Pitting corrosion and crevice corrosion behaviors of titanium alloy overlapped with aluminized PVC film in neutral salt spray

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Longfei Xie ◽  
Wenlong Zhou ◽  
Shiwen Zou ◽  
Xuesong Fu
Keyword(s):  
Crevice Corrosion ◽  
Graphical Model ◽  
Electrochemical Impedance ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
Corrosion Mechanism ◽  
Neutral Salt ◽  
X Ray ◽  
Pvc Film ◽  
Corrosion Behaviors

Abstract This paper presents a research on the corrosion behavior of Ti-15-3 alloy overlapped with aluminized PVC film in salt spray. It was found that severe corrosion occurred on aluminized PVC film in the coupled regions because of crevice corrosion and/or galvanic corrosion whereas Ti-15-3 alloy in the coupled regions experienced minor corrosion. Scanning electron microscope and Energy-dispersive X-ray spectroscopy analyses demonstrated the corrosion products adhered to the surface of Ti-15-3 alloy within the crevice. To evaluate the effect of aluminized PVC film on the crevice corrosion of Ti-15-3 alloy in salt spray condition, it is necessary to compare with the corrosion resistance of Ti-15-3 overlapped with polytetrafluoroethylene (PTFE) in different neutral salt spray. Further, the tests were performed by electrochemical impedance spectroscopy and potentiodynamic polarization. Combining the graphical model, an in-depth understanding of the crevice and galvanic corrosion mechanism of Ti-15-3 alloy overlapped with aluminized PVC film has been revealed.

scholarly journals Corrosion Behaviors of the Eutectic Structure in Zn-Al-Mg Alloy Coated Steel in Chloride Containing Aqueous Environment

2020 ◽  
Vol 58 (9) ◽  
pp. 610-616
Author(s):  
Jae-Won Lee ◽  
Se-Young Oh ◽  
Bora Park ◽  
Min-Suk Oh ◽  
Sung Jin Kim
Keyword(s):  
Coating Layer ◽  
Early Stage ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
Eutectic Structure ◽  
Mg Alloy ◽  
Aqueous Environment ◽  
Corrosion Mechanism ◽  
Coated Steel ◽  
Corrosion Behaviors

To clearly understand the effect of the eutectic structure in the Zn-Al-Mg alloy coating on the corrosion behaviors in chloride containing aqueous environments, a bulk Zn-MgZn<sub>2</sub> sample was fabricated by diffusion bonding process, and a variety of experiments, such as electrochemical polarization and galvanic corrosion measurements, salt spray tests, and cyclic corrosion tests, were carried out. This study revealed that the corrosion potential values of MgZn<sub>2</sub> and Zn samples exposed to a 5 wt.% of NaCl solution were approximately -1.5 and -1 VSCE, respectively, and the MgZn<sub>2</sub> showed a higher corrosion current density than Zn at the early stage of corrosion. The continued dissolution of MgZn<sub>2</sub> phase from the eutectic structure in the coating layer provides not only sacrificial protection, but also environmental conditions for the co-formation of two types of corrosion products (simonkoleite (Zn<sub>5</sub>(OH)<sub>8</sub>Cl<sub>2</sub>·H<sub>2</sub>O) and hydrotalcite (ZnAl<sub>2</sub>(OH)<sub>6</sub>Cl<sub>2</sub>·H<sub>2</sub>O)) which have an inhibiting effect on the outer surface. The formation areas and kinetics of the two products on the coating surface were different, and they were greatly dependent upon the types of eutectic structures in the coating layer. Based on the results, a modified anti-corrosion mechanism of Zn-Al-Mg alloy coated steel sheet in chloride containing aqueous environment was proposed.

scholarly journals Graphene Oxide Decorated with Titanium Nanoparticles to Reinforce the Anti-Corrosion Performance of Epoxy Coating

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 129 ◽  
Author(s):  
Heng Yuan ◽  
Fugang Qi ◽  
Nie Zhao ◽  
Pengying Wan ◽  
Biao Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Graphene Oxide ◽  
Composite Materials ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Corrosion Mechanism ◽  
X Ray ◽  
Ti Particles

