Corrosion behaviour of hot-dip Zn-Al-Mg coatings with different Al content

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Prabhat Kumar Rai ◽  
Dinesh Rout ◽  
D. Satish Kumar ◽  
Sanjay Sharma ◽  
G. Balachandran
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behaviour ◽  
Steel Substrate ◽  
Salt Spray ◽  
Protective Film ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Content Type ◽  
Al Content ◽  
Process Simulator

Purpose The purpose of the present study is to simulate the industrial hot-dip process of Zn-2.5Wt.%Mg-3 Wt.%Al and Zn-2.5 Wt.%Mg-9 Wt.%Al-0.15 Wt.%Si coatings and to study the effect of low and high Al variation on their microstructure, microhardness, adhesion and corrosion behaviour. Design/methodology/approach The hot-dip Zn-2.5 Mg-xAl coating simulation on steel substrate was carried out using a hot-dip process simulator. The microstructure of the coatings was characterized using a scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. The corrosion behaviour of the coatings was studied using a salt spray test in 5% NaCl solution as well as dynamic polarization in 3.5% NaCl solution. Findings Microhardness of the developed Zn-2.5 Mg-xAl coatings has been found to be approximately two times higher than that of the conventional galvanized coating. Zn-2.5 Mg-3Al coating has exhibited two times higher corrosion resistance as compared to that of Zn-2.5 Mg-9Al-0.15Si coating because of formation of more homogeneous and defect-free microstructure of the former. The MgZn2 phase has undergone preferential dissolution and provided Mg2+ ions to form a protective film. Originality/value The relative corrosion resistance of the two Zn–Al–Mg coatings with different Al content has been studied. The defect formed because of higher Al addition in the coating has been detected, and its effect on corrosion behaviour has been analysed.

Effect of rare earth lanthanum-cerium doping on corrosion behavior of zinc-aluminum-magnesium hot-dip galvanizing coatings used for transmission towers

2018 ◽  
Vol 65 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Yu Han ◽  
Yanqiu Xia ◽  
Xin Chen ◽  
Liang Sun ◽  
Dongyu Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Rare Earths ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Salt Spray ◽  
X Ray Diffraction ◽  
Copper Strip ◽  
Cross Sectional ◽  
Content Type ◽  
Transmission Towers

Purpose The purpose of this study is to improve the corrosion resistance of the transmission towers by Zinc-aluminum-magnesium (Zn-Al-Mg) coatings doped with rare earths lanthanum (La) and cerium (Ce) (denoted as Zn-Al-Mg-Re) in Q345 steel. Design/methodology/approach The phase structure of Zn-Al-Mg-Re composite coatings has been determined by X-ray diffraction, whereas their surface morphology and cross-sectional microstructure as well as cross-sectional elemental composition have been analyzed by scanning electron microscopy and energy-dispersive spectrometry. Moreover, the corrosion resistance of Zn-Al-Mg-Re composite coatings has been evaluated by acetic acid accelerated salt spray test of copper strip. Findings Experimental results show that doping with La and Ce favors to tune the composition (along with the generation of new phase, such as LaAl3 or Al11Ce3) and refine the microstructure of Zn-Al-Mg galvanizing coatings, thereby significantly improving the corrosion resistance of the coatings. Particularly, Zn-Al-Mg-Re with 0.15% (mass fraction) La exhibits the best corrosion resistance among the tested galvanizing coatings. Originality/Value Zinc-aluminum-magnesium (Zn-Al-Mg) coatings doped with rare earths lanthanum (La) and cerium (Ce) (denoted as Zn-Al-Mg-Re) have been prepared on Q345 steel substrate by hot-dip galvanizing so as to improve the corrosion resistance of the transmission towers, and to understand the corrosion inhibition of the Zn-Al-Mg-Re coating.

Influence of plasma spraying parameters on microstructure and corrosion resistance of Cr3C2-25NiCr cermet carbide coating

2019 ◽  
Vol 66 (3) ◽  
pp. 336-342 ◽  
Author(s):  
Tuan Nguyen Van ◽  
Tuan Anh Nguyen ◽  
Quy Le Thu ◽  
Ha Pham Thi
Keyword(s):  
Corrosion Resistance ◽  
Potentiodynamic Polarization ◽  
Corrosion Behaviour ◽  
Steel Substrate ◽  
Salt Spray ◽  
Compositional Analysis ◽  
Atmospheric Plasma ◽  
Content Type ◽  
Spraying Parameters ◽  
Hardness Scale

