Vpliv prevlek iz Al2O3/SiO2, izdelanih po postopku sol-gel, na korozijsko zaščito jekla C45

Filipič, Žan (author), Nagode, Aleš (mentor), Kosec, Tadeja (comentor)

Postopek sol-gel je način priprave materialov iz raztopine. Tako izdelani materiali so lahko v obliki prahu, vlaken ali tankih plasti. Prednosti postopka so enostavna izdelava, nizka temperatura sinteze, poceni proizvodnja in lažja kontrola kemijske sestave. V okviru magistrske naloge smo po postopku sol-gel pripravili prevleke iz Al2O3 in SiO2 na vzorcih ogljikovega jekla C45. Tanke plasti sólov za izdelavo želenih prevlek smo na jeklo nanesli po postopku potapljanja. Sledilo je sušenje prevlek pri različnih temperaturah. Izdelali smo enoplastne prevleke iz Al2O3 in SiO2 ter večplastne kompozitne prevleke v različnih kombinacijah obeh sólov. Prevleke smo analizirali z vrstičnim elektronskim mikroskopom (SEM) in EDXS-analizatorjem kemijske sestave. Za podrobno preučitev vpliva izdelanih prevlek na korozijsko zaščito jekla C45 smo izvedli korozijske preiskave. Opravili smo meritve korozijskega potenciala, linearno polarizacijo, potenciodinamske meritve in elektrokemijsko impedančno spektroskopijo. Po končanih korozijskih testih je sledilo še makroskopsko slikanje korodiranih površin vzorcev. Prevleke iz SiO2 in kompozitne prevleke so bile homogene in brez razpok, prevleke iz Al2O3 so bile homogene, vendar večinoma razpokane. Na podlagi rezultatov je bilo ugotovljeno, da vse prevleke izboljšajo korozijsko odpornost jeklu C45. Z nanosom prevlek jeklu zvišamo korozijski potencial in znižamo gostoto korozijskega toka ter zmanjšamo obseg poškodb pri koroziji. Najboljše lastnosti dosežemo z nanosom sol-gel prevleke iz SiO2. Pri kompozitnih večplastnih prevlekah dosežemo boljše lastnosti z nanosom prevlek, če je prvi sloj iz SiO2.

• Language: Slovenian
• Keywords: sol-gel, prevleka SiO2, prevleka Al2O3, kompozitna prevleka, korozija.
• Work type: Master's thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-111640
• COBISS.SI-ID: 1846367
• Publication date in RUL: 06.10.2019

FILIPIČ, Žan, 2019, Vpliv prevlek iz Al2O3/SiO2, izdelanih po postopku sol-gel, na korozijsko zaščito jekla C45 [online]. Master’s thesis. [Accessed 24 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=111640

Secondary language

• Language: English
• Title: Effect of sol-gel prepared Al2O3/SiO2coatings on corrosion protection of C45 steel

Abstract

The sol-gel process is a way of preparing materials from a solution. The materials produced by sol-gel route can be in the form of powders, fibers or thin films. The advantages of the process are simple manufacturing, low synthesis temperature, low cost production and easier control of chemical composition. As a part of master's thesis, Al2O3 and SiO2 coatings were prepared using plain carbon C45 steel according to the sol-gel production route. Thin films of sóls for the desired coatings were applied to the steel by dip-coating method. This was followed by drying the coatings at different temperatures. Single-layer coatings of Al2O3 and SiO2, as well as multi-layered composite coatings with different combinations of both sóls were manufactured. The coatings were analyzed by scanning electron microscope (SEM) with attached EDXS detector. Corrosion tests were carried out to examine the effect of the sol-gel coatings on the corrosion protection of C45 steel in details. Corrosion potential measurements, linear polarization, potentiodynamic measurements and electrochemical impedance spectroscopy were performed. After the corrosion tests were completed, macroscopic imaging of the corroded surfaces of the samples was carried out. SiO2 coatings and composite coatings were homogeneous and free of cracks, while Al2O3 coatings were homogeneous but mostly cracked. Based on the results, all coatings were found to improve the corrosion resistance of C45 steel. Coating of steel surface increases the corrosion potential and lowers the corrosion current density and reduces the extent of corrosion damage. The best properties are achieved by applying a SiO2 sol-gel coating. For composite multilayered coatings, better properties are achieved by coating with the first layer of SiO2.

• Keywords: sol-gel, SiO2 coating, Al2O3 coating, composite coating, corrosion