Page 91 - IJAMD-1-3

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

mitigation strategies and advanced protective measures efficacy of these advanced TBC systems, demonstrating
for enhancing the resilience and durability of turbine notable improvements in performance, as depicted in
components. Their work also emphasizes the importance Figure 4. Moreover, a predictive modeling technique for
of accounting for particle size, velocity, and flow estimating the lifespan of these turbine blade coatings was
characteristics, providing a comprehensive framework introduced, emphasizing the crucial aspect of mitigating
for optimizing material selection and coating techniques. erosion effects in high-temperature environments.
By integrating these factors into predictive models, Shin and Hamed performed comprehensive
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engineers can anticipate erosion patterns more accurately experiments to characterize the erosion resistance of
and implement targeted design modifications to improve plasma-sprayed 7 wt% YSZ TBCs applied on MCrAlY
the longevity of turbine blades under extreme operating bond coats and IN718 substrates, typically utilized in
conditions. GTE blade materials. Utilizing 26 µm particles, they
Branco et al. investigated the effects of SPE on zirconia conducted experimental runs at varying gas temperatures
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and alumina-based ceramic coatings under standard and velocities, considering different impingement
room temperature conditions. The experiment involved angles based on the Taguchi method. This approach was
subjecting the coatings to a stream of alumina particles, adopted to develop an effective experimental design
each averaging 50 µm in size, at a velocity of 70 m/s and aimed at identifying the key test parameters influencing
an impingement angle of 90°. His research, as presented TBC erosion rates. Moreover, through the application of
in Figure 2, revealed a significant correlation between Taguchi’s L9 orthogonal array and the analysis of variance,
the erosion rate and the porosity of the coatings. The the researchers investigated the impact of these parameters
researchers further deduced that the porosity influenced on the erosion rate of the TBCs. They observed that
the erosion rate in multiple ways. First, the presence of increased gas temperature, gas velocity, and impingement
porosity resulted in a reduction in the material’s resistance angles, as guided by the Taguchi design of experiments
to plastic deformation or chipping, especially at the void’s (DOE), led to elevated erosion rates. Notably, the study
extremity where mechanical support was lacking. Second, revealed that 77.07% of the erosion was attributed to
the concave surface within a void, not shielded by any particle impact velocity, 14.15% to gas temperature, and
surrounding void edge, was particularly susceptible to 3.56% to impingement angles. By analyzing the SEM
impacts from particles at angles exceeding the average surface images, the researchers detected the presence of
surface-to-impact angle. Finally, the existence of pores unmelted and partially melted ceramic powders in the
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weakened the overall strength of the material, acting as pre-tested samples, which were received from the devices.
stress concentrators and contributing to the increased However, these were notably absent in the post-tested
erosion rates observed. samples, indicating the transformation and alterations
Zhu et al. outlined the process behind the creation induced by the erosion process. 72,77
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of TBC for turbine blades, taking into account the impact Shin and Hamed conducted an experimental
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of erosion during operations at elevated temperatures investigation to analyze the impact of robust port
within rotorcraft propulsion systems, as shown in Figure 3. microstructures on the erosion resistance of air plasma-
Through comprehensive experiments simulating engine sprayed 7 wt % YSZ TBCs at elevated temperatures.
erosion and thermal gradient conditions, they verified the Two sets of YSZ TBCs with distinct microstructures,
A B

Figure 2. Erosion rate and fracture strength were analyzed in relation to porosity in various alumina and titania-zirconia based materials, both in their
initial form and after heat treatment. (A) Porosity versus erosion rate. (B) Porosity versus modulus of rupture. Source: Branco et al. 58

Volume 1 Issue 3 (2024) 85 doi: 10.36922/ijamd.5188