scholarly journals Effects of the Different Solid Deposits on the Corrosion Behavior of Pure Fe in Water Vapor at 500°C

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yanbing Tang ◽  
Xinwang Shen ◽  
Zhihong Liu ◽  
Ying Li
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Mass Gain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gain Measurement ◽  
Lower Activation ◽  
Nacl Deposit ◽  
Corrosion Investigation

A comprehensive corrosion investigation of pure Fe in an environment of solid sodium salt deposit (i.e., NaCl or Na2SO4) with mixtures of H2O and O2 at 500°C was conducted by mass gain measurement, X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results showed that corrosion rates were accelerated with solid NaCl or Na2SO4 deposit due to their reaction with the formed protective scale of Fe2O3 and subsequently resulted in its breakdown. The corrosion rate of pure Fe with solid NaCl is higher than that with solid Na2SO4 because of the lower activation energy (Ea) for chemical reaction of Fe in solid NaCl+H2O+O2 (i.e., 140.5 kJ/mol) than that in solid Na2SO4+H2O+O2 (i.e., 200.9 kJ/mol). Notably, the electrochemical corrosion rate of pure Fe with solid NaCl deposit, 1.16×10−4 A/cm2, was a little lower than that with solid Na2SO4 deposit.

New Synthesis Method of the Lamellar Zinc Phosphate and its Electrochemical Corrosion Inhibitions

2011 ◽  
Vol 415-417 ◽  
pp. 1806-1809
Author(s):  
Dong Ping Wei ◽  
Sheng Fu Wu ◽  
Zeng Wei Huang ◽  
Shao Mei Ma ◽  
An Ping Liao ◽  
...  
Keyword(s):  
Zinc Phosphate ◽  
Electrochemical Impedance ◽  
Structural Characteristics ◽  
Synthesis Method ◽  
Electrochemical Corrosion ◽  
Immersion Test ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Synthesis ◽  
Lamellar Zinc

A new synthesis method namely hydrolysis precipitation was used to prepare Zn3(PO4)2•4H2O. Structural characteristics of products were investigated by X-ray Diffraction, scanning electron microscope and chemical analysis. The electrochemical corrosion inhibitions of title zinc phosphate were studied by electrochemical impedance of coating immersion test. The results show that the obtained product is a highly crystalline, micronized and lamellar Zn3(PO4)2•4H2O. Comparing with commercial zinc phosphate, the synthesized lamellar microcrystalline product has excellent anticorrosive property and dispersibility.

Structure and Corrosion Resistance of Zn-Ni and Zn-Ni-W Coatings

2010 ◽  
Vol 636-637 ◽  
pp. 1042-1046
Author(s):  
Magdalena Popczyk ◽  
Antoni Budniok
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Zinc Bath ◽  
Corrosion Resistant ◽  
X Ray ◽  
Electrochemical Corrosion Resistance ◽  
Galvanostatic Conditions

Zn-Ni and Zn-Ni-W coatings were prepared by the electrodeposition under the galvanostatic conditions (jdep. = -0.020 A cm-2) from the zinc bath containing additionally ions of nickel (Zn-Ni) and ions of nickel and tungsten (Zn-Ni-W). The Zn-Ni coating after electrodeposition was subjected to outside passivation and in the Zn-Ni-W coating the passive function performs tungsten (inside passivation). The surface morphology of the coatings was studied using a scanning electron microscope (JEOL JSM - 6480). Chemical composition of obtained coatings was determined by the X-ray fluorescence spectroscopy (XRF). Phase composition investigations were conducted by X-ray diffraction method using a Philips diffractometer. Electrochemical corrosion resistance investigations were carried out in the 3% NaCl, using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. On the basis of these investigations it was found that Zn-Ni coating is more corrosion resistant than the Zn-Ni-W coating.

