Coating of Al-Cu Alloy with Ti-N Graded Film by Reactive DC Sputtering

抄録

Coating of Al-Cu alloy with Ti-N graded film was examined by reactive DC sputtering, in order not only to improve the surface hardness and the corrosion resistance or the biocompatibility of the aluminum alloy but also to relax the stress concentrated at the interface between the coated film and the alloy substrate. The deposition of the Ti-N graded coatings were realized by varying continuously nitrogen content in Ar-N₂ sputter gas during the reactive sputtering. Deposited films appeared to be uniform and adhesive, and their color tone was bronze with a red tinge. Their surface hardness reached over Hv1400. According to GDOES (Glow Discharge Optical Emission Spectroscopy) in-depth profiles, the nitrogen concentration in the film gradually decreased in depth direction from the surface toward the alloy substrate, confirming that Ti-N graded film had formed on the alloy substrate. On the basis of XRD, it was assumed that not only a-titanium phase but also titanium nitride phases such as TiN and Ti₂N were formed in the graded film. Furthermore it was confirmed that the corrosion protective property of the AlCu alloy could be improved by coating it with the graded coating.