20.500.12556/RUL-150251 Vpliv organskega inhibitorja in pH na korozijo bakrovih zlitin Effect of organic inhibitor and pH on corrosion of copper alloys Moderna tehnologija in udobje narekujeta tudi sodobne materiale, ki izkazujejo različne mehanske lastnosti in korozijsko obstojnost. Zaradi želje po zmanjšanju stroškov se pogosto poslužujemo rešitev, ki morda niso primerne za dano aplikacijo in dolgoročno uporabo. Posledično se lahko na izdelkih pojavijo korozijske poškodbe. Korozija je razdiralni napad na kovino, pri čemer se le-ta vrača v energijsko bolj ugodno stanje. Ob tem se tvorijo različne spojine, kot so na primer oksidi. Na potek procesa korozije vpliva predvsem okolje oziroma prisotnost korozijskega medija, ter razlika v elektrokemijskem potencialu na površini kovine. Že prisotnost vlage v ozračju lahko predstavlja korozijski medij za kovine. Ker se koroziji težko izognemo, je pri načrtovanju kovinskih izdelkov veliko pozornosti namenjene protikorozijski zaščiti. Obstajajo različne vrste protikorozijskih zaščit, pri čemer se najpogosteje uporablja nanos manj ali bolj reaktivne kovine, organske in anorganske prevleke, dodatek zaviralcev korozije (t. i. inhibitorjev) ali zaščita z zunanjim potencialom. Pri nekaterih kovinah in zlitinah dodatna zaščita površine ni potrebna, saj se pod vplivom okolja na površini tvorijo pasivne plasti ali patine. Pogoj za nastanek oksidne plasti ali patine je prisotnost elementov v zlitini, ki tvorijo tovrstne spojine (npr. baker in cink). Zlitinski elementi med ohlajanjem taline tvorijo različne faze, katerih prisotnost v trdnem stanju je odvisna od kemijske sestave. Za določanje prisotnih faz v izbranih zlitinah smo si pomagali z izrisom faznih diagramov. O primernosti materiala, oziroma njegovi odpornosti na okoljske vplive, se odločamo na podlagi korozijskih testov v realnem okolju. Tovrstni testi so večinoma dolgotrajni in nam izkazujejo le povprečje realnega stanja. Zato je hitreje in bolj učinkovito, če korozijske teste predhodno izvedemo v laboratorijskem okolju z elektrokemijskimi te- stiranji v agresivnem mediju kot je na primer raztopina natrijevega klorida. S primerja- vami različnih elektrokemijskih testov lahko ocenimo kateri materiali izpolnjujejo pred- pogoje za določeno aplikacijo ter se na podlagi le-teh odločimo za najprimernejše te- ste v realnem okolju. Naloga obravnava elektrokemijske študije na vzorcih bakra in bakrovih zlitin baker-nikelj, baker-cink in baker-nikelj-cink, ki so nepogrešljivi materiali v širokem spektru aplikacij. V nalogi so predstavljeni vplivi različnih vrednosti pH raz- topine natrijevega klorida na korozijsko obstojnost teh materialov. Kot način protikoro- zijske zaščite je bil preizkušen dodatek organskega inhibitorja 2-merkaptobenzimida- zola, ki se je izkazal kot učinkovit ne le za baker ampak tudi bakrove zlitine. Za baker in bakrove zlitine je značilno, da na zraku s časom tvorijo patino. Delovanje korozij- skega inhibitorja je bilo zato preizkušeno tudi na površinah, ki so bile modificirane z dvema različnima vrstama patine. With tendency towards new technologies and comfort, we often cross-paths with different materials and their unique mechanical properties and corrosion stability. And while reducing costs is commendable, there are cases where cost reductions happen at the expense of long-term solution. As a result, we often witness corrosion induced defects and material failure. Corrosion is a spontaneous process, where metal transforms back to thermodynamically efficient state, which is usually in a form of oxides. The rate of corrosion process is a direct result of environment and corrosion media, as well as electrochemical potential of given metal. Even the presence of humidity in atmosphere is considered as a corrosion medium for metals. Although corrosion process is inevitable to some degree, we can still slow down the progression or, in some cases, stop it completely. In order to do so, we can use many different corrosion protection approaches, such as organic and inorganic protection layers, layer of less or more reactive metals, by imposing potential onto metal or adding corrosion inhibitors in a surrounding medium, i. e., electrolyte. While most of metals and alloys are susceptible to material failure due to corrosion, some form a passive surface layer and patinas that serves as a protection against further damage. Since corrosion tests require long-term exposure to elements, we often conduct preliminary laboratory tests. These tests can be considered as simulations and help to determine the course and setup of subsequent testing in actual environment. Therefore, it is faster and more efficient if the corrosion tests are previously carried out in a laboratory environment with electrochemical tests in an aggressive medium such as sodium chloride solution. By comparing different electrochemical tests, we can assess which materials meet the prerequisites for a specific application and, based on these, decide on the most suitable tests in a real environment. This thesis deals with electrochemical studies on copper samples and copper-nickel, copper-nickel-zinc and copper-nickel-zinc copper alloys, which are indispensable materials in a wide range of applications. The effects of different pH values of the sodium chloride solution on the corrosion resistance of these materials were investigated. As a method of corrosion protection, the addition of the organic inhibitor 2-mercaptobenzimidazole was tested, which proved to be effective not only for copper but also for copper alloys. Copper and copper alloys typically to form a patina in the air over time. The performance of the corrosion inhibitor was therefore also tested on surfaces modified with two different types of patina. baker bakrove zlitine raztopina NaCl vpliv pH inhibitor patina copper copper alloys NaCl solution effect of pH value inhibitor patina true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2023-09-15 09:00:06 2023-09-15 09:00:12 2023-09-17 03:35:18 0000-00-00 00:00:00 2023 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 95762 18226.pdf 18226.pdf 1 2165753ABC633637CFA18D01CFAA1294 607519bc2f747e1e6f502aae62d9b1c177062e1385bcc1badd5c7ce901a86f17 84d8f0f0-5395-11ee-9ef6-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=174817 Naravoslovnotehniška fakulteta 0 0 0