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Satya Prakash - One of the best experts on this subject based on the ideXlab platform.
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High Temperature Corrosion behaviour of superalloys under actual waste incinerator environment
Engineering Failure Analysis, 2016Co-Authors: Lalit Ahuja, Deepa Mudgal, Divya Bhatia, Surendra Singh, Satya PrakashAbstract:Abstract In the present study, three superalloys viz. Superni 718, Superni 600 and Superco 605 were hung inside the secondary chamber of actual medical waste incinerator where the Temperature is more than 1050 °C. Burning of medical waste produces very corrosive environment at High Temperature which can degrade the components of construction. Hence the three superalloys were kept for 1000 h inside the chamber. Corrosion rate has been calculated in mpy. Corrosion products so produced were characterized using SEM/EDS and XRD technique. It was observed that both the Nickel based superalloys showed better Corrosion resistance than the cobalt based superalloy under the given environment.
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Comparative High-Temperature Corrosion Behavior of Ni-20Cr Coatings on T22 Boiler Steel Produced by HVOF, D-Gun, and Cold Spraying
Metallurgical and Materials Transactions A, 2014Co-Authors: Gagandeep Kaushal, Harpreet Singh, Niraj Bala, Narinder Kaur, Satya PrakashAbstract:To protect materials from surface degradations such as wear, Corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and High-Temperature Corrosion of Ni-20Cr coatings deposited on T22 boiler steel by High velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings’ microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the Corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings.
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High Temperature Corrosion studies on friction welded low alloy steel and stainless steel in air and molten salt environment at 650 c
Materials & Design, 2012Co-Authors: N Arivazhagan, Satya Prakash, S Narayanan, S P Singh, G M ReddyAbstract:Abstract The investigation on High-Temperature Corrosion resistance of the weldments is necessary for prolonged service lifetime of the components used in corrosive environments. This paper reports on the performance of friction welded low alloy steel AISI 4140 and stainless steel AISI 304 in air as well as molten salt environment of Na2SO4–60%V2O5 and NaCl–50%Na2SO4 at 650 °C. This paper reports several studies carried out for characterizing the weldments Corrosion behavior. Initially thermogravimetric technique was used to establish the kinetics of Corrosion. For analyzing the Corrosion products, X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe micro analysis techniques were used. From the results of the experiments, it is observed that the weldments suffered accelerated Corrosion in NaCl–Na2SO4 environment and showed spalling/sputtering of the oxide scale. Furthermore, Corrosion resistance of weld interface was found to be lower than that of parent metals in molten salt environment. Weight gain kinetics in air oxidation studies reveals a steady-state parabolic rate law while the kinetics with salt deposits displays multi-stage growth rates. Moreover NaCl is the main corrosive species in High Temperature Corrosion, involving mixtures of NaCl and Na2SO4 which is responsible for formation of internal attack.
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High Temperature Corrosion studies of hvof sprayed cr3c2 nicr coating on sae 347h boiler steel
Journal of Thermal Spray Technology, 2009Co-Authors: Manpreet Kaur, Harpreet Singh, Satya PrakashAbstract:Cr3C2-NiCr coating was deposited on SAE-347H boiler steel by High velocity oxy fuel (HVOF) spray process. Subsequently, High-Temperature Corrosion behavior of the bare and coated boiler steel was investigated at 700 °C for 50 cycles in Na2SO4-82Fe2(SO4)3 molten salt, as well as air environments. Weight-change measurements after each cycle were made to establish the kinetics of Corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy dispersive spectroscopy, and x-ray mapping analyses were performed on the exposed samples to analyze the oxidation products. The bare 347H steel suffered accelerated oxidation during exposure at 700 °C in the air as well as the molten salt environment in comparison with its respective coated counterparts. The HVOF-spray Cr3C2-NiCr coating was found to be successful in maintaining its adherence in both the environments. The surface oxide scales were also found to be intact. The formation of chromium rich oxide scale might have contributed for the better hot Corrosion/oxidation resistance in the coated steel.