Purpose In this work, Cr3C2-25NiCr coatings were deposited on 410 stainless steel substrate by using the atmospheric plasma spray technique, at varying spaying parameters. The porosity and microhardness, adhesion strength and corrosion behaviour of coatings were examined in relation to these spraying parameters. Design/methodology/approach The microstructure of prepared coatings was examined by using scanning electron microscopy. The coating compositional analysis was performed by using X-ray diffraction (XRD) technique. The corrosion resistance of coated steel was investigated by potentiodynamic polarization. Results indicate that optimal factors for minimalizing the porosity were as follows: 10 g/min feed rate, 600 A plasma current and 100 mm spraying distance. The spraying factors influencing corrosion resistance of coating were also evaluated. Findings Under this optimal condition, the porosity of coating reached its minimal value of 3.1 per cent. The microhardness and adhesion of coatings also reached their maximum values of 64.8 Rockwell Hardness scale C and 60 MPa, respectively. XRD results indicated the transformation of Cr3C2 originating from Cr3C2-25NiCr source powder into Cr7C3 and Cr23C6 crystalline phases, due to the high temperature during spraying process. The undetectable Cr3C2 peaks indicating that this phase was remained in coating at very low concentrations. The potentiodynamic polarization and salt spray tests confirmed the highest corrosion resistance for the coating prepared by optimal spraying parameters. Originality/value The application of Cr3C2-NiCr cermet carbit coating for protection of steel from corrosion-erosion is very promising.

Appraisal on corrosion performances of CrNi, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings on H13 hot work mold

2020 ◽  
Vol 67 (2) ◽  
pp. 150-157
Author(s):  
Kong Dejun ◽  
Li Jiahong
Keyword(s):  
Corrosion Resistance ◽  
Salt Spray ◽  
Test Chamber ◽  
Electrochemical Corrosion ◽  
Optical Microscope ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
H13 Steel ◽  
Content Type ◽  
Electrochemical Corrosion Resistance

Purpose The purpose of this paper is to evaluate the salt spray corrosion (SSC) and electrochemical corrosion performances of CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings on H13 steel, which improved the corrosion resistance of H13 hot work mold. Design/methodology/approach CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings were fabricated on H13 hot work mold steel using a laser cladding and cathodic arc ion plating. The SSC and electrochemical performances of obtained coatings were investigated using a corrosion test chamber and electrochemical workstation, respectively. The corrosion morphologies, microstructure and phases were analyzed using an electron scanning microscope, optical microscope and X-ray diffraction, respectively, and the mechanisms of corrosion resistance were also discussed. Findings The CrNi coating is penetrated by corrosion media, producing the oxide of Fe3O4 on the coating surface; and the TiAlN coating is corroded to enter into the CrNi coating, forming the oxides of TiO and NiO, the mechanism is pitting corrosion, whereas the CrNi–Al2O3–TiO2 coating is not penetrated, with no oxides, showing the highest SSC resistance among the three kinds of coatings. The corrosion potential of CrNi coating, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings was –0.444, –0.481 and –0.334 V, respectively, and the corresponding polarization resistances were 3,074, 2,425 and 86,648 cm2, respectively. The electrochemical corrosion resistance of CrNi–Al2O3–TiO2 coating is the highest, which is enhanced by the additions of Al2O3 and TiO2. Originality/value The CrNi, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings on H13 hot work mold were firstly evaluated by the SSC and electrochemical performances.

Microstructure and corrosion behaviour of precipitation hardened and thermo-mechanical treated high strength Al-12Zn-3Mg-2.5Cu alloy

2018 ◽  
Vol 65 (1) ◽  
pp. 79-86 ◽  
Author(s):  
V.V. Ravikumar ◽  
S. Kumaran
Keyword(s):  
Corrosion Resistance ◽  
Precipitation Hardening ◽  
Corrosion Behaviour ◽  
Cast Alloy ◽  
High Strength ◽  
Structural Features ◽  
Boundary Region ◽  
Nacl Solution ◽  
Content Type ◽  
Fine Grained Structure

