Materials E-Guide
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OEMs in the aerospace market seek for solutions to maintain the maximum sealing efficiency across all turbine stages — for the widest range of operating conditions and longest service periods possible. At the same time, it is vital to prevent rub damage to rotating blades and stator shrouds, and prevent engine surges.
Increased Efficiency, Fewer Emissions
Oerlikon Metco’s specialized material and abradable coating solutions seal the gas path and improve performance and efficiency of aero engines. They are a key component in engine operation safety and the optimal answer for a variety of use cases, as they can be customized to suit the turbine design and operating conditions. Furthermore, they can also be applied and repaired cost effectively.
Our abradable coatings allow engines to operate using less fuel (1% to 3% efficiency gain) and as a result have a positive environmental benefit of reduced CO2 generation and NOx emissions.
Compared to other technologies such as felt metals, brush seals and mechanical clearance control systems, they have a true competitive advantage for our customers. As a further advantage, thermal spray abradables can also be applied and repaired at lower overall cost.
Compressor Sealing
Low pressure compressor (LPC) systems drive and compress high volumes of air from the external environment into the high pressure compressor section. The higher the sealing efficiency, the lower the fuel consumption, CO2 generation and NOx emissions. Oerlikon Metco’s abradable coatings are a key element in engine operation safety and allow efficiency gains up to 3%.
Oerlikon Metco’s unique aluminum alloy-polyester abradable clearance control coating systems are applied using thermal spray technology and represent the hallmark for thermal sprayed compressor abradables. They have been used in aero engines low pressure seals for more than half a century by major OEMs air carriers for their aero engine fleets — literally hundreds of millions of hours of service have been accumulated globally over time.
Never satisfied with the status quo, Oerlikon Metco continues to develop abradable technologies for LPC applications. For example, a new LPC abradable material that is more corrosion resistant than previous offerings while maintaining clearance control efficiency, is making inroads on flight gas turbine engines.
High Pressure Turbine (HPT) Seals
Porous ceramic based abradable clearance control coating systems are applied using plasma spray technology. The coatings show excellent abradability characteristics with minimal blade wear and allow for significant cost-savings and environmental benefits.
The material and coating design depend on service temperatures and component types. The parameters can be adjusted to control porosity levels, hardness and erosion resistance, thereby accommodating the operating characteristics of specific engines.
A 25 μm reduction in tip clearance in a high pressure turbine (HPT) can lead to a 0.1% reduction in Specific Fuel Consumption rate (SFC) which translates to some 0.02 billion gallons of fuel saving annually for US airlines. (Lattime & Steinetz, ”Journal of Propulsion and Power”, vol. 20, no. 2, 2004, p.302–311.)