Smart coatings for corrosion protection of the construction materials

Korozija povzroča degradacijo kovinskih materialov, ki so v stiku s tekočino ali plinom. Sam proces se pospeši z izpostavitvijo visokim temperaturam, kislinam in solem. Posledično se spremenijo lastnosti materiala in nastaja škoda pri samem tehnološkem procesu. Da bi korozijo upočasnili, uporabljamo različna inhibitorna sredstva, ki so lahko organske ali anorganske narave. Diplomsko delo prikazuje študijo pametnih prevlek kot zaščito pred korozijskimi procesi na kovinski površini. Prevleka vsebuje inkapsuliran inhibitor, ki se sprosti, ko se nahaja v agresivnem okolju. Njegovo delovanje lahko zapolni poškodbe na prevleki, ki nastanejo ob fizični poškodbi, ob spremembi pH na medfazni površini med prevleko in korozivnim medijem ter podobnim. Ovojnica kapsule se ob tem predre, sprošča se inhibitor, ki se običajno adsorbira na površino in na tak način nudi dodatno zaščito pred korozijo. Uporabili smo vzorce iz aluminijeve zlitine tipa EN AW 6451 in jih predhodno obdelali tako, da je bila oprijemljivost prevleke iz epoksidne smole z inkapsuliranimi delci inhibitorja čim večja. Zaščitni sloj smo nanesli z metodo \u27spin coatinga\u27, ki ustvari enakomerno tanek sloj zaščitne prevleke na površini preiskovanega vzorca. Testirane prevleke so vsebovale tri različne koncentracije inkapsuliranih delcev inhibitorja. Največjo inhibicijsko učinkovitost je imela \u27pametna prevleka\u27 z najvišjim utežnim odstotkom inkapsuliranih delcev, ki so vsebovali kationski surfaktant. Za korozivni medij smo uporabili vodno raztopino natrijevega klorida z dvema različnima koncentracijama (3,5 % in 0,1 mol/L). Meritve smo izvedli na vzorcih po 30-minutni stabilizaciji v raztopini na mirovnem potencialu in po 48 urni predhodni izpostavitvi korozivnemu okolju. V posameznih primerih smo dosegli tudi najvišjo možno vrednost inhibicijske učinkovitosti in sicer = 99 % - 100 % .Corrosion presents a process that causes degradation of metal, when it comes into contact with liquid or gases. The process accelerates with exposure to high temperature, acidic solvents and salts. Chemical deterioration of a material leads to technological problems. Therefore, various inhibitors (organic or inorganic) are used for corrosion protection. This thesis presents the study of smart coatings for corrosion protection of metal materials. The coating contains an encapsulated inhibitor, which is released in contact with the agressive medium. Its activation can fill the gaps on the surface coating. The flaws in the coating can be caused by many factors, e.g. a physical injury, changed pH at the contact of the metal with the corrosive environment. Nanocapsules are able to detect active corrosion and release the inhibitor that increases corrosion protection. Aluminium based metalic substrates (EN AW 6451) were used in the experiments, which were previously processed for better adhesion of epoxy coating with nanocapsules containing the corrosion inhibitor. Spin coating was employed to apply the smart coating onto the metal surface. Tested coatings were prepared using three different concentrations of encapsulated cationic surfactant. The best inhibition efficiency was exhibited by the smart coating with the highest mass fraction of nanocapsules within the mixture. A water solution of sodium chloride with two different concentrations (3,5 % and 0,1 mlol/L) was used as corrosive medium. Tests were performed after 30 minute stabilisation of the sample in the solution and after 48 hour exposure to the corrosive environment. The applied smart coatings show a high potential fort he use as an efficient corrosion protection