Showing 45 results for Corrosion
M. Mohammadnejad, M. Ehteshamzadeh, S. Soroushian,
Volume 11, Issue 2 (6-2014)
Abstract
Microstructure and corrosion performance of admiralty brass (ADB) and aluminum brass (ALB) alloys after
passing different annealing heat treatments were investigated using optical and scanning electron microscope, energy
dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), DC polarization measurements and electrochemical
impedance spectroscopy (EIS). The results showed that heat treating of ALB caused gradient in aluminum
concentration across the grains whose increased with increasing of annealing temperature. On the other hand,
corrosion current density (i
corr) of ADB in 3.5%NaCl media decreased with increasing of recrystallization, while ALB
showed corrosion behavior inconsistent with ADB. The impedance measurements showed that corrosion rate of ADB
decreased with increasing of exposure time from 0 to 15 days which could be related to the formation of SnO
2
surface
film and the Sn-rich phases. While polarization resistance of ALB decreased by passing days in the corrosive media
which could be associated to establishing of differential aluminum concentration cells.
A. Nikfahm, I. Danaee, A. Ashrafi, M. R. Toroghinejad,
Volume 11, Issue 2 (6-2014)
Abstract
In this research accumulative roll bonding process as sever plastic deformation process was applied up to
8 cycles to produce the ultrafine grain copper. Microstructure of cycle 1, cycle 4 and cycle 8 investigated by TEM
images. By analyzing TEM images the grain size measured below 100 nm in cycle 8 and it was with an average grain
size of 200 nm. Corrosion resistance of rolled copper strips in comparing with unrolled copper strip was investigated
in acidic (pH=2) 3.5 wt. % NaCl solution. Potentiodynamic polarization and EIS tests used for corrosion resistance
investigations. The corrosion morphologies analyzed by FE-SEM microscopy after polarization test and immersion for
40 hours. Results show that the corrosion resistance decreased up to cycle 2 and increased after rolled for forth time.
The corrosion degradation was more intergranular in cycle 2 and unrolled counterpart. It was more uniform rather
than intergranular type in cycle 8. Corrosion current density in unrolled sample (2.55 µAcm
-2
) was about two times of
that in cycle 8 (1.45 µAcm
-2
). The higher corrosion rate in cycle 2 in comparison with others was attributed to unstable
microstructure and increase in dislocation density whereas the uniform corrosion in cycle 8 was due to stable UFG
formation
H. Safabinesh, A. Arab Fatideh, M. Navidirad, M. Ghassemi Kakroudi,
Volume 11, Issue 3 (9-2014)
Abstract
In order to improve the corrosion resistance of aluminosilicate refractories by molten aluminum, alkaline
fluoride NaF and cryolite Na3AlF6 powders were studied. Both physical and chemical properties are known to
influence wetting and corrosion behavior. This paper devoted to determine the influence of alkaline fluoride and
cryolite added to andalusite based castable on the reaction with aluminum alloys. These additives led to the in-situ
formation of celsian phases within the refractory matrix that led to improved corrosion resistance at 1300°C. Phase
analysis revealed that celsian formation suppressed the formation of mullite within refractories, thereby reducing
Penetration
M. Siadat-Cheraghi, S. R. Allahkaram, Z. Shahri,
Volume 12, Issue 1 (3-2015)
Abstract
Pure cobalt coatings were electrodeposited on copper substrate by means of direct electric current in a
chloride solution at different current densities in the range of 10-70 mA cm
-2
. The surface morphology and
microstructure were investigated via X-ray diffraction analysis and scanning electron microscopy. Corrosion behavior
of cobalt coatings was also studied in a 3.5 wt% NaCl solution using potentiodynamic polarization and impedance
spectroscopy techniques. The results showed that corrosion resistance of deposits was strongly influenced by the
coating’s morphology. Co deposit obtained in lower current densities exhibited the highest corrosion resistance, due
to their lower grain boundaries and so the least density of active sites for preferential corrosion attacks
A. Fattah-Alhosseini, M. Ranjbaran, S. Vajdi Vahid,
Volume 12, Issue 2 (6-2015)
Abstract
