A modified blister test to study the adhesion of thin coatings based on local helium ion implantation

In this work, we present the first results of this blister test applied to W-C:H films and multilayers of Ti and Al deposited by Physical Vapour Deposition on polycrystalline copper substrates. The copper substrates were implanted with 34 keV He+ ions up to fluences of 3 and 5×1016 cm−2 before the deposition of the coatings and annealed afterwards in vacuum at temperatures from 773 to 1073 K for 30 min. Delamination of the Ti/Al multilayer coatings was already detected after annealing at 873 K with an energy release rate estimated to be 0.5 J m−2 at a typical helium pressure of 107 Pa. No delamination but only helium swelling was observed for W-C:H coatings annealed at 1073 K. Results of experiments on uncoated copper samples are also shown in order to explain the mechanism of helium bubble growth and helium release that causes the creation of the blisters.