Nanojoining with Ni Nanoparticles for Turbine Applications

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• High-temperature joining processes like brazing can degrade monocrystalline superalloys used in turbines due to thermal stresses and recrystallization.
• Current brazing temperatures (around 1200°C) can negatively impact material properties, necessitating lower-temperature alternatives.
• Nanojoining, utilizing the 'surface effect' of nanoparticles, offers a promising route to reduce joining temperatures and preserve material integrity.

Purpose of the Study:

• To investigate the potential of nanojoining using nickel nanoparticles for high-temperature applications, specifically for the nickel-based superalloy PWA 1483.
• To reduce joining temperatures compared to conventional brazing without compromising material properties.
• To explore the influence of process parameters on the microstructure and mechanical properties of nanojoined PWA 1483.

Main Methods:

• Utilized nickel nanoparticles for joining the nickel-based superalloy PWA 1483 via induction heating.
• Varied key joining parameters: brazing temperature, holding time, and surface treatment of base materials.
• Analyzed the resulting joint microstructure and measured tensile shear strength.

Main Results:

• Successful nanojoining of PWA 1483 was achieved using nickel nanoparticles, demonstrating the feasibility of this approach.
• The microstructure of the joint was found to be dependent on temperature and holding time, with insufficient sintering observed at suboptimal conditions.
• Achieved tensile shear strength of up to 165 MPa under optimized joining conditions, indicating promising mechanical performance.

Conclusions:

• Nanojoining with nickel nanoparticles presents a viable alternative to high-temperature brazing for nickel-based superalloys in demanding applications like gas turbines.
• Optimized process parameters are crucial for achieving adequate sintering and desirable mechanical properties.
• This technique offers a pathway to preserve critical material properties by significantly lowering joining temperatures.