In this study, corrosion behaviour of A356-10 vol.% SiC composites casted by gravity and squeeze casting
is evaluated. For this purpose, prepared samples were immersed in HCl solution for 1h at open circuit potential. Tafel
polarization and electrochemical impedance spectroscopy (EIS) were carried out to study the corrosion resistance of
composites. The Tafel polarization and EIS studies of the corrosion behaviour of the A356-10 vol.% SiC composites
showed that the corrosion resistance of the composite casted by squeeze casting was higher than that of the composites
casted by gravity in selected corrosion media. Also, the Tafel polarization and EIS studies revealed that the corrosion
current densities of both composites increase with the increase in the concentration of HCl. The micrographs of
scanning electron microscope (SEM) clearly showed the squeeze casting composite exhibits a good dispersion/matrix
interface compared to that of the composites produced by gravity casting
J. Dahdele, I. Danaee, G. H. Rashed, M. Rashvandavei,
Volume 12, Issue 2 (6-2015)
Abstract
The inhibition behavior of N,N′-bis(2,4,6-trihydroxyacetophenone)-propandiimine (THAPP) as an
environmentally friendly Salen Ligand on the corrosion inhibition of mild steel was studied in alkaline solution
(pH=10) containing 3% NaCl. Measurements were carried out using electrochemical and surface techniques. The
experimental results suggested that this compound was an effective corrosion inhibitor for mild steel and the protection
efficiency was increased with the increase in inhibitor concentration. Polarization curves indicated that this organic
compound was a mixed-type inhibitor. Adsorption on the mild steel surface follows the Langmuir isotherm model.
Activation parameters and thermodynamic adsorption parameters of the corrosion process such as E
a
, ΔH, ΔS, K
ads
,
and ΔG
ads
were calculated by the obtained corrosion currents at different temperatures
S. Noori, J. Khalil-Allafi,
Volume 12, Issue 2 (6-2015)
Abstract
The effect of anodic oxidation of a NiTi shape memory alloy in sulfuric acid electrolyte on its surface
characteristics was studied. Surface roughness was measured by roughness tester. Surface morphology was studied
using optical microscopy (OM) and scanning electron microscopy (SEM). Corrosion behavior was specified by
recording Potentiodynamic polarization curves and measuring the content of Ni ions, released into a SBF solution
using atomic absorption spectroscopy (AAS). Fourier transformation infrared radiation (FT-IR) and energy dispersive
spectroscopy were employed to verify the biocompatibility of the anodized and bare alloys after submersion in SBF. It
was shown that anodic oxidation in sulfuric acid significantly increases corrosion resistance and biocompatibility. This
layer improves corrosion resistance and Ni ion-release resistance by impeding the direct contact of the alloy with the
corrosion mediums i.e. Ringer and SBF solutions. The TiO2 oxide layer also decreases the releasing of Ni ions in to
SBF solution
H. Nazemi, M. Ehteshamzadeh,
Volume 12, Issue 3 (9-2015)
Abstract
Compression springs were prepared from Cr-Si high strength spring steel and coated with pure Zn and ZnNi by electroplating process. The effect of baking after electroplating as well as applying an electroless nickel
interlayer on the fatigue and fatigue corrosion of the springs was investigated. The results were analyzed using weibull
statistical model. A considerable improvement (8%) in fatigue life of the electroplated springs with Zn-Ni was observed
in the presence of Ni interlayer. In addition, baking of these electroplated springs improved fatigue life by 4%. The
fatigue life under salt spraying conditions, however, has demonstrated remarkable reduction by 40%, 34% and 30%
for Zn-Ni plating, backed and unbaked Zn-Ni plating containing Ni interlayer, respectively
A. Mohsenifar, M. R. Aboutalebi, S. H. Aboutalebi,
Volume 12, Issue 3 (9-2015)
Abstract
Hot dip aluminizing was carried out on the low carbon steel rod under optimized conditions. The aluminized
samples were further oxidized at 1000̊C in air atmosphere at two different times of 20 and 60 minutes. Microstructure
study and phase analysis were studied by scanning electron microscopy and X-ray diffraction methods, respectively.