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hot Corrosion of some superalloys and role of High velocity oxy fuel spray coatings a review
Surface & Coatings Technology, 2005Co-Authors: T S Sidhu, R D Agrawal, Satya PrakashAbstract:Abstract Hot Corrosion is a serious problem in power generation equipment, gas turbines, internal combustion engines, fluidized bed combustion, industrial waste incinerators and paper and pulp industries. No alloy is immune to hot Corrosion attack indefinitely although there are some alloy compositions that require a long initiation time at which the hot Corrosion process moves from the initiation stage to the propagation stage. Superalloys have been developed for High-Temperature applications. However, these alloys are not always able to meet both the High-Temperature strength and High-Temperature Corrosion resistance simultaneously, so the need to be protected from Corrosion. The High-Temperature protecting system must meet several criteria, provide adequate environment resistance, be chemically and mechanically compatible with the substrate, be practically applicable, reliable and economically viable. This paper briefly reviews the hot Corrosion of some Ni- and Fe-base superalloys to understand the phenomenon. Comprehensive reviews of the Corrosion of coatings have appeared regularly since early 1970; the purpose of this paper is not to repeat the published materials but rather to focus on research trends and to point out some research prospects. High-velocity oxy-fuel (HVOF) spraying is a new and rapidly developing technology in combating High-Temperature Corrosion and is now challenging the vacuum plasma spraying technique (VPS), which is very expensive (capital costs approximately 2 million US$). HVOF coatings have very low porosity, High hardness, High abrasive resistance, good wear resistance with a strong ability to resist High-Temperature Corrosion resistance. The purpose here is to summarize the performance of such coatings on various substrates. The effect of coatings thickness, residual stresses induced in the substrates, pre and postheat treatment of the HVOF coatings have been reviewed with the aims of summarizing their High-Temperature Corrosion resistance properties.
Reza Jafari - One of the best experts on this subject based on the ideXlab platform.
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High Temperature Corrosion performance of hvaf sprayed nicr nial and nicraly coatings with alkali sulfate chloride exposed to ambient air
Corrosion Science, 2019Co-Authors: Reza Jafari, Esmaeil SadeghiAbstract:Abstract The High-Temperature Corrosion of High velocity air-fuel (HVAF) thermal spray Ni21Cr, Ni5Al, and Ni21Cr7AlY coatings was investigated at 600 °C for 168 h in ambient air under KCl and 50-50 mol% KCl–K2SO4 salts. Chlorination-oxidation cycle and breakdown of the Corrosion products layer were the dominant Corrosion mechanism in the chromia-forming Ni21Cr and Ni21Cr7AlY coatings exposed to KCl. KCl–K2SO4 was less corrosive to the chromia-forming coatings as K2SO4 was less reactive to the protective Cr-rich oxide. The alumina-forming NiAl exhibited a better Corrosion performance under KCl, though it partially suffered from selective sulfidation when exposed to the mixed salt.
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kcl induced High Temperature Corrosion behavior of hvaf sprayed ni based coatings in ambient air
Journal of Thermal Spray Technology, 2018Co-Authors: Reza Jafari, Esmaeil Sadeghimeresht, Taghi Shahrabi Farahani, Matti Huhtakangas, Nicolaie Markocsan, Shrikant V JoshiAbstract:KCl-induced High Temperature Corrosion behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5Al, Ni21Cr7Al1Y, and Ni21Cr9Mo) under KCl deposit has been investigated in ambient air at 600°C up ...
T Mantyla - One of the best experts on this subject based on the ideXlab platform.
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High Temperature Corrosion of coatings and boiler steels below chlorine containing salt deposits
Corrosion Science, 2004Co-Authors: M A Uusitalo, Petri Vuoristo, T MantylaAbstract:High Temperature Corrosion tests were performed on low-alloyferritic steel and austenitic stainless steel, five High velocityoxy -fuel (HVOF) coatings, a laser cladding, and a diffusion chromized steel. Test conditions simulated superheater conditions of biofuel-fired boiler. The samples were exposed to synthetic salt containing 40 wt% K2SO4, 40 wt% Na2SO4, 10 wt% KCl, and 10 wt% NaCl. Exposures were carried out in oxidizing and in reducing atmospheres. The test Temperature was 550 � C and the test duration was 100 h. Corrosion was extremely severe in oxidizing conditions because of active oxidation. In reducing atmosphere Corrosion was retarded due to depletion of chlorine in the scales byevaporation of metal chlorides, and formation of a layer rich in chromium, sodium, sulfur, and oxygen adjacent to the metal surface. The Corrosion resistance of coatings was determined bycomposition and microstructure. Oxides at splat boundaries were attacked bychlorine, and chlorine was able to penetrate through the coatings along splat boundaries. � 2003 Elsevier Ltd. All rights reserved.
