An investigation of corrosion resistance of HVOF coated ASME SA213 T91 boiler steel in an actual boiler environment

2017 ◽  
Vol 64 (5) ◽  
pp. 499-507 ◽  
Author(s):  
Varinder Pal Singh Sidhu ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Resistance ◽  
Original Research ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Hvof Spraying ◽  
Boiler Steel ◽  
Content Type ◽  
Boiler Environment ◽  
Spraying Process ◽  
Minimum Resistance

Purpose This paper aims to use the high-velocity oxy fuel (HVOF) spraying process for depositing 93(WC–Cr3C2)–7Ni, 75Cr3C2–25NiCr, 83WC–17CO and 86WC–10CO–4Cr coatings on ASME SA213 T91 to study the corrosion resistance of these coatings in an actual boiler environment. Design/methodology/approach The HVOF spraying process was used for depositing 93(WC–Cr3C2)–7Ni, 75Cr3C2–25NiCr, 83WC–17CO and 86WC–10CO–4Cr coatings on ASME SA213 T91. All the coatings obtained are found to be uniform, dense and having thickness between 200 and 250 μm. All the coatings were exposed in an actual boiler environment at 900°C temperature for 10 cycles. Each cycle consisted of 100 h heating followed by 1 h cooling at ambient conditions. X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy techniques were used to analyse corrosion products. Findings All the coated samples were found to be having higher corrosion resistance than the uncoated samples. Among coated specimens, 93(WC–Cr3C2)–7Ni coating has shown maximum and 75Cr3C2–25NiCr coating has shown minimum resistance to corrosion. Originality/value This paper is original research.

Corrosion Behaviour of HVOF Sprayed Coatings on ASME SA213 T22 Boiler Steel in an Actual Boiler Environment

2017 ◽  
Vol 20 ◽  
pp. 1-9 ◽  
Author(s):  
Varinder Pal Singh Sidhu ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Behaviour ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Hvof Spraying ◽  
Boiler Steel ◽  
Nickel Chromium ◽  
Boiler Environment ◽  
Sprayed Coatings ◽  
Spraying Process ◽  
Thin Band

In present study HVOF spraying process had been employed for depositing 93(WC-Cr3C2)-7Ni, 75Cr3C2-25NiCr, 83WC-17CO and 86WC-10CO-4Cr coatings on ASME SA213 T22. All the coatings were found dense and uniform having thickness between 200-250µm. All the coatings on ASME SA213 T22 used in present studies have provided resistance to corrosion in coal fired boiler environment in superheater zone when exposed for 10 cycles at 900°C. Each cycle consists of 100 hours heating followed by 1 hour cooling at ambient conditions. X-ray diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) techniques were used to analyse corrosion products. The results showed that among coated specimens 93(WC-Cr3C2)-7Ni and 75Cr3C2-25NiCr coatings has shown maximum and minimum resistance to corrosion respectively. The better corrosion resistance of 93(WC-Cr3C2)-7Ni coated steel alloys may be attributed to the formation of thin band of oxides of nickel, chromium; and carbides of tungsten.

Improving the hot corrosion resistance of boiler tube steels by detonation gun sprayed coatings in actual boiler of thermal power plant

2019 ◽  
Vol 66 (4) ◽  
pp. 394-402
Author(s):  
Vikramjit Singh ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Power Plants ◽  
Thermal Power ◽  
Boiler Steel ◽  
Content Type ◽  
Boiler Environment ◽  
Detonation Gun ◽  
Sprayed Coatings

Purpose This paper aims to investigate the hot corrosion behavior of Ni-Cr and Cr3C2-NiCr coatings, deposited on T11, P91 boiler steels by detonation gun spray coating (D-Gun) process to enhance high temperature corrosion resistance. Design/methodology/approach Hot corrosion studies were conducted in secondary super heater zone of boiler at 900 °C for 10 cycles on bare and D-Gun coated steel specimens. The microhardness and porosity values of as-sprayed coatings were measured before exposing the specimens in the boiler environment. Each cycle consisted 100 h of heating in the boiler environment followed by 20 min of cooling in air. The weight change measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction, SEM techniques were used to analyze the corroded specimens. Findings Uncoated boiler steel experienced higher weight loss. The Cr3C2-NiCr coating was found to be more protective than Ni-Cr coating. The phases revealed the formation of oxide scale on coated specimens, mainly consist of nickel and chromium, which are reported to be protective against the hot corrosion. Originality/value There is very limited reported literature on hot corrosion behavior of Ni-Cr and Cr3C2-NiCr coatings deposited on the T11 and P91 substrates by detonation gun (D-gun) spray technique. T11 and P91 alloy steels have been chosen for this study because these two alloys are used to manufacture boiler tubes used in Indian thermal power plants.