The characterization of the coating showed that, Fe2
Al5
has been the major phase formed on the surface of specimen
before heat treatment. Following the oxidation of the coating at high temperature, Al
2O3
was formed on the surface of
coating while Fe
2
Al5
transformed into FeAl and Fe
3
Al which are favorable to the hot corrosion resistance of the
coating. Corrosion resistance of aluminized samples before and after heat treatment was evaluated by rotating the
samples in the molten aluminum at 700 ̊C for various times and the dissolution rate was determined. The obtained
results showed that by oxidizing the coating at high temperature, the corrosion resistance of the samples in molten
aluminum improves significantly.
A. Qaed Amini Haroooni, H. Eskandari, M. H. Maddahy, I. Danaee,
Volume 12, Issue 4 (12-2015)
Abstract
The electrochemical behavior of 6063 aluminum alloy in ethylene glycol-water mixture was investigated by polarization curves and AC impedance measurements (EIS). The results obtained from polarization curves showed that corrosion rate decreased with increasing ethylene glycol concentration. EIS data showed the decrease in the interface capacitance which caused by adsorption of ethylene glycol at the surface of aluminum alloy. The cathodic current increased with the increase in rotating speeds of solution and the anodic current decreased. The effect of temperature was studied and the corrosion rate was increased with increasing the temperature. In addition, thermodynamic parameters were calculated in different ethylene glycol concentrations
N. Bahrami Panah, N. Ajami,
Volume 13, Issue 1 (3-2016)
Abstract
The epoxy coatings containing multi-walled carbon nanotube/ poly ortho aminophenol nanocomposite were prepared and used as anticorrosive coatings. The nanocomposites with different contents of carbon nanotube were synthesized in a solution of sodium dodecyl sulfate and ammonium peroxy disulfate as a surfactant and an oxidant, respectively. The morphology and structural properties were confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy methods. The mean size of nanocomposite particles was 20-35 nm determined by scanning electron microscopy. The epoxy coatings containing the nanocomposites were applied over mild steel panels and their corrosion performance was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization measurements in a 3.5 % sodium chloride solution. The results showed that epoxy coatings consisting of nanocomposite with 1 wt.% multi-walled carbon nanotube exhibited higher anticorrosive properties than other prepared coatings of different carbon nanotube contents, which could be due to the strong interaction between the mild steel surface and the conjugated nanocomposite.
M. R. Khorram, M. R. Shishesaz, Iman Danaee, D. Zaarei,
Volume 13, Issue 1 (3-2016)
Abstract
The micro layers micaceous iron oxide and nano-TiO 2 were incorporated into the epoxy resin by mechanical mixing and sonication process. Optical micrographs showed that the number and diameter size of nanoparticle agglomerates were decreased by sonication. The structure and composition of the nanocomposite was determined using transmission electron microscopy which showed the presence of dispersed nano-TiO 2 in the polymer matrix. The anticorrosive properties of the synthesized nano-composites coating were investigated using salt spray, electrochemical impedance spectroscopy and polarization measurement. The EIS results showed that coating resistance increased by addition of micaceous iron oxide micro layers and nano-TiO 2 particles to the epoxy coatings. It was observed that higher corrosion protection of nanocomposite coatings obtained by the addition of 3 %wt micaceous iron oxide and 4%wt nano-TiO 2 into epoxy resin.
S. Yazdani, S. Javadpour, Sh. Mehdizadeh Naderi, M. Javidi,
Volume 13, Issue 2 (6-2016)
Abstract
The inherent reactivity of the Al–Cu alloys is such that their use for structural, marine, and aerospace components and structures would not be possible without prior application of a corrosion resistance system. Historically these corrosion resistance coatings were based on the use of chemicals containing Cr (VI) compounds. Silane coatings are of increasing interest in industry due to their potential application for the replacement of current toxic hexavalent chromate based treatments. In this study, hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as 7M NH4OH) at a molar ratio of 1:25:4.31 respectively. The coatings were applied by a dip-technique to 2024-T3 Al alloy, and subsequently cured at room temperature and there after heat treated in an oven at 150°C. The anticorrosion properties of the coatings within 3.5 wt% NaCl solution were studied by Tafel polarization technique. The sol–gel coating exhibited good anticorrosion properties providing an adherent protection film on the Al 2024-T3 substrate. The surface properties were characterized by water contact angle measurement, scanning electron microscopy (SEM), and the composition was studied by Fourier transform infrared spectroscopy (FTIR).
