An adhesion analysis of thin carbon films deposited onto curved and flat Ti6Al4V substrates using rf magnetron sputtering and plasma enhanced chemical vapor deposition techniques

By depositing thin-films of carbon onto both curved and flat Ti6Al4V substrates, and then performing a Scotch tape adhesion test on the resultant films, we assess the role that the geometry associated with the underlying substrate plays in shaping the quality of the adhesion of the thin-films of carbon. Both rf magnetron sputtering and plasma enhanced chemical vapor deposition techniques are employed for the purposes of this study. For the specific case of rf magnetron sputtering, we find that thin-films of carbon deposited onto curved Ti6Al4V substrates adhere better to the underlying substrate than those deposited onto flat Ti6Al4V substrates. In contrast, for the case of plasma enhanced chemical vapor deposition, the thin-films of carbon deposited onto curved Ti6Al4V substrates exhibit the same adhesion quality as those deposited onto flat Ti6Al4V substrates. Through the use of Raman spectroscopy, for the specific case of rf magnetron sputtering, it is shown that there is very little difference in the underlying chemistry of the deposited thin-films of carbon. This suggests that it is the geometry of the substrate itself that is playing a role in determining the nature of the adhesion for the case of rf magnetron sputtering. We suspect that the physical vapor deposition nature of rf magnetron sputtering may be responsible for this observed difference, plasma enhanced chemical vapor depositions being more shaped by the chemical reactions at the growth surface.