Electrochemical oxidation of aluminium

Sve većim napretkom industrije dolazi do sve većih zahtjeva za materijale, aluminij kao drugi najzastupljeniji materijal mora odgovarati tim zahtjevima. Potreba za sve boljim mehaničkim i fizikalnim svojstvima aluminija rezultira sve većim brojem legura istoga. Važno svojstvo aluminija je njegovo stvaranje oksidne prevlake koja ga štiti od korozije, ta prevlaka može biti stvorena i umjetnim putem odnosno elektrokemijskom oksidacijom. Prevlaka nastala elektrokemijskom oksidacijom je mnogostruko djelotvornija u zaštiti aluminija od korozije od one nastale prirodnim putem. Kako bi korozijska postojanost te prevlake bila što veća aluminij se podvrgava brojnim istraživanjima, u kojima se različitim tehnikama i dodacima pokušava dobiti što bolja zaštitna svojstva oksidne prevlake. Rad se sastoji od dva dijela teorijskog i eksperimentalnog. Teorijski dio rada objašnjava podjelu legura aluminija kao i njihova svojstva, korozijsku postojanost i primjenu. Navedene su metode zaštite aluminija te je detaljno objašnjena zaštita aluminija oksidnim prevlakama odnosno elektrokemijskom oksidacijom. Eksperimentalni dio je obuhvatio pripremu uzoraka od aluminija podijeljenu na dva djela. Jedan dio uzoraka je elektrokemijski oksidiran u elektrolitima s različitim koncentracijama cerija dok drugi dio uzoraka je uronjen u otopinu s različitom koncentracijom cerija u cilju ispitivanja inhibitorskog djelovanja. Na uzorcima su zatim provedena metalografska i elektrokemijska ispitivanja.With industry growing, demands for better material properties are increasing, aluminum as the second most representative material must meet these requirements. The need for the better mechanical and physical properties of aluminum results in an increasing number of aluminium alloys. An important feature of aluminum is its formation of an oxide coating that protects it against corrosion, this coating can be created by artificial means or by electrochemical oxidation. The coating made by electrochemical oxidation is more effective in protecting aluminum from corrosion than the natural made one. Aluminum is subjected to numerous studies in order to increase corrosion resistance of this coating, in witch various techniques and additives are tried to obtain the best protective properties of the oxide coating. This research contains two parts, the theoretical and experimental. The theoretical part of the paper explains the division of aluminum alloys as well as their properties, corrosion resistance and application. Aluminum protection methods are outlined and aluminum protection with oxide coatings or electrochemical oxidation is explained in detail. The experimental part included the preparation of aluminum samples divided into two pieces. One part of the samples was electrochemically oxidized in electrolytes with different cell concentrations while the second part of the sample was immersed in a solution with a different concentration of the cerium in order to investigate the inhibitory activity. The samples were then subjected to metallographic and electrochemical tests