Ocjena djelotvornosti zaštitnih premaza in situ elektrokemijskim mjerenjima

undergraduate thesis

• Title (english): Assessment of protective coating efficiency by in situ electrochemical measurements
• Author: Dino Bubaš
• Mentor: Sanja Martinez (mentor)
• Committee member: Sanja Martinez (predsjednik povjerenstva)
• Committee member: Lidija Furač (član povjerenstva)
• Committee member: Marijana Kraljić Roković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2015-09-17, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Basic Technical Sciences; Materials

Abstract

U ovom je radu metoda elektrokemijske impedancijske spektroskopije primijenjena na šest različitih visokootpornih premaza korištenjem dvije elektrokemijske ćelije različitih konstrukcija od kojih je jedna pogodnija za primjenu u laboratoriju, a druga za mjerenja in situ. Rezultati dobiveni dvjema eksperimentalnim i dvijema računskim strategijama obrađeni su statistički te međusobno uspoređeni.
Numeričke vrijednosti električnih svojstava premaza dobivene su izravnim očitanjem otpora pri 0.1 Hz i kapaciteta pri 100 Hz u slučaju obje ćelije i preciznije, matematičkim modeliranjem, samo u slučaju velike ćelije. Impedancijski rezultati za malu ćeliju razlikuju se od onih u velikoj po većem rasipavanju mjernih točaka u niskofrekventnom području što modeliranje rezultata male ćelije čini nemogućim.
Dobiveno je izvrsno slaganje modeliranih kapaciteta i izravno očitanih kapaciteta za veliku ćeliju (r^2=0.997), te nešto lošije za malu ćeliju (r^2=0.834). Modelirani otpori veći su od izravno očitanih jer predstavljaju ekstrapolaciju ponašanja elektrode u područje istosmjerne struje. Primijeni li se kriterij ocjene premaza na osnovu otpornosti pri 0.1 Hz, svi su ispitivani premazi izvrsnih zaštitnih svojstava (> 1 GΩ cm^2), a s pomoću obje ćelije mogu se razlučiti najlošiji, tamno sivi (≈ 9 i 6 GΩ cm^2) i najbolji, bijeli (≈ 153 i 59 GΩ cm^2) premaz. Redoslijed djelotvornosti zaštitnih premaza s otpornošću unutar istog reda veličine nemoguće je pouzdano razlučiti. Ipak, zbog kriterija ocjene premaza koji se za pojedinu ocjenu proteže unutar 1.5 do 2 reda veličine, može se zaključiti da primjena male ćelije daje prihvatljive rezultate za mjerenja na objektima in situ.

Abstract (english)

In this work, the method of electrochemical impedance spectroscopy is applied on six different high impedance coatings using two electrochemical cells of different construction, of which one is more suitable for laboratory usage, whereas the other one for measurements in situ. The given results from two experimental and two computational strategies are processed statistically and mutually compared.
Numeric values of electrical properties of coatings were given by direct reading of the impedance on 0.1 Hz and the capacitance on 100 Hz for both cells, and by mathematical modeling for the big cell. The impedance results for the small cell differ from the ones in the big one in greater dissipation of measured points in low frequency range, which in turn makes results modeling of the small cell impedance results impossible.
There is an excellent correlation of modulated capacitances and the directly read capacitances for the big cell (r^2=0.997), and the correlation is lower for the small cell (r^2=0.834). Modelled impedances are higher than the ones directly read because they represent the extrapolation of the electrode behavior in the DC range. If the evaluation coating criteria is applied based on 0.1 Hz impedance, all tested coatings have excellent protective properties (> 1 GΩ cm^2), and by both cells the worst coating, the dark grey one (≈ 9 and 6 GΩ cm^2), and the best coating, the white one (≈ 153 and 59 GΩ cm^2) can be distinguished. The efficiency of protective coatings having impedance within the same order of magnitude is impossible to do for certain. However, because of the evaluation coating criteria which for individual rating spreads within 1.5 up to 2 order of magnitude, it can be concluded that applying the small cell provides acceptable results for measurements on objects in situ.

• Keywords: korozija; premaz; elektrokemijska impedancijska spektroskopija
• Keywords (english): corrosion; coating; electrochemical impedance spectroscopy
• Language: croatian
• URN:NBN: urn:nbn:hr:149:363946
• Study programme: Title: Applied Chemistry - Undergraduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Environmental chemistry and green technologies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2016-11-29 16:22:32