Corrosion analysis of copper T2 exposed to polluted atmospheres and study on prediction model

2017 ◽  
Vol 35 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Zhiping Zhu ◽  
Xiandi Zuo ◽  
Zhaohui Ying
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Corrosion Products ◽  
Good Prediction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Early Stages ◽  
Metal Materials ◽  
The Mathematical Model

AbstractThe power supply accident caused by the corrosion of metal materials in the substation has become an important issue that affects the safe operation of the power grid. The corrosion of copper T2 was the most serious. The corrosion behaviour of copper T2 in SO2- and H2S-containing atmospheric environments was investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD), and the nonequidistant grey GM(1,1) model was established of which the precision and forecast dependability were evaluated. Results indicated that the corrosion rate of copper in the SO2 environment increased in the early stages of corrosion and then gradually decreased at the later stages. In contrast, the corrosion rate of copper in the H2S environment slowly increased in the early stages of corrosion and then sharply increased at the later stages. The corrosion products in the SO2 environment consisted of cuprite (Cu2O) and brochantite [Cu4(OH)6SO4], whereas the corrosion products in the H2S environment were Cu2O and chalcocite (Cu2S). The mathematical model has good prediction dependability and higher forecast reliability.

Effects of RE Micro-Alloying Additions on the Corrosion Behavior of an Al-Mg-Si Alloy

2017 ◽  
Vol 729 ◽  
pp. 40-45 ◽  
Author(s):  
Wei Bing Kong ◽  
Xin Xin Li ◽  
Xin Ping Hu
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Strengthening Phase ◽  
Melting Method ◽  
X Ray ◽  
Alloying Additions ◽  
Scanning Electron

AlMg5Si1-xRE (x=0%, 0.9%) alloys were prepared by resistance melting method, and the phases of alloy were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of RE (rare earth) on the corrosion resistance of AlMg5Si1 alloy immersed in seawater in different time were investigated by potential measurements and electrochemical impedance spectroscopy. The results showed that the strengthening phase β (Mg2Si) was short rod like and dispersing distributed in α (Al) in the AlMg5Si1 alloy after adding 0.9% RE. Under the conditions of seawater immersion, the corrosion rate of the AlMg5Si1RE0.9 alloy was less than that of AlMg5Si1 alloy, and the corrosion rate of AlMg5Si1RE0.9 immersed 12h in seawater was the slowest, 5.7 uA·cm-2. The improved corrosion resistance is due to the changes in microstructure and corrosion products.

scholarly journals Corrosion behaviour of copper in wet bentonite Rokle B75

2014 ◽  
Vol 58 (2) ◽  
pp. 43-47 ◽  
Author(s):  
J. Stoulil ◽  
L. Horáčková ◽  
J. Říhová-Ambrožová
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Pore Solution ◽  
Corrosion Behaviour ◽  
X Ray Diffraction ◽  
Metal Interface ◽  
Final Temperature ◽  
Compact Layer ◽  
X Ray ◽  
Bentonite Suspension

Abstract Materials for storing nuclear waste are a hot topic all over the globe right now. This study monitors corrosion behaviour of copper as one of the contemplated materials in the Czech bentonite Rokle B75. The tests were carried out in a thermostated cell deaerated with argon at temperatures of 90 and 40°C in the environment of bentonite pore solution, bentonite pore solution with an addition of sulphides and wet bentonite suspension. The scanning electron microscopy, X-ray diffraction, Raman spectroscopy, electrochemical impedance spectroscopy and resistometric methods of corrosion rate measurements were applied. The most compact layer is formed in the environment of bentonite pore solution. The addition of sulphides leads to a significant growth of thickness of the layer of corrosion products and its porosity. However, the porosity decreases towards the layer - metal interface. The layer formed after exposure to the wet bentonite suspension is reported to have the worst parameters. Nevertheless, considering the final temperature of 40°C in the repository, the corrosion rate will still be acceptable.

scholarly journals Electrodeposition Based Preparation of Zn–Ni Alloy and Zn–Ni–WC Nano-Composite Coatings for Corrosion-Resistant Applications

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 712
Author(s):  
Channagiri Mohankumar Praveen Kumar ◽  
Avinash Lakshmikanthan ◽  
Manjunath Patel Gowdru Chandrashekarappa ◽  
Danil Yurievich Pimenov ◽  
Khaled Giasin
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Substrate Surface ◽  
X Ray Diffraction ◽  
Corrosion Resistant ◽  
X Ray ◽  
Texture Coefficients ◽  
Surface Morphologies

