scholarly journals Improving Corrosion Resistance of Magnesium Alloy in Cl- Containing Simulated Concrete Pore Solution by Ultrasound-Assisted Chemical Deposition

Scanning ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ye Wang ◽  
Guosong Wu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Pore Solution ◽  
Chemical Deposition ◽  
Deposition Process ◽  
Cross Sectional ◽  
X Ray ◽  
Electrochemical Tests ◽  
Reaction Solution ◽  
Building Engineering

Coatings are playing an important role in corrosion mitigation of magnesium alloys, and in this study, a facile and eco-friendly chemical deposition process is proposed to improve the corrosion resistance of magnesium-neodymium alloys. The mixture of 1.5 mol/L KH2PO4 solution and 1.2 mol/L CaCl2 solution is used for reaction solution, and ultrasound is introduced into the process for assisting the chemical deposition. After 40 minutes of the surface treatment, the surface and cross-sectional morphologies are observed by scanning electron microscope (SEM), which reveals that a layer of dense coating is formed on Mg alloy. Energy-dispersive X-ray spectroscopy (EDS) and X-ray Diffraction (XRD) are further combined to analyze the coating, and it is thereby confirmed that this coating mainly consists of CaHPO4·2H2O. Electrochemical tests and soaking experiments are conducted to evaluate the corrosion resistance of the treated samples in simulated concrete pore solutions. Both the untreated and treated samples have a good corrosion resistance in the Cl- free simulated concrete pore solution, but their corrosion behavior is influenced by the introduction of Cl- in this study. Fortunately, the coating can protect the substrate effectively in the Cl- containing simulated concrete pore solution. In summary, it provides a possible way for magnesium alloys to improve their corrosion resistance when they are used in building engineering.

scholarly journals Improved Corrosion Resistance of Magnesium Alloy in Simulated Concrete Pore Solution by Hydrothermal Treatment

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-7 ◽  
Author(s):  
Ye Wang ◽  
Guosong Wu ◽  
Jiapeng Sun
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Hydrothermal Treatment ◽  
Building Materials ◽  
Pore Solution ◽  
Chloride Ions ◽  
Al Alloy ◽  
Natural Immunity ◽  
X Ray ◽  
Building Engineering

Magnesium alloys are considered for building materials in this study due to their natural immunity to corrosion in alkaline concrete pore solution. But, chloride ions attack often hinders the application of most metals. Therefore, it is necessary to conduct a preliminary corrosion evaluation and attempt to find an effective way to resist the attack of chloride ions in concrete pore solution. In our study, hydrothermal treatment is carried out to modify Mg-9.3 wt. % Al alloy. After the treatment in NaOH solution for 10 h, scanning electron microscopy (SEM) reveals that a layer of dense coating with a thickness of about 5 μm is formed on Mg alloy. Energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD) are combined to analyze the coating, and it is thereby confirmed that the coating is mainly composed of Mg(OH)2. As expected, both immersion test and electrochemical corrosion test show that the coated magnesium alloy has a better corrosion resistance than the uncoated one in simulated concrete pore solution with and without chloride ions. In summary, it indicates that hydrothermal treatment is a feasible method to improve the corrosion resistance of Mg alloys used for building engineering from the perspective of corrosion science.

scholarly journals The Corrosion Resistance of Aluminum–Bronze Coatings as a Function of Gas Pressure Used in the Thermal Spraying Process

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 507 ◽  
Author(s):  
Alfredo Morales ◽  
Oscar Piamba ◽  
Jhon Olaya
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Thermal Spraying ◽  
Deposition Process ◽  
Gas Pressure ◽  
Aluminum Bronze ◽  
Porosity Level ◽  
X Ray ◽  
Aluminum Coatings ◽  
Transmission Electron

We report the results of the influence of acetylene and oxygen gas pressure on the corrosion resistance of bronze–aluminum coatings deposited on a naval brass substrate by means of the thermal (flame) deposition process. The coatings were characterized by means of scanning electronic microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and transmission electron microscopy (TEM). The corrosion tests were carried out via Tafel and electrochemical impedance spectroscopy (EIS). In addition, some samples were selected in order to investigate heat treatment and its effects on corrosion resistance. The results indicate that changes in the pressure and flow of the gas affects the composition, morphology, and physical properties of the coatings, and these effects have consequences for the behavior of the coatings when they are immersed in corrosion environments. The collision speed of the particles was identified as the most significant factor that influences the properties and the performance of the coating. The gas pressure modified the oxides and the porosity level, which improved the corrosion resistance.

