Page 95 - IJAMD-1-3

International Journal of AI for
Materials and Design
Review of gas turbine blade failures by erosion

4.1.4. Thermal and mechanical fatigue resistance protection but also resists the mechanical wear caused by

Thermal cycling and mechanical loading contribute to material high-velocity particles. Engineers should also consider
fatigue, especially in areas with high particle impingement and coating thickness: thicker coatings provide greater
elevated temperatures. Oxidation and creep damage further protection, but excessive thickness can introduce stresses
that may cause premature failure. Optimal thickness must
exacerbate erosion by degrading the material’s strength and
resistance to wear. Experimental data suggest that coatings be balanced based on operational conditions.
and materials that provide both thermal barrier properties By directly linking experimental findings to practical
and high resistance to oxidation can significantly reduce mitigation strategies, engineers can make informed
erosion-induced damage. The application of TBCs, such as decisions on materials, coatings, and design modifications
YSZ, offers excellent protection against high-temperature to improve turbine blade durability. Through the careful
oxidation and thermal fatigue. These coatings not only insulate selection of coating techniques, material properties, and
the underlying material from extreme heat but also improve geometrical adjustments, engineers can reduce erosion,
overall blade longevity. MCrAlY bond coatings, typically used enhance material resilience, and extend the operational
in combination with TBCs, enhance adhesion and resistance lifespan of gas turbines under harsh conditions. These
to oxidation. For applications subject to extreme temperature strategies help bridge the gap between theoretical erosion
variations, selecting CMCs can provide superior resistance to studies and real-world turbine performance optimization.
both erosion and high-temperature fatigue. Table 13 offers a comprehensive overview of erosion effects
under varying conditions and materials.
4.1.5. Multi-layer coating systems
5. Results and discussion
Multi-layer coatings, where a bond coat is applied before
the top ceramic or metallic coating, have proven effective Erosion-induced gas turbine blade failures have been
in enhancing erosion resistance. The bond coat serves as extensively studied and have been found to significantly
a buffer to accommodate thermal expansion differences impact the efficiency and lifespan of gas turbines. The
between the base material and the top coating, preventing potential causes and mechanisms of erosion can involve
spallation under thermal cycling or particle impacts. various factors, including the impingement of solid
A multi-layer approach using materials such as MCrAlY particles, high-velocity fluid flows, and abrasive wear.
(bond coat) followed by ceramic or metallic topcoats Researchers have often emphasized the crucial role of
(e.g., TBCs or tungsten carbide) significantly improves material selection, surface coatings, and cooling techniques
blade durability. This system not only enhances thermal in mitigating erosion effects and enhancing the durability

Table 13. Comparative summary of erosion effects under different conditions

Figure* Material/Coating Experimental parameter Erosion effects observed Key insights
Figure 2 Nickel-based Elevated temperatures (600 Increased oxidation and thermal fatigue Temperature amplifies erosion
superalloy – 1000°C) exacerbate erosion effects at higher through combined thermal and
temperatures. mechanical stresses.
Figure 3 Micro-grooved High particle velocity with Reduced material loss compared to flat Surface texturing effectively reduces
surface coating turbulent flow regime coatings; grooves divert particles away erosion by modifying particle
from high-stress regions. trajectories.
Figure 4 Serrated trailing Impact of modified blade Erosion effects significantly reduced; Geometrical modifications reduce
edge design geometry smoother airflow with less turbulence turbulence and improve erosion
and particle impingement. resistance.
Figure 5 Hybrid thermal Layered protection under Excellent thermal resistance; erosion Multi-layer designs enhance both
barrier coating extreme temperature localized to the top layer, preserving the thermal and erosion resistance.
gradients substrate.
Figure 6 Finely textured Micro-texturing effects on Improved particle deflection; significantly Micro-textures effectively reduce
blade surface particle deflection reduced material loss compared to erosion by altering particle
untextured surfaces. trajectories.
Figure 7 Blunt trailing edge High-velocity turbulent flow Increased material wear at the trailing Wake turbulence can be mitigated
design impacts edge due to wake turbulence; redesign with smoother trailing-edge designs.
reduces peak erosion rates.
Note: *This summary is in reference to the figures presented in this article.
Abbreviations: CMC: Ceramic matrix composite; YSZ: Yttria-stabilized zirconia.

Volume 1 Issue 3 (2024) 89 doi: 10.36922/ijamd.5188