Inhibicija korozije aluminijeve zlitine z dodatkom vanadata in molibdata v kloridno raztopino

Pavlovčič, Tjaša (author), Tomšič, Matija (mentor), Milošev, Ingrid (co-mentor)

Aluminij in njegove zlitine so zaradi svojih dobrih mehanskih in kemijskih lastnosti eden izmed najpomembnejših tehnoloških materialov. V letalski industriji in v gradbeništvu se pogosto uporablja aluminijeva zlitina AA2024. Njena mikrostruktura je zelo kompleksna in sestavljena iz veliko intermetalnih delcev. Zlitina je podvržena jamičasti in interkristalni koroziji. V magistrskem delu je predstavljena protikorozijska zaščita te zlitine z vanadatnimi in molibdatnimi ioni. Preučevana inhibitorja sta bila v korozijski medij, 0,1 M raztopino NaCl, dodana v različnih koncentracijah od 0,5 mM do 250 mM. Natrijev vanadat je skoraj pri vseh koncentracijah občutno znižal gostoto korozijskega toka, medtem ko je natrijev molibdat pri visokih koncentracijah občutno vplival na povečanje razlike med korozijskim potencialom in potencialom preboja, kar pomeni večjo odpornost proti lokalni koroziji. Za ta inhibitorja ni bilo mogoče opaziti sinergijskega inhibicijskega efekta. Preučevali smo tudi vpliv časa potopitve aluminijeve zlitine v raztopino NaCl z dodatkom inhibitorja in vpliv pH vrednosti na potek njene korozije. Pri obeh inhibitorjih je pri dolgotrajnejši stabilizaciji prišlo do izboljšanja korozijskih parametrov. Natrijev vanadat inhibicijsko najbolje deluje v nevtralnem in šibko bazičnem, natrijev molibdat pa v šibko bazičnem mediju. S tehnikami površinske analize je bila na površini aluminijeve zlitine potrjena tvorba spojin na osnovi molibdena in vanadija.

• Language: Slovenian
• Keywords: aluminijeva zlitina, korozija, inhibitorji, vanadij, molibden
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-117364
• COBISS.SI-ID: 22881027
• Publication date in RUL: 08.07.2020

Secondary language

• Language: English
• Title: Corrosion Inhibition of aluminium alloy in chloride solution by vanadate and molybdate

Abstract

Aluminium and aluminium alloys are due to their good mechanical and chemical properties most commonly used technological material. The AA2024 aluminium alloy is used widely in aircraft structures and design. Its microstructure is very complex and composed of numerous intermetallic particles. The alloy is susceptible to pitting and intergranular corrosion. This study addresses the corrosion protection of AA2024 alloy with vanadate and molybdate as corrosion inhibitors. These compounds were added to the corrosion medium, 0.1 M NaCl solution, at various concentrations from 0.5 mM to 250 mM. Sodium vanadate significantly reduced the corrosion current density at almost all concentrations, while sodium molybdate at higher concentrations significantly increased the difference between the corrosion potential and breakdown potential. No synergistic effect was observed for these two inhibitors. The influence of immersion time and the influence of the pH value on the corrosion behaviour were also examined. With both inhibitors, the corrosion parameters were improved with increasing immersion time under the conditions of open circuit. Sodium vanadate inhibits corrosion best in neutral and mild basic medium and sodium molybdate in mild basic medium. The formation of molibdenum and vanadium compounds was confirmed on the surface of aluminium alloy by surface analysis techniques.

• Keywords: aluminium alloy, corrosion, inhibitors, vanadium, molybdenum