The effect of addition of TiO2 nanoparticles on the wear and corrosion behavior of ceramic coatings applied on AZ31 magnesium alloy by plasma electrolytic oxidation

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: The effect of addition of TiO2 nanoparticles on the wear and corrosion behavior of ceramic coatings applied on AZ31 magnesium alloy by plasma electrolytic oxidation

ارائه دهنده: Provider: hanane mozafarnia

اساتید راهنما: Supervisors: Arash Fattah-Alhosseini (Ph.D)

اساتید مشاور: Advisory Professors: Meisam Nouri (Ph.D) , Omid ImanTalab (Ph.D)

اساتید ممتحن یا داور: Examining professors or referees: hasan elmkhah, hamid esfahani

زمان و تاریخ ارائه: Time and date of presentation: October, 13, 2021

مکان ارائه: Place of presentation: http://vc.basu.ac.ir/eng-thesis05/

چکیده: Abstract: In this study, a ceramic coating on AZ31 magnesium alloy was fabricated using a plasma electrolytic oxidation coating process in a phosphate based electrolyte containing different concentrations of TiO2 nanoparticles under direct pulsed current. One of the fixed components of the base electrolyte was hydroxyapatite particles which were precipitated by wet chemical precipitation. The coating process was performed at a frequency of 1000 Hz, current density of 1 A, duty cycle of 50% and time of 7 minutes. Then, the effect of different concentrations of TiO2 nanoparticles (0, 1, 2, 3 and 4 g / l ) in the base electrolyte on different properties of coatings such as microstructure, thickness, phase and element composition, surface roughness, surface wettability, corrosion behavior and wear behavior were investigated. Scanning electron microscopy (SEM) was used to study the microstructure and cross section of the coatings, X-ray diffraction (XRD) and X-ray energy diffraction (EDS) spectroscopy tests were used to study the chemical composition of the coatings, Electrochemical impedance spectroscopy (EIS) was used to study the electrochemical behavior of coatings and Pin On Disc test was used to study the wear behavior of coatings. The results showed that increasing the concentration of TiO2 nanoparticles in coatings changes the color of coatings to bold blue, increases the amount and size of porosity, increases the thickness of coatings, increases surface roughness and increases their wettability. XRD results showed that the coatings are mainly composed of Mg, MgO, Mg3 (PO4) 2, Mg2TiO4 and HA phases. The results of corrosion resistance of coatings in body simulation solution (SBF) showed that increasing the concentration of TiO2 nanoparticles from 1 to 4 g / l in coatings leads to a decrease in corrosion resistance of coatings. Also, the effect of immersion time of coatings for three days showed that increasing the immersion time in all coatings increases the corrosion resistance, which is due to the filling of pores with corrosion products and the growth of hydroxyapatite. The results of wear test showed that the wear rate of coatings with increasing concentration of TiO2 nanoparticles from 1 to 4 g / l has a decreasing trend at first and then an increasing trend. This is due to the increase in hardness of the coatings with increasing concentration of TiO2 nanoparticles, which reduces the wear rate at first, but with further increase in the concentration of TiO2 nanoparticles due to increased roughness, friction increases and as a result the wear rate increases. According to the results, the sample containing 1 g / l of TiO2 nanoparticles, in addition to corrosion resistance, also showed resistance in the wear test, and as a result, this sample was selected as the optimal sample

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