| Abstract | Brojne metalne konstrukcije izložene su morskoj vodi. Kao najzastupljeniji konstrukcijski materijal , zbog dobrih fizikalnih i kemijskih svojstava, koristi se čelik. Morska voda, kao jako agresivan medij, uzrokuje brojna oštećenja na brodovima koji plove, a korozijsko djelovanje značajno je i u slučaju potonulih brodova. U teorijskom dijelu ovog rada objašnjene su vrste korozije koje se javljaju kod potonulih brodova. Naglasak je na rupičastoj koroziji i koroziji u procjepu koje su najznačajnije vrste korozije potonulih brodova. Bitno je spomenuti da se korozijski procesi u plitkoj vodi razlikuju od onih u dubokomorskom okruženju. Na dnu mora vlada velika tama stoga je i temperatura vrlo niska, a s dubinom mora opada i koncentracija kisika, reaktanta ključnog za odvijanje korozije. Pregledni dio rada sadrži primjere potonulih brodova te njihovu zaštitu. 2001. godine UNESCO donosi Konvenciju zaštite podvodne kulturne baštine kojoj pripadaju i potonuli brodovi. Njihova zaštita od korozije važna je stavka spomenute Konvencije te se raznim postupcima to cilja i ostvariti. Primjer je James Matthews, brod izrađen početkom 19. stoljeća, istražen je odmah nakon pronalaska na zapadnoj obali Australije u smislu njegova korozijskog stanja i površinskog pH. In-situ zaštita od korozije se primijenila s cinkovim žrtvovanim anodama koje su se pokazale izrazito djelotvornima. Kod potonulih japanskih brodova u Chuuk Lagoon-i, u južnom dijelu Tihog oceana, uz problem korozije te primjenu zaštite također s cinkovim žrtvovanim anodama, javio se problem razaranja spremnika ulja i goriva zbog korozije i curenja ulja koje predstavlja problem okolnim otocima. Obrnuta situacija javlja se u Meksičkom zaljevu gdje ulje izliveno tijekom nesreće s bušotinom Deepwater Horizon utječe na stanje i koroziju tamošnjih potonulih brodova. Potonuli brodovi na iznimno velikim dubinama (>2000m) pokazuju specifične produkte korozije u obliku tzv. rustikula. |
| Abstract (english) | Numerous metal structures are exposed to sea water. The most common used construction material is steel due to its good physical and chemical properties. Seawater, as a very aggressive medium, causes numerous damages to ships that sail and significant corrosion to ships that sink. This paper explains the types of corrosion that occur in sunken ships. The emphasis is on pitting corrosion and crevice corrosion, which are the most significant types of corrosion of sunken ships. It is important to mention that corrosion processes in shallow waters are different from those in the deep sea environment. At the bottom of the sea, the temperatures are very low, and with the depth of the sea, the concentration of oxygen, which is crucial for the corrosion process, also decreases. The overview part of this paper states examples of sunken ships and their protection. In 2001, UNESCO passed the Convention for the Protection of Underwater Cultural Heritage, which also includes sunken ships. Their protection from corrosion is an important item of the aforementioned Convention, and it is aimed to be achieved through various procedures. For example James Matthews, a ship built in the early 19th century, was investigated immediately after its discovery on the west coast of Australia in terms of its corrosive state and surface pH. In-situ corrosion protection was applied with a zinc galvanic anodes, which proved to be extremely effective. With sunken Japanese ships in Chuuk Lagoon, in the southern part of the Pacific Ocean, in addition to the problem of corrosiveness and the application of protection with zinc galvanic anode, there was also the problem of destruction of oil and fuel tanks due to corrosion and oil leaks which created a problem for the surrounding islands. The reverse situation occurs in the Gulf of Mexico, where the oil, spilled during the Deepwater Horizon drilling accident, is affecting the condition and corrosion of sunken ships in the specified area. Sunken ships at extremely deep depths (>2000m) show specific corrosion products in the form of so-called rusticile. |