J. Odusote, O. Ajayi,
Volume 13, Issue 3 (9-2016)
Abstract
Jatropha curcas leaves extract was tested as a green corrosion inhibitor for mild steel in aqueous hydrochloric acid solution using gravimetric and thermometric techniques. The results reveal that the inhibition efficiency vary with concentration of the leaf extract and the time of immersion. Maximum inhibition efficiency was found to be 95.92% in 2M HCl with 0.5 g/l concentration of the extract in gravimetric method, while 87.04% was obtained in thermometric method. The inhibiting effect was attributed to the presence of alkaloids, flavonoids, saponins, tannins and phenol in the extract. The adsorption processes of the Jatropha curcas leaves extract onto the mild steel is consistent with the assumptions of Langmuir isotherm model and also found to be spontaneous. From the results, a physical adsorption mechanism is proposed for the adsorption of Jatropha curcas leaves extract onto mild steel surface.
K. Susilo, A. Ahmadi, O. S. Suharyo, P. Pratisna,
Volume 14, Issue 2 (6-2017)
Abstract
Indonesian Navy (TNI AL) is the main component for Maritime Security and Defence. Because of that, TNI AL needs Indonesian Warship (KRI) to covered Maritime area. The main requirement from KRI is fulfilled by demand. To pock of fuel demand from KRI at Naval Base, it needs a new pipeline of fuel distribution network system. The pipeline network system used for maximum lifetime must be protected from corrosion. Basically, there are five methods of corrosion control such as change to a more suitable material, modification to the environment, use of protective coating, design modification to the system or component, and the application of cathodic or anodic protection. Cathodic protection for pipeline available in two kinds, namely Sacrifice Anode and Impressed Current Cathodic Protection (ICCP). This paper makes analysis from design of Impressed Current Cathodic Protection and total current requirement in the method. This paper showed both experimental from speciment test and theoritical calculation. The result showed that design of Impressed Current Cathodic Protection on fuel distribution pipeline network system requires voltage 33,759 V(DC), protection current 6,6035 A(DC) by theoritical calculation and 6,544 A(DC) from pipeline specimen test, with 0,25 mpy for corrosion rate. Transformer Rectifier design needs requirements 45 V with 10 A for current. This research result can be made as literature and standardization for Indonesian Navy in designing the Impressed Current Cathodic Protection for fuel distribution pipeline network system.
B.y.r. Surnam, B.s. Audit, A. Soopee,
Volume 14, Issue 3 (9-2017)
Abstract
In this study the use titanium and tungsten as alternatives to the noble metals in the jewellery industry was investigated. The degradation of titanium and tungsten were compared to that of gold, used as reference. Alternate immersion tests were performed in 3.5% sodium chloride and artificial perspiration. The metals’ abrasion resistance with respect to textile fabrics was determined.
In general, there is around 30% difference in pit density for titanium and tungsten as compared to that of gold. Pit depth and pit diameter showed a similar trend. From the abrasive test performed, it was observed that titanium and tungsten had insignificant changes in the surface reflectivity with time. Hence, it was deduced that titanium and tungsten products would have longer maintenance intervals than that of gold. New tools and techniques, however, would be required by jewellers to work with titanium and tungsten.
M. Shahraki, S. M. Habibi-Khorassani, M. Noroozifar, Z. Yavari, M. Darijani, M. Dehdab,
Volume 14, Issue 4 (12-2017)
Abstract
The inhibition performances of nafcillin (III), methicillin (II) and penicillin G (I) on the corrosion of copper in HCl was studied and tested by weight loss, Tafel polarization, SEM, UV-vis spectrophotometry, molecular dynamics method and quantum chemical calculations. Polarization curves indicated that the studied inhibitors act as mixed-type inhibitors. The values of inhibition efficiency and surface coverage were found to follow the order: Blank
ads, indicated that the adsorption of three inhibitors was a spontaneous process. The SEM micrographs confirmed the protection of copper in a 1 M HCl solution by penicillin G, nafcillin, and methicillin. The shape of the UV/vis spectra of inhibitors in the presence of the immersion of Cu showed a strong support to the possibility of the chemisorbed layer formation on Cu surface by nafcillin (between nafcillin and Copper) and physisorption between penicillin and methicillin with copper. DFT calculations were performed to provide further insight into the inhibition efficiencies which were determined experimentally. Molecular dynamics (MD) simulations were applied to find the most stable configuration and adsorption energies of penicillin G, nafcillin and methicillin molecules on Cu (110) surface. The interaction energy followed the order: nafcillin (III)> methicillin (II)> penicillin G (I), which confirmed that nafcillin has the strongest interaction with the metal surface. The obtained results from experimental and theoretical methods were in reasonable agreement.