Zinc (Zn) is one of the five most widely consumed metals in the world. Indeed, more than 50% of all the zinc produced is used in zinc-galvanizing processes to protect steel from corrosion. Zn-based coatings have the potential for use as a corrosion-resistant barrier, but their wider use is restricted due to the poor mechanical properties of Zn that are needed to protect steel and other metals from rusting. The addition of other alloying elements such as Ni (Nickle) and WC (Tungsten Carbide) to Zn coating can improve its performance. This study investigates, the corrosion performance of Zn–Ni coating and Zn–Ni–WC composite nanocoatings fabricated on mild steel substrate in an environmentally friendly bath solution. The influence of WC nanoparticles on Zn–Ni deposition was also investigated. The surface morphologies, texture coefficients via XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), and EDS (Energy-dispersive X-ray spectroscopy) were analyzed. The electrochemical test such as polarization curves (PC) and electrochemical impedance spectroscopy (EIS) resulted in a corrosion rate of 0.6948 Å/min for Zn–Ni–WC composite nanocoating, and 1.192 Å/min for Zn–Ni coating. The results showed that the Zn–Ni–WC composite nanocoating reduced the corrosion rate by 41.71% and showed an 8.56% increase in microhardness compared to the hardness of the Zn–Ni coating. These results are augmented to better wettable characteristics of zinc, which developed good interfacial metallurgical adhesion amongst the Ni and WC elements. The results of the novel Zn–Ni–WC nanocomposite coatings achieved a great improvement of mechanical property and corrosion protection to the steel substrate surface.

Effect of Zn Content on Structure, Roughness and Corrosion Behavior of Zn-Ni Alloys

2019 ◽  
Vol 17 (17) ◽  
pp. 17-22
Author(s):  
Hayette Faid
Keyword(s):  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Stripping Voltammetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ni Alloys ◽  
Sulfate Bath ◽  
Zn Content ◽  
Polarization Test ◽  
Δ Phase

AbstractIn this work, Zn-Ni alloys have been deposited on steel from sulfate bath, by electrodeposition method. The effect of Zn content on deposits properties was studied by cyclic voltammetry (CV), chronoaperometry (CA), linear stripping voltammetry (ALSV) and diffraction (XRD) and scanning electronic microscopy (SEM). The corrosion behavior in 3.5 wt. NaCl solution was examined using anodic polarization test and electrochemical impedance spectroscopy. X-ray diffraction of show that Zn-Ni alloys structure is composed of δ phase and γ phase, which increase with the decrease of Zn content in deposits. Results show that deposits obtained from bath less Zn2+ concentration exhibited better corrosion resistance.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

scholarly journals Synthesis and Na+ Ion Conductivity of Stoichiometric Na3Zr2Si2PO12 by Liquid-Phase Sintering with NaPO3 Glass

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3790
Author(s):  
Yongzheng Ji ◽  
Tsuyoshi Honma ◽  
Takayuki Komatsu
Keyword(s):  
Solid State ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Ion Conductivity ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Sintering Time ◽  
Lower Activation

Sodium super ionic conductor (NASICON)-type Na3Zr2Si2PO12 (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO3 glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na2ZrSi2O7, ZrO2, and NaPO3 glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na+ ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO3 glass has a great contribution to the Na+ diffusion at the grain boundaries.

scholarly journals Effect of Molybdenum Content on the Corrosion and Microstructure of Low-Ni, Co-Free Maraging Steels

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 852
Author(s):  
Asiful H. Seikh ◽  
Hossam Halfa ◽  
Mahmoud S. Soliman
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Alloying Element ◽  
X Ray ◽  
Maraging Steels ◽  
Eds Analysis ◽  
Electroslag Refining

Molybdenum (Mo) is an important alloying element in maraging steels. In this study, we altered the Mo concentration during the production of four cobalt-free maraging steels using an electroslag refining process. The microstructure of the four forged maraging steels was evaluated to examine phase contents by optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. Additionally, we assessed the corrosion resistance of the newly developed alloys in 3.5% NaCl solution and 1 M H2SO4 solution through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Furthermore, we performed SEM and energy-dispersive spectroscopy (EDS) analysis after corrosion to assess changes in microstructure and Raman spectroscopy to identify the presence of phases on the electrode surface. The microstructural analysis shows that the formation of retained austenite increases with increasing Mo concentrations. It is found from corrosion study that increasing Mo concentration up to 4.6% increased the corrosion resistance of the steel. However, further increase in Mo concentration reduces the corrosion resistance.

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