MICROSTRUCTURE AND ELECTROCHEMICAL PROPERTIES OF Ni–B/GO ULTRASONIC-ASSISTED COMPOSITE COATINGS

2019 ◽  
Vol 26 (10) ◽  
pp. 1950080
Author(s):  
JIBO JIANG ◽  
HAOTIAN CHEN ◽  
LIYING ZHU ◽  
YAOXIN SUN ◽  
WEI QIAN ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Ultrasonic Field ◽  
Protective Material ◽  
X Ray ◽  
Electrochemical Tests ◽  
Ultrasonic Assisted ◽  
Corrosive Environments

Graphene oxide (GO) sheet and ultrasonic field (UF) were successfully employed to produce Ni–B/GO and UF–Ni–B/GO composite coatings on Q235 mild steel by electroless plating. The composite coatings’ structure and surface morphology were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Results showed that GO was successfully co-deposited in the Ni–B alloy. Moreover, UF–Ni–B/GO composite coatings have smoother surface and thicker cross-section than others. The microhardness and corrosion resistance of the sample coatings were determined using Vickers hardness tests, Tafel electrochemical tests and electrochemical impedance measurements (EIS) in 3.5[Formula: see text]wt.% NaCl solution to receive the effect of GO and ultrasonic. The findings indicated that UF–Ni–B/GO exhibited optimum hardness (856[Formula: see text]HV) and enhanced corrosion resistance (6.38 [Formula: see text][Formula: see text] over the Ni–B and Ni–B/GO coatings. Due to these interesting properties of the coating, it could be used as a protective material in the automotive and aerospace industries for parts of machines that were manipulated in high temperature and corrosive environments.

Study on Properties of Zn-Al-Mg-RE Coatings by Arc Spraying

2013 ◽  
Vol 804 ◽  
pp. 79-84
Author(s):  
Fei Lu ◽  
Zhao Qian Xie ◽  
Yu Feng Lu ◽  
Miao Lou ◽  
Meng Zhou ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Arc Spraying ◽  
Long Term Effects ◽  
Electrochemical Protection ◽  
X Ray ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
Corrosion Reaction ◽  
High Velocity Arc Spraying

In order to improve the organization, reduce the porosity, compact the structure and enhance the corrosion resistance of the coating, Zn-Al-Mg-RE coating system was prepared by high velocity arc spraying. The surface appears, phase composition and electrochemical properties of the coating were characterized by scanning electron microscope, X-ray radiation diffaction and electrochemical workstation. The results indicated that the coatings were compact. The coatings were mainly zinc and aluminum phase. In corrosion of immersion, the reaction resistance and coating resistance of coatings quickly become bigger, the surface of coatings become more compact, and the corrosion reaction is more difficult. Electrochemical tests showed that the coating had excellent corrosion resistance. The electrochemical protection and self-sealing effect of coatings can have long-term effects on anticorrosion.

Corrosion Behavior of Surfaced AM50 Magnesium Alloys under Stress Conditions

2010 ◽  
Vol 95 ◽  
pp. 79-83
Author(s):  
Amir Eliezer
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Spinel Phase ◽  
Ceramic Coatings ◽  
Open Circuit ◽  
Stress Conditions ◽  
X Ray Diffraction ◽  
X Ray

Micro-arc oxidization of AM50 magnesium alloys was studied. The influence of micro-arc oxidization process was investigated; phase structure were analyzed using X-ray diffraction (XRD). Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of ceramic coatings formed on magnesium alloys under stress conditions. XRD analyses indicate that the ceramic coatings fabricated on the surface of magnesium alloys by micro-arc oxidization are composed of spinel phase MgAl2O4 The corrosion resistance of ceramic coatings is improved compared with magnesium alloy substrate.

