scholarly journals Properties of Passive Films Formed on Ferrite-Martensite and Ferrite-Pearlite Steel Microstructures

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 594
Author(s):  
Aytac Yilmaz ◽  
Can Ozkan ◽  
Jilt Sietsma ◽  
Yaiza Gonzalez-Garcia

The effect of ferrite-pearlite and ferrite-martensite phase combinations on the passive layer properties of low carbon steel is investigated in a 0.1 M NaOH solution. Heat treatments were designed to obtain ferrite-pearlite and ferrite-martensite microstructures with similar ferrite volume fractions. Potentiostatic polarisation and electrochemical impedance spectroscopy (EIS) results demonstrated the lower barrier properties of passive films on ferrite-martensite microstructure compared to the ones formed on ferrite-pearlite microstructure. This was attributed to the higher donor density of the passive layer on ferrite-martensite samples, measured with Mott–Schottky analysis. This behaviour was explained by the complex microstructure morphology of the martensite phase that led to the formation of a more defective passive film.

1985 ◽  
Vol 38 (8) ◽  
pp. 1133 ◽  
Author(s):  
BG Pound ◽  
MH Abdurrahman ◽  
MP Glucina ◽  
GA Wright ◽  
RM Sharp

The corrosion rates of low-carbon steel, and 304, 316 and 410/420 stainless steels in simulated geothermal media containing hydrogen sulfide have been measured by means of the polarization resistance technique. Good agreement was found between weight-loss and polarization resistance measurements of the corrosion rate for all the metals tested. Carbon steel formed a non-adherent film of mackinawite (Fe1 + xS). The lack of protection afforded to the steel by the film resulted in an approximately constant corrosion rate. The stainless steels also exhibited corrosion rates that were independent of time. However, the 410 and 420 alloys formed an adherent film consisting mainly of troilite ( FeS ) which provided only limited passivity. In contrast, the 304 and 316 alloys appeared to be essentially protected by a passive film which did not seem to involve an iron sulfide phase. However, all the stainless steels, particularly the 410 and 420 alloys, showed pitting, which indicated that some breakdown of the passive films occurred.


MRS Advances ◽  
2017 ◽  
Vol 2 (62) ◽  
pp. 3909-3915
Author(s):  
Héctor M. Barbosa Cásarez ◽  
Araceli Espinoza Vázquez ◽  
Francisco J. Rodríguez-Gomez

AbstractPhenylcoumarin glucoside (4-PC) is a compound extracted from the plant Hintona latiflora and was studied as inhibitor for AISI 1018 steel corrosion in 3% NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques, which may find application as eco-friendly corrosion inhibitors. The 4-PC provides inhibitor properties that protect AISI 1018 low carbon steel against corrosion at low concentrations (5 ppm) obtained by EIS. Polarization studies showed that the inhibitor was of mixed type. The inhibition efficiency by the two electrochemical techniques shows similar results. The inhibitor adsorption was demonstrated to be a combined process (physisorption and chemisorption) according to the Langmuir isotherm.


2009 ◽  
Vol 79-82 ◽  
pp. 1017-1020 ◽  
Author(s):  
Hui Shu Zhang ◽  
Dong Ping Zhan ◽  
Song Lian Bai ◽  
Zhou Hua Jiang

The corrosion behaviors of Al-Si-Cr-Cu bearing low carbon steel and a reference steel Q235 were tested in a cyclic dry/wet environment containing 0.01mol/L NaHSO3 in laboratory. Rust layers were observed by optical microscope (OM), scanning electron microscopy (SEM) and XRD. The electrochemical behaviors of the steels were studied on the polarization curves and electrochemical impedance spectroscopy (EIS). The results indicate that after 120h corrosion test, the annual corrosion rates of the designed steels reduce 42 % than Q235 at least. The corrosion products are generally iron oxyhydroxides and oxides such as FeOOH, γ-FeOOH, α-FeOOH, γ-Fe2O3, Fe3O4. The α-FeOOH possesses good stabilization mainly exits and can improve the corrosion resistance. There are the enrichments of Cu, Cr, Si and Al in the rust layer close to the matrix, which make the rust layer be more compact and protected. The corrosion currents of the two designed steels are lower than that of Q235, the corrosion potentials are higher than that of Q235 after Tafel fitting. The rust layer impedances of the designed steels are higher than that of Q235.


