Utjecaj strukture filma organske kiseline na djelotvornost korozijske zaštite

master's thesis

• Title (english): The influence of the structure of organic acid film on corrosion protection efficiency
• Author: Mario Petričević
• Mentor: Helena Otmačić Ćurković (mentor)
• Committee member: Helena Otmačić Ćurković (predsjednik povjerenstva)
• Committee member: Marijana Kraljić Roković (član povjerenstva)
• Committee member: Juraj Šipušić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2018-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

Cilj ovog rada bio je pripremiti i karakterizirati različite strukture filmova stearinske kiseline na oksidiranoj metalnoj površini te ispitati u kolikoj mjeri nastali filmovi štite metale nehrđajući čelik i leguru bakra i nikla od korozijskog djelovanja simulirane morske vode. Prednost primjene samoorganizirajućih slojeva, koji se formiraju adsorpcijom iz otopina dugolančanih organskih kiselina na površinu oksidom prekrivenog metala je ta što nemaju štetan utjecaj na okoliš i potreban je mali utrošak kemikalija čime je moguća jeftinija zaštita. Metodom uranjanja u otopinu stearinske kiseline, na metalnim površinama pripremljeni su debeli film i monosloj. Kako bi se formirao debeli film, korištena je otopina veće koncentracije (10^-2 M) a vrijeme adsorpcije je iznosilo 10 dana, dok je za formiranje monosloja korištena otopina niže koncentracije (10^-4 M) i trajanje adsorpcije iznosilo je 5 sati. Osim različitih uvjeta formiranja filmova, praćen je i utjecaj hrapavosti površine pri čemu su metalne površine brušene brusnim papirima finoće 80 i 2500 te polirane glinicom do zrcalnog sjaja. Pripremljeni uzorci podvrgnuti su elektrokemijskim ispitivanjima elektrokemijske impedancijske spektroskopije i Tafelove ekstrapolacije. Osim elektrokemijskih ispitivanja, provedena je pretražna elektronska mikroskopija, goniometrija i Fourier transformacijska infracrvena spektroskopija, kako bi se ispitale površinske karakteristike. Dobiveni rezultati ukazuju na to da deblji filmovi nude bolju korozijsku zaštitu od monoslojeva pri čemu velik utjecaj ima hrapavost površine.

Abstract (english)

The aim of this work was to prepare and characterize stearic acid films on the oxidized metal surface and to examine how efficiently these films protect stainless steel and copper and nickel alloy from the corrosion in simulated seawater. The advantage of the use of selfassembled layers formed by adsorption from long-chain organic acids on the surface of oxidecovered metal is that they do not have a harmful impact on the environment and requires a small amount of chemicals to be used, thus providing cheaper protection. A thick film and a monolayer were prepared on metal surfaces by immersion in a solution of stearic acid. To form a thick film, a higher concentration solution (10^-2 M) was used and the adsorption time was 10 days, while a lower concentration solution (10^-4 M) was used for the formation of the monolayer and the duration of adsorption was 5 hours. In addition to the different film forming conditions, the surface roughness impact was observed, with the metal surfaces being grinded with 80 and 2500 grinding papers and polished with alumina to mirror gloss. The prepared samples were subjected to electrochemical tests by electrochemical impedance spectroscopy and Tafel extrapolation. In addition to electrochemical testing, scanning electron microscopy, goniometry and Fourier transformational infrared spectroscopy were performed to investigate surface characteristics. The obtained results indicate that thicker films offer better corrosion protection than monolayers, with surface roughness having a great impact.

• Keywords: nehrđajući čelik; legura bakar nikal; korozija; samoorganizirajući slojevi; stearinska kiselina; morska voda; hrapavost; elektrokemijska ispitivanja
• Keywords (english): stainless steel; copper nickel alloy; corrosion; self-assembled layers; stearic acid; seawater; roughness; electrochemical testing
• Language: croatian
• URN:NBN: urn:nbn:hr:149:036387
• Study programme: Title: Materials Science and Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-07-16 13:26:14