Korozija in zaščita nepatiniranega, sulfidno- inkloridno-patiniranega brona

The surface of bronze undergoes changes when it is exposed to a polluted atmosphere, and bronze should therefore be protected from this natural deterioration. The most common protective coating currently in use is Incralac, which includes toxic components and is reported to dissolve a few months after application. This work therefore investigates a fluoropolymer-based coating (FA-MS), and compares it to the protection offered by Incralac. Bronze samples (non-patinated, sulphide-patinated or chloride-patinated) were exposed to simulated urban rain for four months. The corrosion products formed were characterised using SEM/EDS and Raman analyses. To study the protection efficiency of the newly developed fluoropolymer coating (FA-MS) and Incralac protection, various electrochemical methods were used: measurements of open circuit potential linear polarisation and potentiodynamic measurements. Findings show that the FA-MS coating provides a protection efficiency of 71 % for chloride-patinated bronze and 99.5 % for sulphide-patinated bronze. Contact angles of the FA-MS samples were higher than those of the unprotected samples or the samples protected by Incralac, indicating better hydrophobic properties of the FA-MS coating. Povšina brona se z izpostavljenostjo onesnaženemu okolju spreminja, zato mora biti pred naravnim propadanjem zaščitena. Trenutno je najbolj pogosto uporabljen zaščitni premaz Incralac, ki vsebuje okolju škodljive snovi, hkrati pa poročajo, da po nanosu razpade že po nekaj mesecih. Na podlagi tega je bil v tej študiji raziskan zaščitni premaz na osnovi fluoropolimera (FA-MS), ter primerjava z Incralac premazom. Vzorci brona (ne-patiniran, rjavo-patiniran in kloridno-patiniran) so bili za štiri mesece izpostavljeni simulaciji deževnice v urbanem okolju. Tvorjeni korozijski produkti so bili nato označeni s pomočjo SEM/EDS in ramanske analize. Za študij učinkovitosti zaščite novo razvitega fluoropolimernega premaza (FA-MS) in Incralac zaščite smo uporabili različne elektrokemijske metode: meritve potenciala odprtega kroga, linearno polarizacijo in potenciodinamske meritve. Prav tako smo določili hidrofobnost z meritvami kontaktnih kotov in izmerili spremembe v barvi pred in po nanosu zaščite. Ugotovitve preiskav so, da FA-MS premaz nudi učinkovitost zaščite v vrednosti 71 % za kloridno patiniran bron in 99,5 % za sulfidno patiniran bron. Izmerjene vrednosti kontaktnih kotov vzorcev, zaščitenih s FA-MS prevleko, so bili višje kot pri nezaščitenih vzorcih in vzorcih, zaščitenih z Incralacom, kar kaže na izboljšane hidrofobne lastnosti FA-MS zaščite.