Graphene oxide–titanium (GO-Ti) composite materials were fabricated using GO as a precursor and then anchoring nano titanium (Nano-Ti) particles on GO sheets with the help of a silane coupling agent. Then, the coating samples were prepared by dispersing GO, Nano-Ti particles, and GO-Ti in an epoxy resin at a low weight fraction of 1 wt %. The GO-Ti composites were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The dispersibility and anti-corrosion mechanism of the coatings were studied by sedimentation experiments, electrochemical impedance spectroscopy (EIS), SEM, and salt spray tests. The mechanical properties of the coatings were analyzed by friction and wear tests. The results showed that the Nano-Ti particles were successfully loaded on the GO surface by chemical bonds, which made GO-Ti composites exhibit better dispersibility in the epoxy than GO. Compared with Nano-Ti particles and GO, the GO-Ti composite exhibited significant advantages in improving the corrosion resistance of epoxy coatings at the same contents, which was attributed to the excellent dispersibility, inherent corrosion resistance, and sheet structure. Among the different proportions of composite materials, the GO-Ti (2:1) material exhibited the best dispersibility and corrosion resistance. In addition, the composite material also greatly improved the wear resistance of the coating.

scholarly journals Hydrophobic Modification of Graphene Oxide and Its Effect on the Corrosion Resistance of Silicone-Modified Epoxy Resin

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 89
Author(s):  
Wei Yuan ◽  
Qian Hu ◽  
Jiao Zhang ◽  
Feng Huang ◽  
Jing Liu
Keyword(s):  
Contact Angle ◽  
Corrosion Resistance ◽  
Graphene Oxide ◽  
Physical Properties ◽  
Epoxy Resin ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
X Ray ◽  
Modified Graphene Oxide ◽  
Modified Epoxy

This study modified graphene oxide (GO) with hydrophilic octadecylamine (ODA) via covalent bonding to improve its dispersion in silicone-modified epoxy resin (SMER) coatings. The structural and physical properties of ODA-GO were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle tests. The ODA-GO composite materials were added to SMER coatings by physical mixing. FE-SEM, water absorption, and contact angle tests were used to evaluate the physical properties of the ODA-GO/SMER coatings, while salt spray, electrochemical impedance spectroscopy (EIS), and scanning Kelvin probe (SKP) methods were used to test the anticorrosive performance of ODA-GO/SMER composite coatings on Q235 steel substrates. It was found that ODA was successfully grafted onto the surfaces of GO. The resulting ODA-GO material exhibited good hydrophobicity and dispersion in SMER coatings. The anticorrosive properties of the ODA-GO/SMER coatings were significantly improved due to the increased interfacial adhesion between the nanosheets and SMER, lengthening of the corrosive solution diffusion path, and increased cathodic peeling resistance. The 1 wt.% ODA-GO/SMER coating provided the best corrosion resistance than SMER coatings with other amounts of ODA-GO (including no addition). After immersion in 3.5 wt.% NaCl solution for 28 days, the low-frequency end impedance value of the 1 wt.% ODA-GO/SMER coating remained high, at 6.2 × 108 Ω·cm2.

scholarly journals Design and Multidimensional Screening of Flash-PEO Coatings for Mg in Comparison to Commercial Chromium(VI) Conversion Coating

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 337
Author(s):  
Ewa Wierzbicka ◽  
Marta Mohedano ◽  
Endzhe Matykina ◽  
Raul Arrabal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Chromium Vi ◽  
Alkaline Electrolytes ◽  
Az31b Alloy ◽  
Plasma Electrolytic

REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations demand for an expedient discovery of a Cr(VI)-free alternative corrosion protection for light alloys even though the green alternatives might never be as cheap as current harmful technologies. In the present work, flash- plasma electrolytic oxidation coatings (FPEO) with the process duration < 90 s are developed on AZ31B alloy in varied mixtures of silicate-, phosphate-, aluminate-, and fluoride-based alkaline electrolytes implementing current density and voltage limits. The overall evaluation of the coatings’ anticorrosion performance (electrochemical impedance spectroscopy (EIS), neutral salt spray test (NSST), paintability) shows that from nine optimized FPEO recipes, two (based on phosphate, fluoride, and aluminate or silicate mixtures) are found to be an adequate substitute for commercially used Cr(VI)-based conversion coating (CCC). The FPEO coatings with the best corrosion resistance consume a very low amount of energy (~1 kW h m−2 µm−1). It is also found that the lower the energy consumption of the FPEO process, the better the corrosion resistance of the resultant coating. The superb corrosion protection and a solid environmentally friendly outlook of PEO-based corrosion protection technology may facilitate the economic justification for industrial end-users of the current-consuming process as a replacement of the electroless CCC process.