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.

Electrochemical behavior and corrosion resistance of electrodeposited nano-particles Zn-Co-Fe alloy

2015 ◽  
Vol 63 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Mortaga Abou-Krisha ◽  
Fawzi Assaf ◽  
Omar Alduaij ◽  
Abdulrahman G Alshammari ◽  
Fatma El-Sheref
Keyword(s):  
Corrosion Resistance ◽  
Ternary Alloy ◽  
Binary Alloys ◽  
Linear Sweep Voltammetry ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
Surface Appearance ◽  
Content Type ◽  
X Ray ◽  
Anticorrosion Properties

Purpose – The purpose of this study was to compare the electrodeposition behavior and corrosion resistance of ternary and binary alloys. Design/methodology/approach – Potentiodynamic polarization resistance measurement and anodic linear sweep voltammetry techniques were used for the corrosion study. The surface morphology and chemical composition of the deposits were examined using scanning electron microscopy and atomic absorption spectroscopy, respectively. The phase structure was characterized by X-ray diffraction analysis. Electrodeposition behavior was carried out using cyclic voltammetry and galvanostatic techniques. Findings – It was found that the obtained ternary alloy exhibited better corrosion resistance and a more-preferred surface appearance compared to the binary alloys that were electrodeposited under similar conditions. Research limitations/implications – The ternary alloy showed better anticorrosion properties compared to binary deposits that were electroplated successfully from the plating baths. The Zn-Co-Fe alloy could be used advantageously in industry because the ternary alloy exhibits the collective properties of the binary alloys in one alloy via the electrodeposition of Zn-Ni-Co alloy. Social implications – Increasing the corrosion resistance implies to social economic increases. Originality/value – To date, the electrodeposition of Zn-Co-Fe alloy was studied in only a small number of articles. It was found that the presence of Co or Fe could provide a useful coating on the steel that would reduce its susceptibility to corrosion attack.

Characterization and hot corrosion behavior of D-gun sprayed Cr2O3-75% Al2O3 coated ASTM-SA210-A1 boiler steel in molten salt environment

2017 ◽  
Vol 64 (5) ◽  
pp. 515-528 ◽  
Author(s):  
Amita Rani ◽  
Niraj Bala ◽  
C.M. Gupta
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Molten Salt ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Degradation Mechanism ◽  
Effective Diffusion ◽  
Boiler Steel ◽  
Content Type ◽  
Scanning Electron

Purpose Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. The present work aims to investigate the hot corrosion resistance of detonation gun sprayed (D-gun) Cr2O3-75 per cent Al2O3 ceramic coating on ASTM-SA210-A1 boiler steel. Design/methodology/approach The coating exhibits nearly uniform, adherent and dense microstructure with porosity less than 0.8 per cent. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and coated boiler steel in molten salt environment (Na2SO4-60 per cent V2O5) at high temperature 900°C for 50 cycles. The corrosion products are analyzed by using X-ray diffraction, scanning electron microscopy (SEM) and field emission scanning electron microscope/energy-dispersive analysis (EDAX) to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. Findings During investigations, it was found that the Cr2O3-75 per cent Al2O3 coating on Grade A-1 boiler steel is found to be very effective in decreasing the corrosion rate in the molten salt environment at 900°C. The coating has shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. Thus, coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate boiler steel. Research limitations/implications Therefore, it is concluded that the better hot corrosion resistance of the coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains and the flat splat structures in the coating; as compared to the bare substrate under cyclic conditions. Practical implications This research is useful for coal-fired boilers and other power plant boilers. Social implications This research is useful for power generation plants. Originality/value There is no reported literature on hot corrosion behavior of Cr2O3-75 per cent Al2O3 coating deposited on the selected substrates by D-gun spray technique. The present work has been focused to study the influence of the Cr2O3-75 per cent Al2O3 coating developed with D-gun spraying technique on high temperature corrosion behavior of ASTM-SA210-A-1 boiler steel in an aggressive environment of Na2SO4-60 per cent V2O5 molten salt at 900°C under cyclic conditions.

