in such a way that an outer-lying layer, which forms an outer surface of the erosion protection coating, is formed as a relatively hard layer (12). According to the invention, the relatively hard layer or each relatively hard layer (12) as well as the relatively soft layer or each relatively soft layer (13) are formed as a ceramic layer in each case.