Purpose The purpose of this paper is to study the corrosion behaviour of Al-12Zn-3Mg-2.5Cu alloy by cast, precipitation hardening and non-isothermal step rolling cum cold/cryo rolling (−80 and −196°C) in 3.5 per cent NaCl solution. Design/methodology/approach Aluminium alloy with high alloying concentration (Zn: 12 per cent, Mg: 3 per cent, Cu: 2.5 per cent) was prepared by squeeze casting method with controlled process parameters. The cast alloy was solution treated at 450°C for 24 h and aged at 120°C with varying time intervals. Initially, the alloy also underwent non-isothermal step rolling from 6 mm to 3 mm at 400-100°C at the step of 100ºC with 15% reduction in thickness. Non-isothermal rolled alloy (3 mm thickness) was the starting material for further rolling at three different temperatures, such as room temperature, −80 and −190°C with 85 per cent reduction. Microstructural evolution during precipitation and thermo-mechanical processing was studied with the help of optical microscopy and electron microscopy. A potentio-dynamic polarization study was performed to evaluate the corrosion behaviour of Al-12Zn-3Mg-2.5Cu alloy processed in different conditions in 3.5 per cent NaCl solution. Findings There is a distinct evidence that the alloy exhibits varying corrosion resistance by changing its structural features. In fact, the alloy with ultra-fine grained structure exhibits good corrosion resistance than that of alloy in cast. This is attributed to a greater grain boundary region with high dislocation density, and plastic strain adversely affects the corrosion resistance. Originality/value The results obtained by this investigation help in understanding the effect of precipitation hardening and non-isothermal step rolling cum cold/cryo rolling (−80 and −196°C) on corrosion behaviour.

scholarly journals Corrosion Behaviour of Zn-10Al-1.5Cu Alloy

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
C. N. Panagopoulos ◽  
A. G. Tsopani
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behaviour ◽  
Solution Concentration ◽  
Solution Temperature ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nacl Concentration ◽  
Scanning Electron

The corrosion behaviour of Zn-10Al-1.5Cu alloy in NaCl solution was examined. The used NaCl solution concentrations were 1M, 0.3M, and 0.003M for a constant temperature values of 7°C or 25°C or 45°C. The corrosion behaviour of this alloy was investigated under potentiodynamic corrosion conditions. The surface of the corroded alloy specimens was studied with the aid of scanning electron microscopy and X-ray diffraction techniques. It was observed that the increase of NaCl concentration in the corrosion solution for a constant value of temperature led to lower corrosion resistance of the alloy. For a constant value of solution concentration, the increase of solution temperature also led to the decrease of corrosion resistance of the same alloy.

scholarly journals The effect of zinc bath temperature on the morphology, texture and corrosion behaviour of industrially produced hot-dip galvanized coatings

2014 ◽  
Vol 20 (1) ◽  
pp. 41-52 ◽  
Author(s):  
A. Bakhtiari ◽  
M.R. Toroghinejad ◽  
F. Ashrafizadeh
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Texture Component ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Bath Temperature ◽  
X Ray Diffraction ◽  
Zinc Bath ◽  
Compact Structure ◽  
Galvanized Coatings

The purpose of this work is to identify the influence of zinc bath temperature on the morphology, texture and corrosion behavior of hot-dip galvanized coatings. Hot-dip galvanized samples were prepared at temperature in the range of 450-480 °C in steps of 10 °C, which is the conventional galvanizing temperature range in the galvanizing industries. The morphology of coatings was examined with optical microscopy and scanning electron microscopy (SEM). The composition of the coating layers was determined using energy dispersive spectroscopy (EDS) analysis. The texture of the coatings was evaluated using X-ray diffraction. Corrosion behavior was performed using salt spray cabinet test and Tafel extrapolation test. From the experimental results, it was found that increasing the zinc bath temperature affects the morphology of the galvanized coatings provoking the appearance of cracks in the coating structure. These cracks prevent formation of a compact structure. In addition, it was concluded that (00.2) basal plane texture component was weakened by increasing the zinc bath temperature and, conversely, appearance of (10.1) prism component, (20.1) high angle pyramidal component and low angle component prevailed. Besides, coatings with strong (00.2) texture component and weaker (20.1) components have better corrosion resistance than the coatings with weak (00.2) and strong (20.1) texture components. Furthermore, corrosion resistance of the galvanized coatings was decreased by increasing the zinc bath temperature.

Development of Corrosion Resistance Coating for AISI 410 Grade Steel

2015 ◽  
Vol 813-814 ◽  
pp. 135-139 ◽  
Author(s):  
K.G. Girisha ◽  
R. Rakesh ◽  
C. Durga Prasad ◽  
K.V. Sreenivas Rao
Keyword(s):  
Corrosion Resistance ◽  
Plasma Spray ◽  
Corrosion Behaviour ◽  
Steel Substrate ◽  
Salt Spray ◽  
Research Work ◽  
Optical Microscope ◽  
Air Plasma ◽  
Spray Process ◽  
Plasma Spray Process

In this present research work, corrosion behaviour of grit blasted AISI 410 steel substrate coated with NiCr/Al2O3,NiCr/ZrO2 particles was investigated using salt spray test as per ASTM B117. Coatings were prepared using air Plasma spray process. Nickel chromium was used as bond coat for obtaining good fastening between the base metal and coated particles. The microstructures of the coated and un-coated specimens were characterized using scanning electron microscope and optical microscope. Distribution coated particle was found uniform throughout the steel substrate was revealed from SEM microphotographs. The obtained results shows significant improvement in corrosion resistance and micro hardness for NiCr/Al2O3 and NiCr/ZrO2 coating deposited on steel by plasma spray process than the as sprayed base steel substrates.