Hexagonal Boron Nitride Nanowalls Synthesized by Unbalanced RF Magnetron Sputtering

2011 ◽  
Vol 1307 ◽  
Author(s):  
Boumédiène BenMoussa ◽  
Jan D’Haen ◽  
Christian Borschel ◽  
Marc Saitner ◽  
Ali Soltani ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Film Thickness ◽  
Hexagonal Boron Nitride ◽  
Rf Magnetron Sputtering ◽  
Deposition Process ◽  
Dense Layer ◽  
Cross Sectional ◽  
X Ray ◽  
Optical And Electronic Properties ◽  
Film Interface

ABSTRACTA recurrent problem in the synthesis of hexagonal boron nitride (h-BN) is contamination with oxygen and carbon, leading to possible detrimental effects on optical and electronic properties. Here it is shown that the addition of H2 to the N2/Ar mixture used during the deposition process, clearly suppresses the incorporation of these elements, reducing their combined level below 5 %. The surface morphology, assessed with scanning electron microscopy (SEM), revealed the presence of h-BN nanowalls, i.e. vertically positioned 2D structures consisting out of several h-BN sheets. While Fourier transform infrared (FTIR) spectroscopy revealed the sp2 nature of the bonds, confirming the hexagonal nature of the nanowalls, the quasi-perfect stoichiometry of the material was evidenced by combining energy dispersive X-ray analysis (EDX) and Rutherford backscattering spectroscopy (RBS). The dimensions and density of these walls are clearly film thickness dependent and cross-sectional TEM images confirmed the increasing level of porosity with film thickness. A dense layer of material is present at the substrate-film interface, which gradually evolves into the 2D nanowall structures.

scholarly journals Tunable Microstructure and Morphology of the Self-Assembly Hydroxyapatite Coatings on ZK60 Magnesium Alloy Substrates Using Hydrothermal Methods

Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 8
Author(s):  
Taolei Wang ◽  
Chao Lin ◽  
Dan Batalu ◽  
Jingzhou Hu ◽  
Wei Lu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Self Assembly ◽  
Ph Value ◽  
Precursor Solution ◽  
Electrochemical Tests ◽  
Ha Coating ◽  
Hydroxyapatite Coatings ◽  
And Performance ◽  
Biodegradable Magnesium

Hydroxyapatite coatings have been widely used to improve the corrosion resistance of biodegradable magnesium alloys. In this paper, in order to manufacture the ideal hydroxyapatite (HA) coating on the ZK60 magnesium substrate by hydrothermal method, formation mechanism of enhanced hydroxyapatite (HA) coatings, influence of pH values of the precursor solution on the HA morphology, corrosion resistance and cytotoxicity of HA coatings have been investigated. Results show that the growth pattern of the HA is influenced by the local pH value. HA has a preferential c-axis and higher crystallinity in the alkaline environment developing a nanorod-like structure, while in acid and neutral environments it has a preferential growth along the a(b)-plane with a lower crystallinity, developing a nanosheet-like structure. The different morphology and microstructure lead to different degradation behavior and performance of HA coatings. Immersion and electrochemical tests show that the neutral environment promote formation of HA coatings with high corrosion resistance. The cell culture experiments confirm that the enhanced corrosion resistance assure the biocompatibility of the substrate-coating system. In general, the HA coating prepared in neutral environment shows great potential in surface modification of magnesium alloys.

Corrosion of the Materials in Sulfuric Acid

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Hong Pyo Kim ◽  
Dong-Jin Kim ◽  
Hyuk Chul Kwon ◽  
Ji Yeon Park ◽  
Yong Wan Kim
Keyword(s):  
Corrosion Resistance ◽  
Sulfuric Acid ◽  
Hydrogen Production ◽  
Cross Sectional ◽  
Corrosion Morphology ◽  
X Ray ◽  
Nuclear Heat ◽  
Corrosion Behaviors ◽  
Materials Used ◽  
Surface Morphologies

A program for a hydrogen production by using a high temperature nuclear heat has been launched in Korea since 2004. Iodine sulfur (IS) process is one of the promising processes for a hydrogen production because it does not generate carbon dioxide and a massive hydrogen production may be possible. However, the highly corrosive environment of the process is a barrier to its application in the industry. Therefore, corrosion behaviors of various materials were evaluated in sulfuric acid to select appropriate materials compatible with the IS process. The materials used in this work were Ni based alloys, Fe–Si alloys, Ta, Au, Pt, Zr, SiC, and so on. The test environments were boiling 50 wt % sulfuric acid without/with HI as an impurity and 98 wt % sulfuric acid. The surface morphologies and cross-sectional areas of the corroded materials were examined by using the scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). From the results of the weight loss and potentiodynamic experiments, it was found that a Si enriched oxide is attributable to a corrosion resistance for materials including Si in boiling 98 wt % sulfuric acid. Moreover, the passive Si enriched film thickness increased with the immersion time leading to an enhancement of the corrosion resistance. Corrosion behaviors of the material tested are discussed in terms of the chemical composition of the materials, the corrosion morphology, and the surface layer’s composition.

