In the high-stakes world of aero engine combustor liners, where temperatures soar and durability is paramount, a recent study is making waves. Researchers at the Center for Advanced Multidisciplinary Research and Innovation at Chennai Institute of Technology in India have been delving into the intricacies of thermal barrier coatings (TBCs), specifically the bond coats that play a crucial role in protecting engine components. The lead author, S Karthikeyan, and his team have published their findings in the journal Materials Research Express, which translates to “Expressions of Material Research” in English.
The study focuses on NiCrAlY bond coats applied over C-263 nickel-based super alloy, a material commonly used in aero engine combustor liners. The researchers investigated two deposition processes: atmospheric plasma spraying (APS) and high velocity oxy fuel (HVOF) spraying. Their goal was to understand how these processes affect the microstructure, thermal expansion behavior, and thermal conductivity of the bond coats.
“Thermal barrier coatings need extremely durable and suitable bond coats to survive in high temperature environments,” Karthikeyan explains. The bond coat’s performance is highly dependent on the deposition process, which controls its microstructure, porosity, thermal behavior, and resistance to thermal cycling. This is where the study’s findings become particularly interesting for the energy sector.
The results indicate that HVOF spray coatings exhibit a denser microstructure, reduced porosity, and improved thermal properties compared to those developed by the APS process. This is a significant discovery, as the durability and efficiency of aero engine components are directly tied to the quality of these coatings. “High velocity oxyfuel sprayed coatings show linearly increasing coefficient of thermal expansion (CTE) values and thermal conductivity, similar to the C263 substrate material,” Karthikeyan notes.
The study also confirmed the phase stability and compatibility of the NiCrAlY bond coats, with the NiAl3 phase absent in both APS and HVOF coatings. This is a critical finding, as phase stability is essential for the long-term performance of TBCs.
So, what does this mean for the energy sector? The improved thermal properties and durability of HVOF-sprayed NiCrAlY bond coats could lead to more efficient and long-lasting aero engine components. This, in turn, could reduce maintenance costs and improve the overall performance of aircraft engines. Moreover, the insights gained from this study could pave the way for developing advanced bond coats for other high-temperature applications in the energy sector.
As the world continues to push the boundaries of energy efficiency and durability, research like this is invaluable. It’s a testament to the power of scientific inquiry and its potential to drive innovation in the energy sector. With further research and development, the findings from this study could shape the future of thermal barrier coatings and their applications in high-temperature environments.