scholarly journals Application of Commercial Surface Pretreatments on the Formation of Cerium Conversion Coating (CeCC) over High-Strength Aluminum Alloys 2024-T3 and 7075-T6

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 930
Author(s):  
Juan Jesús Alba-Galvín ◽  
Leandro González-Rovira ◽  
Francisco Javier Botana ◽  
Maria Lekka ◽  
Francesco Andreatta ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Salt Spray ◽  
Aluminum Matrix ◽  
Optical Emission ◽  
High Strength ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Corrosion Properties ◽  
Surface Pretreatment

The selection of appropriate surface pretreatments is one of the pending issues for the industrial application of cerium-based chemical conversion coatings (CeCC) as an alternative for toxic chromate conversion coating (CrCC). A two-step surface pretreatment based on commercial products has been successfully used here to obtain CeCC on AA2024-T3 and AA7075-T6. Specimens processed for 1 to 15 min in solutions containing CeCl3 and H2O2 have been studied by scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX), glow discharge optical emission spectroscopy (GDOES), potentiodynamic linear polarization (LP), electrochemical impedance spectroscopy (EIS), and neutral salt spray (NSS) tests. SEM-EDX showed that CeCC was firstly observed as deposits, followed by a general coverage of the surface with the formation of cracks where the coating was getting thicker. GDOES confirmed an increase of the CeCC thickness as the deposition proceed, the formation of CeCC over 7075 being faster than over 2024. There was a Ce-rich layer in both alloys and an aluminum oxide/hydroxide layer on 7075 between the upper Ce-rich layer and the aluminum matrix. According to LP and EIS, CeCC in all samples offered cathodic protection and comparable degradation in chloride-containing media. Finally, the NSS test corroborated the anti-corrosion properties of the CeCC obtained after the commercial pretreatments employed.

scholarly journals Enhancement of the cerium oxide primer layers deposited on AA2024-T3 aircraft alloy by preliminary Enhancement of the cerium oxide primer layers deposited on AA2024-T3 aircraft alloy by preliminary anodization

2018 ◽  
Author(s):  
Stephan V. Kozhukharov ◽  
Christian Girginov
Keyword(s):  
Cerium Oxide ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Salt Spray ◽  
Neutral Salt ◽  
Anodized Aluminum ◽  
Cross Sectional ◽  
Anodized Aluminum Oxide ◽  
Linear Voltammetry ◽  
And Performance

<p class="PaperAbstract"><span lang="EN-US">The possibility for combination between Anodized Aluminum Oxide (AAO) and Cerium Oxide Primer Layer (CeOPL) for elaboration of efficient protective coatings for AA2024-T3 aircraft alloy is proposed in the present research. The combined AAO/CeOPL coating characterizations include Electrochemical Impedance Spectroscopy (EIS) combined with Linear Voltammetry (LVA), for extended times (until 2520 hours) to a model corrosive medium (3.5% NaCl). Topographical and cross-sectional (SEM and EDX) observations were performed in order to determine the AAO/CeOPL film thickness and composition. The AAO/CeOPL layer durability tests were confirmed by standard Neutral Salt Spray (NSS). The data analysis from all the used measurement methods has undoubtedly shown that the presence of AAO film significantly improves the cerium oxide primer layer (CeOPL) protective properties and performance. </span></p>

Corrosion resistance of composite coating used for fastener protection

2019 ◽  
Vol 66 (5) ◽  
pp. 595-602
Author(s):  
Zhifeng Lin ◽  
Likun Xu ◽  
Xiangbo Li ◽  
Li Wang ◽  
Weimin Guo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
Composite Coating ◽  
Marine Environment ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Diffusion Method ◽  
Economic Losses ◽  
Neutral Salt ◽  
Content Type