The influence of hexamethylenetetramine on the structure and corrosion resistance of phosphate coating on AZ31 magnesium alloy

2016 ◽  
Vol 63 (3) ◽  
pp. 161-165 ◽  
Author(s):  
Jiansan Li ◽  
Yali Li ◽  
Yanqin Chen ◽  
Jiawei Sun ◽  
Chunxiao Wang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Design Methodology ◽  
Energy Dispersive Spectrometry ◽  
Electrochemical Impedance ◽  
Phosphate Coating ◽  
X Ray Diffraction ◽  
Content Type ◽  
X Ray ◽  
Phosphate Coatings

Purpose This paper aims to report the influence of hexamethylenetetramine (HMTA) on phosphate coatings formed on AZ31 magnesium alloys. Design/methodology/approach These phosphate coatings were obtained by immersing magnesium alloys in phosphate baths with HMTA. The morphology and composition of the phosphate coatings were investigated via scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. Findings The phosphate coatings were mainly composed of CaHPO4·2H2O. The HMTA concentration in the phosphate bath influenced the crystallization and corrosion resistance of the phosphate coating. Originality/value The polarization curve shows that the anti-corrosion qualities of the phosphate coating were optimal when the HMTA concentration was 1.0 g/L in the phosphate bath. Electrochemical impedance spectroscopy (EIS) shows that the electrochemical impedances increased gradually when the HMTA concentration varied from 1.0 to 3.0 g/L.

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.

HVOF Diamalloy 2002 coating of steel surface: electrochemical corrosion resistance

2015 ◽  
Vol 67 (2) ◽  
pp. 119-123
Author(s):  
B. S. Yilbas ◽  
I.-H. Toor ◽  
F. Patel ◽  
Y. Al-Shehri ◽  
M. A. Baig
Keyword(s):  
Corrosion Resistance ◽  
Gas Turbines ◽  
Steel Surface ◽  
Electrochemical Corrosion ◽  
Experimental Investigations ◽  
Hvof Spraying ◽  
Content Type ◽  
Hvof Coating ◽  
Model Studies ◽  
Deep Pit

Purpose – The purpose of this paper is to investigate the corrosion resistance of high velocity oxy-fuel (HVOF)-sprayed Diamalloy 2002 coating on carbon steel. The coating microstructure is examined in line with the corrosion resistance. Design/methodology/approach – HVOF spraying of coating is achieved, and the coating response to electrolytic solution is measured experimentally in terms of corrosion resistance. Findings – HVOF coating improves the corrosion resistance of the substrate such that the corrosion rate of the substrate is 7.1 mpy and the coating results in 4.5 mpy. However, presence of deep pit sites at the surface suggests the occurrence of preferential corrosion around the splat boundaries. In addition, closely spaced surface texture peaks act as crevice corrosion centers at the surface while initiating the formation of deep pit sites. Research limitations/implications – This study is limited by experimental investigations. In future, it may be extended to include model studies. Practical implications – The findings of this study are very useful for those working in the coating industry. However, HVOF coating is limited to high temperature protection in harsh environments. Social implications – It is useful for the power industry, particularly for gas turbines. Originality/value – It is an original work and describes the corrosion resistance of the coating surface. It is found that the coating improved the corrosion resistance of the steel surface.

Influence of potential on the structure and properties of microarc oxidation coating on Mg alloy

2008 ◽  
Vol 55 (5) ◽  
pp. 264-269 ◽  
Author(s):  
Deng Shu‐hao ◽  
Yi Dan‐qing ◽  
Gong Zhu‐qing ◽  
Su Yu‐chang
Keyword(s):  
Corrosion Resistance ◽  
Microarc Oxidation ◽  
Oxidation Potential ◽  
Structure And Properties ◽  
Micro Hardness ◽  
External Layer ◽  
X Ray Diffraction ◽  
Content Type ◽  
Constant Potential ◽  
Composition Structure

PurposeTo obtain an optimized microarc oxidation (MAO) coating on magnesium alloy from an environmentally‐friendly electrolyte free of Cr6 +  and PO43− and to investigate the influence of oxidation potential on the morphology, composition, structure, and other properties such as micro‐hardness and corrosion resistance.Design/methodology/approachA constant potential regime was applied to produce the coatings and scanning electron microscopy, energy dispersive spectroscope, X‐ray diffraction, hardness testing and electrochemical methods were used to study coating properties.FindingsThe results clearly show that oxidation potential plays an important role in the formation of coating structure and properties. The MAO coating is smooth and white and consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, the content of Al and Si increase with operated potential. The inner layer is compact and the content of Al and Si are lower than are those of the external layer. The coating is composed of several phases: the main phase is MgAl2O4/MgO, and the minor phase is Al2O3/SiO2 when the potential is higher. The micro‐hardness of the coating obtained a maximum at a potential of 45 V, as does the corrosion resistance.Originality/valueThis paper provides information relating to MAO technology and the morphology, structure and properties of MAO coatings.

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.

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