2013 ◽  
Vol 686 ◽  
pp. 244-249 ◽  
Author(s):  
Poovarasi Balan ◽  
Aaron Ng ◽  
Chee Beng Siang ◽  
R.K. Singh Raman ◽  
Eng Seng Chan

Chromium pre-treatments of metal have been replaced by silane pre-treatments as more environmental friendly option. Nanoparticles can be added in the silane sol-gel network have been reported to improve corrosion resistance. In this work, the electrochemical corrosion resistance of low carbon steel coated with hybrid organic-inorganic sol-gel film filled with nanoparticles was evaluated. The sol-gel films have been synthesized from 3-glycidoxy-propyl-trimethoxy-silane (3-GPTMS) and tetra-ethyl-ortho-silicate (TEOS) precursors. These films have been impregnated with 300 ppm of silica or alumina nanoparticles. The electrochemical behavior of the coated steel was evaluated by means of electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Equivalent circuit modeling, used for quantifying the EIS measurements showed that sol-gel films containing silica nanoparticles improved the barrier properties of the silane coating. The silica nanoparticle-containing films showed highest initial pore resistance over the five days of immersion in 0.05M NaCl.


2020 ◽  
Vol 1012 ◽  
pp. 401-406
Author(s):  
Carlos Trivellato de Carvalho Filho ◽  
Pedro Paiva Brito

In the present work, the friction surfacing process was applied to manufacture aluminum alloy (AA6351) coatings on low carbon steel (AISI 1020) substrates. After friction surfacing the AA6351 deposited coatings were submitted to two finishing process in order to adjust surface roughness: milling and milling followed by sanding. The corrosion behavior of the two finishing process was compared with the as-deposited condition in order to determine the influence of surface roughness on the corrosion resistance of friction surfacing coatings. The corrosion behavior was examined by electrochemical impedance spectroscopy and potentiodynamic polarization in a 3.5wt.%NaCl solution containing naturally dissolved O2. The results obtained indicated that the elevated surface roughness observed in the as-deposited condition led to relatively lower corrosion resistance in comparison, with lower values for polarization resistance and more anodic corrosion potential.


2010 ◽  
Vol 2010.46 (0) ◽  
pp. 249-250
Author(s):  
Jun OKITA ◽  
Mitsuo NOTOMI ◽  
Tetsunori HADA

2018 ◽  
Vol 4 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Nilesh S. Bagal ◽  
Vaibhav S. Kathavate ◽  
Pravin P. Deshpande

AbstractThe present study aims at deposition of zinc phosphate coatings on low carbon steel with incorporated nano- TiO2 particles by chemical phosphating method. The coated low carbon steel samples were assessed in corrosion studies using electrochemical impedance spectroscopy and potentiodynamic polarization techniques (Tafel) in 3.5% NaCl solution. Morphology and chemical composition of the coatings were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy in order to observe growth of coating. Significant variations in the coating weight, porosity and corrosion resistance were observed with the addition of nano- TiO2 in the phosphating bath. Corrosion rate of nano-TiO2 chemical phosphate coated samples was found to be 3.5 milli inches per year which was 3 times less than the normal phosphate-coated sample (8 mpy). Electrochemical impedance spectroscopy studies reveal reduction of porosity of nano-TiO2 phosphate coated samples. It was found that nano-TiO2 particles in the phosphating solution yielded uniform phosphate coatings of higher coating weight, fewer defects and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal phosphating bath).


2013 ◽  
Vol 67 (8) ◽  
Author(s):  
Pravin Deshpande ◽  
Sanket Vathare ◽  
Shashikant Vagge ◽  
Elena Tomšík ◽  
Jaroslav Stejskal

AbstractThe coaxial coating of multi-wall carbon nanotubes (MWCNT) with poly(aniline) (PANI) was synthesised and a paint was prepared containing conducting PANI-MWCNT composite. The corrosion protection performance was assessed by open circuit potential measurements, potentiodynamic polarisation, and electrochemical impedance spectroscopy. The corrosion rate of low-carbon steel coated with 1.5 mass % of PANI-MWCNT-based paint in 3.5 mass % sodium chloride solution was found to be 0.037 mm y−1, about 5.2 times lower than that of unpainted low-carbon steel and 3.6 times lower than that of epoxy painted steel.


2013 ◽  
Vol 67 (8) ◽  
Author(s):  
Prathamesh Deshpande ◽  
Meera Murali ◽  
Pravin Deshpande ◽  
Vidyanand Galphade ◽  
Mahendra More

AbstractConducting poly(o-anisidine) coatings were obtained on low carbon steel in aqueous oxalic acid solution by using the galvanostatic technique. The coatings were characterised by potential-time relations, UV-VIS absorption spectroscopy, scanning electron microscopy, and X-ray diffraction measurements. The electrochemical performance of coated steel electrodes was evaluated on the basis of galvanostatic charge-discharge performance and electrochemical impedance spectroscopy in 0.5 M H2SO4. Maximum charging current was found in the case of the coating obtained at a current density of 8 mA cm−2 for 600 s duration at the supply voltage of 0.5 V. The estimated capacitance of the coated steel electrode for charging is 42.67 mF and 7.2 mF for discharging. It was also found that there was an increase in capacitance as a function of supply voltage and the maximum value was obtained at 0.5 V. The study reveals the possibility of using conducting poly(o-anisidine)-coated low carbon steel from oxalic acid medium as supercapacitor electrode materials.


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