Corrosion resistance of aluminium alloy AA5083

Završni rad sastoji se od dvije cjeline: teorijskog i eksperimentalnog dijela. U teorijskom dijelu dana su svojstva aluminija te je napravljena podjela aluminijskih legura s posebnim osvrtom na one koje se primjenjuju u brodogradnji. Jedan od najvažnijih razloga primjene aluminija kao konstrukcijskog materijala je dobra korozijska postojanost te je stoga dano poglavlje o koroziji; vrstama korozije, metodama zaštite te ekonomskom značaju korozije u brodogradnji. Izučena su svojstva korozijske postojanosti aluminijskih legura grupe 5000, a na kraju teorijskog dijela rada prikazana je primjena aluminijskih legura u maloj brodogradnji na primjeru brodogradilišta „Colnago Marine“. U eksperimentalnom dijelu provedena su elektrokemijska ispitivanja aluminijske legure AA – 5083 u 3,5 % otopini natrijevog klorida s ciljem utvrđivanja korozijskih parametara materijala. Ispitivanja su provedena pri sobnoj i povišenoj temperaturi. Površina uzorka uspoređena je vizualno prije i poslije izlaganja 3,5 % otopini NaCl – a, a rezultati eksperimenta izneseni su u obliku dijagrama (potenciostatske krivulje) iz kojih su iščitane korozijske veličine – korozijski potencijal, polarizacijski otpor i brzina korozije. Na kraju je dana usporedba rezultata nakon provedbe eksperimenta pri sobnoj i povišenoj temperaturi te je iznesen zaključak.This final paper consists of two main units: theoretical and experimental part. In the theoretical part of this paper, properties of aluminium are provided and division of aluminium alloys is made, with special reference to those used in shipbuilding. One of the most important reasons for the use of aluminium as a constructing material is its good corrosion resistance. Therefore, within this paper, a chapter on corrosion is provided; further, types of corrosion, methods of protection and the economic importance of corrosion in shipbuilding are described. Furthermore, properties of corrosion resistance of aluminium alloys of Group 5000 have been carefully studied, while at the end of the theoretical part of this paper, application of aluminium alloys in small shipbuilding is demonstrated, with special emphasis on the example of shipyard "Colnago Marine". In the experimental part of this paper, electrochemical tests of aluminium alloy AA - 5083 were performed in 3.5% sodium chloride solution, in order to determine the corrosion parameters of the material. Tests were performed at room temperature and elevated temperature. Surface of the sample was compared visually before and after exposure to 3.5% NaCl solution and results of experiment were presented in the form of diagrams (potentiostatic curves), indicating corrosion parameters - corrosion potential, polarization resistance and corrosion rates. At the end of this paper, comparison of results after performance of experiment at room and elevated temperatures were given and furthermore, conclusion was made