Corrosion properties of Cu - Ni alloys in seawater

Legure bakra s niklom predstavljaju važnu skupinu konstrukcijskih materijala visokih svojstava korozijske postojanosti. Stoga se primjenjuju za izradu različitih konstrukcija izloženih agresivnom okolišu, a to se prije svega odnosi na okoliš u kojem je prisutna morska voda. Iako ih odlikuje visoka otpornost na morsku vodu, koja se temelji na spontanom nastanku zaštitnog oksidnog filma bakrenih oksida, u određenim uvjetima može doći do pojave lokalnih oblika razaranja poput rupičaste korozije ili korozije u procjepu. U teorijskom dijelu opisane su podjela i svojstva legura bakra s niklom te je detaljno izučena njihova korozijska postojanost i mogući oblici oštećivanja u morskom okolišu. U eksperimentalnom dijelu rada provedeno je laboratorijsko elektrokemijsko korozijsko ispitivanje Cu – Ni legura uronjenih u prirodnoj i onečišćenoj morskoj vodi prije ispitivanja. Uzorci su bili uronjeni 7 i 14 dana u morsku vodu, a određen broj uzoraka nije bio uronjen prije ispitivanja. Temperatura morske vode pri ispitivanju iznosila je 20 i 60 °C. Rezultati ispitivanja su analizirani te su izvedeni zaključci.Copper – nickel alloys represent an important group of metal materials with high corrosion resistance properties. It is therefore used for the construction of various structures exposed to aggressive environment, which is primarily related to the environment in which the sea water is present. Although characterized by high seawater resistance, which is based on the spontaneous formation of a protective oxide film of copper oxide, under certain conditions, local forms of damage such as pitting corrosion or crevice corrosion may occur. The theoretical part describes the division and properties of copper - nickel alloys and their corrosion resistance and possible forms of damage in the marine environment have been studied in detail. In the experimental part, a laboratory electrochemical corrosion test of Cu - Ni alloys was carried out, samples were immersed in natural and contaminated seawater prior to testing. The samples were immersed for 7 and 14 days in seawater, but a number of samples were not immersed before the test. Temperature of the seawater during the test was 20 and 60 ° C. The test results were analyzed and conclusions were drawn