M. Karimi Sahnesarayi, H. Sarpoolaky, S. Rastegari,
Volume 16, Issue 2 (6-2019)
Abstract
In this study nanosized TiO2coatings on the 316L stainless steel substrate were prepared by means of dip-coating technique in which thickness of the coating layer increased byrepeating the coating cycles in two different routes: (I) dipping and drying,respectively, were repeated one, three and five times and finally the dried coated sample was heat treated (single); (II) multiple heat treatment performed after each dipping and drying cycle, respectively.The structural, morphological and optical characterizations of coatings as well as thickness of coatings were systematically studied.The photocatalytic activity of the various TiO2 coatings was investigated based on the degradation of an aqueous solution of Methyl orange.Moreover, thecorrosion protective properties of coatings were evaluated in both dark and UV illumination conditions based on the obtained polarization curves. The results indicated 1.75 times improvement in photocatalytic reaction rate constant, a two orders of magnitude decrease in corrosion current density in dark condition and about 140 mV electrode potential reduction under UV illumination with optimum coating preparation procedure, repeating the cycle from dipping to heat treatment three times, than the sample prepared with one time coating and heat treatment since this procedure provided not only high thickness and defect-free coating but also transparent one.
V. Dave, R. Kotian, P. Madhyastha, K. Boaz, P. Rao, B.p. Charitha,
Volume 16, Issue 4 (12-2019)
Abstract
The aim of the present study is to assess the hardness, corrosion, and cytotoxicity of a commercially available cobalt-chromium (Co-Cr) alloy before and after simulated heat treatments at porcelain firing temperature. Five Co-Cr samples were fabricated using lost wax casting procedure. Heat treatments were carried out at 650°C, 750°C, 850°C, and 950°C. Vickers hardness was measured for as-cast and heat treated samples. The corrosion test was carried out separately in 0.1 N NaCl, 1% citric acid and artificial saliva at room temperature using potentiodynamic polarization technique. Gingival tissue biopsy of patients was taken and cultured to measure the cell viability by MTT colorimetric assay. Lowest hardness was observed at 650°C. 0.1 N NaCl and 1% citric acid corrosion medium showed a similar trend of corrosion rate. The least corrosion rate was found in artificial saliva. Firing temperature has an impact on the physical, chemical and biological properties of Co-Cr alloy in long-term clinical use.
Jonas Fernando Macedo, Igor Alexandre Fioravante, Roberto Zenhei Nakazato, Heloisa Andréa Acciari, Eduardo Norberto Codaro,
Volume 18, Issue 1 (3-2021)
Abstract
As we all know, corrosion of pipelines by hydrogen sulfide is the most worrying factor in the production and transport of oil and gas. In this work the corrosion behavior of API 5L X70MS and X70MO low carbon steels in hydrogen sulfide environments was investigated. Hydrogen induced cracking and sulfide stress cracking tests were carried out according to NACE TM0177 standard. After testing, blisters and cracks were observed only in X70MO steel, probably due to its lower grain refinement and banded microstructure. Internal cracks seem to be initiated in elongated MnS inclusions. Corrosion process was studied by obtaining potentiodynamic polarization curves, which were registered after open circuit potential measurements, at room temperature. Both steels showed general corrosion in NACE 177A solutions, but the corrosion rate values in H2S-saturated solution were about an order of magnitude higher than those ones in deaerated solution. Hydrogen permeation w::as char::acterized in accordance with ASTM G148 standard. In deaerated H2SO4 solution, permeation measurements were similar for both steels. In H2S-saturated solution, X70 MO exhibited higher hydrogen oxidation current values than X70 MS. H2S seems to promote the reduction of protons and increase the concentration of hydrogen atoms in the solution/steel interface, favoring the diffusion process. As X70MO has a coarse microstructure, it offers more pathways for hydrogen diffusion.