Effectiveness of Si contents in the steel composition on the corrosion performance of galvanized steel

2017 ◽  
Vol 64 (5) ◽  
pp. 479-485 ◽  
Author(s):  
Zeinab Abdel Hamid ◽  
Sayed Abd El Rehim ◽  
Moustafa Ibrahim
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Social Benefit ◽  
Galvanized Steel ◽  
Chemical Compositions ◽  
Nacl Solution ◽  
Corrosion Performance ◽  
Steel Composition ◽  
Content Type

Purpose The purpose of this work was to investigate the effect of Si content of steel substrate on the performance of the hot-dip galvanized layer. Moreover, the structure of the galvanized layers and the corrosion performance of the galvanized steel in 3.5 per cent NaCl solution have been studied. Design/methodology/approach The galvanized layer has been formed by the hot-dip technique, and the influence of silicon content in the steel composition on the corrosion performance of the galvanized steel was estimated. The surface morphologies and chemical compositions of the coated layers were assessed using scanning electron microscopy and energy-dispersive X-ray analysis, respectively. Potentiodynamic polarization Tafel lines and electrochemical impedance spectroscopy (EIS) tests were used to evaluate the corrosion resistance of the galvanized steel in 3.5 per cent NaCl solution. Findings The results proved that adhere, compact and continuous coatings were formed with steel containing 0.56 Wt.% Si, while cracks and overly thick coatings were obtained with steel containing 1.46 Wt.% Si. Tafel plots illustrated that the corrosion rate of galvanized steel containing 0.08 and 0.56 Wt.% Si was lower than that of the galvanized steel containing 1.46 Wt.% Si. Also, the results of the EIS reveal that the impedance of the galvanized steel containing 0.08 and 0.56 Wt.% Si was the highest and the lowest, respectively, with the steel containing 1.46 Wt.% Si. Social implications Generally, in industry steels containing high amounts of silicon (0.15-0.25 Wt.%) can be galvanized satisfactory either by controlling the temperature (440°C) or adding Ni to the galvanized bath. The low temperature reduces the coating thickness; nickel amount must be controlled to prevent the formation of higher amounts of dross. This study proved that high Si steel of up to 0.56 Wt.% can be galvanized at 460°C without adding Ni to the galvanized bath and form adhere, compact, free cracks and have good corrosion resistance. Consequently, a social benefit can be associated with galvanizing high Si steel, leading to an increase in the cost of the process. Originality/value The results presented in this work are an insight into understanding the hot-dip galvanizing of high Si steel. The corrosion resistance of galvanized steel containing 0.56 Wt.% Si alloys has been considered as a promising behavior. In this work, a consistent assessment of the results was achieved on the laboratory scale.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

Effect of Cr and Zr Addition on the Corrosion Behaviour of Copper in the Chloride Solution

2011 ◽  
Vol 194-196 ◽  
pp. 1253-1256
Author(s):  
Ya Ni Zhang ◽  
Mao Sheng Zheng ◽  
Jie Wu Zhu
Keyword(s):  
Corrosion Resistance ◽  
Chloride Solution ◽  
Corrosion Behaviour ◽  
Pure Copper ◽  
Base Material ◽  
Nacl Solution ◽  
Corrosion Performance ◽  
Zr Addition ◽  
Corrosion Scales ◽  
Better Than

The corrosion behavior of CuCr, CuZr and CuCrZr alloys in NaCl solution is reported in this paper. The corrosion performance has been evaluated in NaCl solution atmosphere. The results show the corrosion resistance of pure copper decrease with the addition of the alloying elements initially. However, in the later exposure stages, the corrosion resistance of CuZr and CuCrZr alloy deteriorates significantly while the corrosion resistance of CuCr alloy is slightly better than that of pure copper. In addition, the results of the electrochemical experiments indicate that the different behavior for the element Cr and Zr in the base material and corrosion scales lead to the change of the corrosion resistance.

Sign in / Sign up

Export Citation Format

Share Document