Purpose The purpose of this paper is to examine the performance of a fastener composite coating system, sherardized (SD) coating/zinc-aluminum (ZA) coating whether it has good performance in marine environment. Design/methodology/approach In this paper, SD coating was fabricated on fastener surface by solid-diffusion method. ZA coating was fabricated by thermal sintering method. Corrosion behaviours of the composite coating were investigated with potentiodynamic polarization curves, open circuit potential and electrochemical impedance spectroscopy methods. Findings Neutral salt spray (NSS) and deep sea exposure tests revealed that the composite coating had excellent corrosion resistance. Polarization curve tests showed that corrosion current density of the sample with composite coating was significantly decreased, indicating an effective corrosion protection of the composite coating. OCP measurement of the sample in NaCl solution demonstrated that the composite coating had the best cathodic protection effect. The good corrosion resistance of the composite coating was obtained by the synergy of SD and ZA coating. Practical implications SD/ZA coating can be used in marine environment to prolong the life of carbon steel fastener. Social implications SD/ZA composite coating can reduce the risk and accident caused by failed fastener, avoid huge economic losses. Originality/value A new kind of composite coating was explored to protect the carbon steel fastener in marine environment. And the composite coating has the long-term anti-corrosion performance both in simulated and marine environment test.

scholarly journals Effect of Rare Earth Oxides on Microstructure and Corrosion Behavior of Laser-Cladding Coating on 316L Stainless Steel

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 636 ◽  
Author(s):  
Xu ◽  
Wang ◽  
Chen ◽  
Qiao ◽  
Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Rare Earth ◽  
Corrosion Behavior ◽  
Laser Cladding ◽  
316L Stainless Steel ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Rare Earth Oxides ◽  
X Ray Diffraction ◽  
X Ray

The effect of rare earth oxides on the microstructure and corrosion behavior of laser-cladding coating on 316L stainless steel was investigated using hardness measurements, a polarization curve, electrochemical impedance spectroscopy (EIS), a salt spray test, X-ray diffraction, optical microscopy, and scanning electron microscopy (SEM). The results showed that the modification of rare earth oxides on the laser-cladding layer caused minor changes to its composition but refined the grains, leading to an increase in hardness. Electrochemical and salt spray studies indicated that the corrosion resistance of the 316L stainless steel could be improved by laser cladding, especially when rare earth oxides (i.e., CeO2 and La2O3) were added as a modifier.

scholarly journals Role of Vanadium Additions on the Corrosion Mitigation of Ti-6Al-xV Alloy in Simulated Body Fluid

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 903 ◽  
Author(s):  
El-Sayed M. Sherif ◽  
Sameh A. Ragab ◽  
Hany S. Abdo
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Immersion Time ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cyclic Potentiodynamic Polarization ◽  
Elemental Analyses ◽  
Corrosion Behaviors

The manufacturing of different Ti-6Al-xV (x = 2, 4, 6, and 8 wt.%) alloys using a mechanical alloying technique was reported. The corrosion behaviors of these newly fabricated alloys after 1, 24, and 48 h exposure to a simulated body fluid (SBF) were assessed using cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and chronoamperometric measurements. Surface morphology and elemental analyses after corrosion for 48 h in SBF were reported using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) examinations. An X-ray diffraction investigation characterized the phase analyses. All results indicated that the increase of V content significantly decreases both uniform and pitting corrosion. This effect also increases with prolonging the immersion time to 48 h before measurement.

scholarly journals Effect of Temperature on the Corrosion Behavior of Biodegradable AZ31B Magnesium Alloy in Ringer’s Physiological Solution

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 591 ◽  
Author(s):  
Sebastian Feliu ◽  
Lucien Veleva ◽  
Federico García-Galvan
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Physiological Solution ◽  
Corrosion Layer ◽  
Effect Of Temperature ◽  
X Ray ◽  
Ringer’S Solution ◽  
Corrosion Behaviors ◽  
Az31b Alloy ◽  
Increasing Temperature

In this work, the corrosion behaviors of the AZ31B alloy in Ringer’s solution at 20 °C and 37 °C were compared over four days to better understand the influence of temperature and immersion time on corrosion rate. The corrosion products on the surfaces of the AZ31B alloys were examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) provided information about the protective properties of the corrosion layers. A significant acceleration in corrosion rate with increasing temperature was measured using mass loss and evolved hydrogen methods. This temperature effect was directly related to the changes in chemical composition and thickness of the Al-rich corrosion layer formed on the surface of the AZ31B alloy. At 20 °C, the presence of a thick (micrometer scale) Al-rich corrosion layer on the surface reduced the corrosion rate in Ringer’s solution over time. At 37 °C, the incorporation of additional Mg and Al compounds containing Cl into the Al-rich corrosion layer was observed in the early stages of exposure to Ringer’s solution. At 37 °C, a significant decrease in the thickness of this corrosion layer was noted after four days.

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