Corrosion Resistance of Atomic Layer Deposition-Generated Amorphous Thin Films

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Atomic layer deposition (ALD) enables precise control over thin film properties.
• Protecting aluminum from corrosive environments is crucial for many applications.
• Niobium and tantalum oxides are known for their chemical stability.

Purpose of the Study:

• To evaluate the etch resistance of amorphous Al2O3, Nb2O5, and Ta2O5 thin films prepared by ALD.
• To assess the suitability of these films as protective barrier layers for aluminum in caustic environments.
• To investigate the long-term stability and corrosion resistance of ALD coatings.

Main Methods:

• Amorphous thin films of Al2O3, Nb2O5, and Ta2O5 were deposited using ALD.
• Etch rates were measured in 10 M NH4OH using X-ray reflectometry.
• Surface morphology and roughness changes were analyzed using electron microscopy.
• Corrosion resistance of Nb2O5-coated aluminum was tested in 10 M NH4OH.

Main Results:

• Amorphous Al2O3 films exhibited an etch rate of 0.5 nm/min with increased roughness.
• Amorphous Nb2O5 and Ta2O5 films showed negligible etching or roughening after ~500 hours of immersion.
• An Nb2O5-coated aluminum block demonstrated no corrosion after 200 hours in 10 M NH4OH, indicating pinhole-free coatings.
• ALD-deposited Nb2O5 and Ta2O5 films displayed excellent stability in a highly alkaline solution.

Conclusions:

• Amorphous ALD Nb2O5 and Ta2O5 films are highly resistant to etching in 10 M NH4OH.
• These Nb2O5 and Ta2O5 coatings show potential as effective barrier layers for aluminum in caustic environments.
• ALD offers a viable method for producing robust protective coatings for metals in aggressive chemical conditions.