Pitting corrosion – Preferred chloride diffusion pathways in physical vapor deposited AlCrN coatings
Pitting corrosion of sputtered and arc evaportaed fcc-AlCrN coated low-alloy steel substrates was studied in a 0.1 M NaCl solution, using a three-electrode-cell. Depending on the deposition technique, several diffusion mechanisms were identified by high-resolution techniques (i.e. APT, TOF-SIMS). For arc evaporated AlCrN, incoherently embedded macro-particles provided the majority of fast-track diffusion pathways and pit-initiation sites, while their pristine coating matrix proved protective against chloride inward diffusion. Contrarily, the more coarse-grained sputtered AlCrN morphology with a highly orientated crystal growth featured diffusion paths along column boundaries, where chloride permeated the coating structure and initiated pit formations at the coating-substrate interface. Data Availability Statement The data that support the findings of this study are available from the corresponding author upon reasonable request.
O.E. Hudak, A. Bahr, P. Kutrowatz, T. Wojcik, F. Bohrn, L. Solyom, R. Schuster, L. Shang, O. Hunold, P. Polcik, M. Heller, P. Felfer, G. Ball, H. Riedl