Influence of ALD-Al₂O₃ film on anti-scratch and anti-tarnish of silver

Abstract

We report on atomic layer deposition (ALD) of Al 2 O 3 films onto 925 silver and assess their efficiency to prevent metal scratching and tarnishing. Films of five thicknesses (12, 16, 21, 25 and 31 nm) were deposited on the 925 silver. Optical characterization revealed that the colour difference of coated silver increased with film thickness, where the film thickness below 25 nm preserves the lustre of the silver. The tarnishing resistance increased with film thickness, and films thicker than 16 nm were resistant to corrosion in Na 2 S solution. The hardness and modulus of the film were 6.4 and 2 times that of 925 silver, respectively. Thicker films enhanced resistance to tarnishing and scratching and also led to a loss of lustre. A thickness of 25 nm was found to have an admirable combined performance. It is promising for applications of ALD process for silver protection.

Experimental investigation of the EDM tools coated with nano-alumina film

“…Kukli et al [24] proved that Al 2 O 3 coatings of nm thickness by ALD method can provide a certain insulating effect and enhance the surface hardness. Huang et al deposited Al 2 O 3 film on 925 silvers by ALD to enhance its anti-tarnish performance and anti-scratch performance [26].…”