Page 74 - IJAMD-1-3

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

exacerbates creep deformation and fatigue. 11,20 Factors from particle impacts. 12,23,24 In addition, porous coatings,
affecting erosion rates are tabulated and described in such as those tested by other authors, are more susceptible
Table 2. to erosion because the voids within the coating material
weaken its structural resistance, allowing particles to chip
1.2. Influencing factors on erosion damage or erode sections of the surface more easily. Advanced
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Particle velocity, size, and density are significant coatings such as thermal barrier coatings (TBCs) are
determinants of erosion severity. Higher particle often applied to mitigate this erosion; however, once these
velocities lead to more forceful impacts, resulting in coatings wear away, the underlying material becomes
more extensive material degradation. 8,9,21,22 Fang et al., exposed to the full force of particle impacts. 6,9,10,26 Turbine
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conducted experiments that demonstrated how particles blades are constantly exposed to extreme temperatures,
with velocities between 100 and 500 m/s and diameters which play a critical role in the rate and extent of erosion-
ranging from 1 to 5 mm caused considerable erosion, induced damage. High temperatures promote oxidation
highlighting the critical role of particle characteristics in and thermal fatigue, which further erode the blade surface
erosion dynamics. The angle at which particles collide with over time. 10,11 The thermal stresses involved weaken the
the blade surface also influences erosion outcomes. High blade material and accelerate erosion, especially when
impact angles (close to 90°) allow for maximum kinetic combined with the impact of high-speed particles.
energy transfer, leading to greater material removal. Lower Past researches showed that erosion rates increase with
angles, by contrast, cause surface deformation rather than temperature and gas velocity, and higher operating
significant material loss, resulting in a smoother erosion temperatures contribute to material softening, which
pattern but not less overall wear over time. 10,11 Researchers exacerbates the effects of erosion. 12,27,28 This is particularly
observed that high-angle impacts cause more severe critical in high-temperature regions of the turbine where
erosion on the blade leading edge, where impacts are direct protective coatings may degrade over time, exposing the
and forceful. base material to accelerated wear. Moreover, the synergistic

The blade material’s hardness, toughness, and coating effect of thermal fatigue and particle impingement can
type are central to its resistance against erosion. Harder significantly reduce the operational lifespan of turbine
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materials generally exhibit higher erosion resistance, as blades. Table 3 presents the influence of particle
they are able to better absorb and dissipate the energy characteristics on erosion.
Table 1. Failure mechanisms in gas turbine blades

Failure mechanism Description Contributing factors Impact on blade performance
Solid particle erosion Material loss caused by high-velocity Particle velocity, size, angle of impact, Surface damage, reduced
particle impacts and material properties aerodynamic efficiency
Fatigue Propagation of stress-induced cracks Stress concentrators, thermal cycling, Structural weakness and eventual
due to repeated loading cycles and material properties blade failure
Oxidation and Decline of material properties due to High temperatures, exposure to Accelerated material loss and
corrosion chemical reactions oxidizing gases, and erosion reduced durability
Creep Time-dependent deformation under Elevated temperatures, Reduced load-bearing capacity and
constant stress in high-temperature erosion-induced thinning of material rupture
conditions

Table 2. Factors affecting erosion rates

Factor Description Effect on erosion Mitigation strategies
Particle properties Velocity, size, density, and hardness of Increases material loss with higher values Use harder materials and optimized
particles of each parameter coatings
Operational Gas and material temperatures during Accelerates oxidation, thermal fatigue, Apply heat-resistant coatings
temperature turbine operation and material softening (e.g., TBCs)
Blade geometry Shape and surface profile of blades Irregular geometries increase turbulence Optimize blade design to minimize
and particle impingement flow separation
Environmental Presence of oxidizing and corrosive Accelerates chemical degradation and Use anti-corrosion coatings and
conditions gases erosion synergistically maintain controlled environments
Abbreviation: TBCs: Thermal barrier coatings.

Volume 1 Issue 3 (2024) 68 doi: 10.36922/ijamd.5188