Analysis of amines on steel

V magistrskem delu smo preučevali učinkovitost inhibicije osmih izbranih aminov, in sicer 2-etil-heksil-amina, anilina, benzilamina, butilamina, etilamina, izopropilamina, oktilamina in trietanolamina kot potencialne korozijske inhibitorje. Poskuse smo izvedli na nizko legiranem jeklu C15, pri čemer smo korozijski inhibitor dodajali v raztopino korozivnega medija. Potopitvene preskuse smo izvedli pri dveh temperaturah: sobni (25 °C) in pri 70 °C. Z elektrokemijskimi meritvami smo nadaljevali le pri sobni temperaturi. Za najučinkovitejše molekule smo izvedli še meritve s 3D-profilometrom, meritve omočitvenega kota in FTIR-analizo. Kot korozivni medij smo izbrali 3-odstotno raztopino NaCl. Amine smo dodajali v dveh različnih utežnih deležih, prvi (nižji) je bil 0,1 % in drugi (večji) 1,0 %. Za izboljšanje inhibicije smo preskusili tudi, kakšen učinek ima na korozijo dodatek jodidnih ionov. V ta namen smo korozivnemu mediju z in brez korozijskega inhibitorja dodali KI. Tudi pri tem smo uporabili dva različna utežna deleža dodatka KI – 0,5 in 1,0 %. Vse vzorce smo pripravljenim raztopinam pustili izpostavljene 72 ur. Nadalje so uporabili različne elektrokemijske metode: kronopotenciometrične meritve, meritve polarizacijske upornosti in potenciodinamske meritve. Prvi dve metodi sta potekali 10 ur, medtem ko smo potenciodinamske meritve izvedli po 10 urah, pri sobni temperaturi, z obema koncentracijama aminov in 0,5-odstotnim dodatkom KI. Na podlagi rezultatov potopitvenih preskusov smo določili učinkovitost inhibicije, korozijsko hitrost in sinergistični parameter. Ugotovili smo, da na učinkovitost posameznega amina vpliva koncentracija, temperatura in v manjši meri tudi dodatek KI. Najvišjo učinkovitost inhibicije (61,57 %) smo dosegli z dodatkom 1,0 % izopropilamina pri 70 °C. S pomočjo potenciodinamskih krivulj smo ugotovili, da pri višji koncentraciji aminov (1,0 %) prevladuje mešani tip korozijskih inhibitorjev. Z rezultati površinske analize smo na koncu dobili podatke o razliki med vzorcem v neinhibirani raztopini in vzorcem v inhibirani raztopini, s čimer potrjujemo adsorpcijo aminov na površino jekla C15.The purpose of the master’s thesis was to study the inhibition efficiency of 8 chosen amines. Those are: 2-ethylhexyl amine, aniline, benzylamine, butylamine, ethylamine, isopropylamine, octylamine, three ethanolamine. The experiments were performed on alloy steel C15, wherein the inhibitor was added directly in the solution of the corrosive medium. The immersion tests were performed at two temperaturesroom temperature (25 °C) and at 70 °C, the electrochemical measurements were continued only at room temperature. For the most-efficient molecules, we performed additional measurements with the 3D-profilometer, measurements of the contact angle and FTIR-analysis. The chosen corrosive medium was a 3 % solution of NaCl. Amines were added in two different weight shares, the first, lower, was 0.1 % and the second, higher, was 1.0 %. For the improvement of the inhibition, we also tested the effects of adding iodine ions, on the corrosion. For this purpose, we added Potassium iodide to the corrosive medium with and without the inhibitor. We also used two different concentrations of KI, these were 0.5 and 1.0 %. All the samples were exposed to the prepared solutions in 72 hours. Electrochemical measurements were performed for 10 hours only at room temperature, with both concentrations of amines and a lower concentration (0.5 %) of the additive KI. With the results of the immersion tests, we determined the inhibition efficiency, corrosion rate, and the synergistic parameter. We found out that the efficiency of a single amine is affected by the concentration, temperature and (in a smaller amount) also the addition of KI. The highest inhibition efficiency (61.57 %) was achieved with addition of 1.0 % of isopropylamine at 70 °C. Depending on the potentiodynamic curves, we can claim that inhibitors of the mixed type prevail at higher concentrations. With the results of the surface analysis at the end, we confirmed the difference between the sample in the uninhibited and the sample in the inhibited solution and we confirmed adsorption of amines on the steel surface