Preparation and properties of natural gallic acid based rust conversion emulsion

2016 ◽  
Vol 45 (3) ◽  
pp. 191-198 ◽  
Author(s):  
Yuanfeng Jia ◽  
Nana Ren ◽  
Huadong Yue ◽  
Jianru Deng ◽  
Yali Liu
Keyword(s):  
Raman Spectroscopy ◽  
Corrosion Resistance ◽  
Gallic Acid ◽  
Photoelectron Spectroscopy ◽  
High Efficiency ◽  
Hydroxyl Groups ◽  
Content Type ◽  
X Ray ◽  
Electrochemical Tests ◽  
Emulsion Polymerisation

Purpose The paper developed a novel gallic acid-based rust conversion emulsion (RCE) that is applied in the treatment of rusted steels. The purpose of this paper is to investigate the methods for the synthesis of RCE and study the mechanism of rust conversion. Design/methodology/approach Conversion emulsion was prepared using styrene, acrylate and self-developed gallic acid (GA)-based rust converter (GRC) via seed emulsion polymerisation. The polymerisable GRC was synthesised by the ring-opening reaction of glycidyl methacrylate with natural GA. The effects of the GRC dosage and its feeding modes on the RCE synthesis were analysed. The corrosion resistance, surface morphology, composition and mechanism of rust conversion coatings were studied using electrochemical tests, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. Findings The results showed that conversion coating on rusted steels treated with RCE, with various dosages of GRC (weight per cent), synthesised using seed emulsion polymerisation, exhibited the best adhesion and corrosion resistance. Raman spectroscopy revealed that RCE converted the original multiphase rust into stable crystalline phases of α-Fe2O3 and Fe3O4. According to XPS and energy dispersive X-ray analysis, the phenolic hydroxyl groups of RCE were proposed to chelate with Fe ions to form macromolecular ferrum compounds. Research limitations/implications The pre-rusted steels demonstrated a better corrosion resistance than rust-free steels after treatment with RCE. Practical implications The paper developed a novel GA-based RCE with high efficiency and environment-friendly method. Originality/value This work is expected to replace the conventional rust conversion paints and cause a significant impact on extending the service life of rusted steels.

Corrosion products on biomedical magnesium alloy soaked in simulated body fluids

2009 ◽  
Vol 24 (8) ◽  
pp. 2711-2719 ◽  
Author(s):  
Yunchang Xin ◽  
Kaifu Huo ◽  
Tao Hu ◽  
Guoyi Tang ◽  
Paul K Chu
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Corrosion Product ◽  
Calcium Phosphates ◽  
Product Layer ◽  
Cross Sectional ◽  
X Ray ◽  
Oxide Hydroxide ◽  
Corrosion Product Layer ◽  
Simulated Body Fluids

Magnesium alloys are potential materials in biodegradable hard tissue implants. Their degradation products in the physiological environment not only affect the degradation process but also influence the biological response of bone tissues. In the work reported here, the composition and structure of the corrosion product layer on AZ91 magnesium alloy soaked in a simulated physiological environment, namely simulated body fluids (SBFs), are systematically investigated using secondary electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and in situ monitoring of the corrosion morphology. Our results show that the corrosion product layer comprises mainly amorphous magnesium (calcium) phosphates, magnesium (calcium) carbonates, magnesium oxide/hydroxide, and aluminum oxide/hydroxide. The magnesium phosphates preferentially precipitate at obvious corrosion sites and are present uniformly in the corrosion product layer, whereas calcium phosphates nucleate at passive sites first and tend to accumulate at isolated and localized sites. According to the cross sectional views, the corrosion product layer possesses a uniform structure with thick regions several tens of micrometers as well as thin areas of several micrometers in some areas. Localized corrosion is the main reason for the nonuniform structure as indicated by the pan and cross-sectional views. The results provide valuable information on the cytotoxicity of magnesium alloys and a better understanding on the degradation mechanism of magnesium alloys in a physiological environment.

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