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High Temperature Corrosion of coatings and boiler steels in oxidizing chlorine containing atmosphere
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: M A Uusitalo, Petri Vuoristo, T MantylaAbstract:Abstract High Temperature Corrosion tests were performed on ferritic and austenitic boiler steels, five High velocity oxy-fuel (HVOF) coatings, laser-melted HVOF coating, and diffusion chromized steel. Synthetic atmosphere simulating biofuel combustion was created for the tests. The tests were performed in oxidizing atmosphere containing 500 vppm HCl, 20% H2O, 3% O2, and Ar as a balance. The test Temperature was 550 °C and the test duration was 1000 h. The Corrosion resistance of steels was determined by alloy content. Homogeneous and dense coatings with High chromium content performed well and protected the substrate material. Corrosive species were able to penetrate through some of the HVOF coatings and attack the substrate via interconnected network of voids and oxides at splat boundaries.
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High Temperature Corrosion of coatings and boiler steels in reducing chlorine containing atmosphere
Surface & Coatings Technology, 2002Co-Authors: M A Uusitalo, Petri Vuoristo, T MantylaAbstract:Abstract Unacceptably High Corrosion rates are often experienced, when chlorine-containing fuels are combusted. Reducing conditions that may occur in various boilers accelerate Corrosion even further. Protective oxide scales are not formed on low-alloy steels if partial pressure of oxygen is too low. Materials rich in oxide formers, such as chromium and aluminum, are needed to resist Corrosion in reducing combustion atmospheres, but processibility of such bulk alloys is very limited. Various coating technologies are considered as potential solution for Corrosion problems in High Temperature combustion environments with low partial pressure of oxygen. High Temperature Corrosion tests were performed on one ferritic boiler steel, one austenitic boiler steel, five High velocity oxy-fuel (HVOF) coatings, one laser-melted HVOF coating, and one diffusion chromized steel. Synthetic atmosphere simulating reducing conditions in combustion of chlorine-containing fuels was created for the tests. The test atmosphere contained 500 ppm HCl, 600 ppm H 2 S, 20% H 2 O, 5% CO, and Ar as a balance. The test Temperature was 550 °C and the test duration was 1000 h. Corrosion resistance of steels and homogeneous coatings was mainly determined by chromium content. Homogeneous and dense coatings with High chromium content performed well and were able to protect the substrate. Some of the HVOF coatings were attacked by corrosive species through interconnected network of voids and oxides at splat boundaries.
Harpreet Singh - One of the best experts on this subject based on the ideXlab platform.
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Comparative High-Temperature Corrosion Behavior of Ni-20Cr Coatings on T22 Boiler Steel Produced by HVOF, D-Gun, and Cold Spraying
Metallurgical and Materials Transactions A, 2014Co-Authors: Gagandeep Kaushal, Harpreet Singh, Niraj Bala, Narinder Kaur, Satya PrakashAbstract:To protect materials from surface degradations such as wear, Corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and High-Temperature Corrosion of Ni-20Cr coatings deposited on T22 boiler steel by High velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings’ microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the Corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings.
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role of detonation gun spray cr3c2 nicr coating in improving High Temperature Corrosion resistance of sae 213 t22 and sae 347h steel in presence of na2so4 82 fe2 so4 3 salt deposits
Surface Engineering, 2010Co-Authors: Manpreet Kaur, Harpreet Singh, S PrakashAbstract:AbstractCr3C2–NiCr coatings were sprayed on SAE–213–T22 and SAE–347H boiler steels by detonation gun spray process. High Temperature Corrosion studies were conducted on the uncoated as well as detonation gun sprayed specimens in a molten salt environment at 700°C under cyclic conditions. The molten salt comprising Na2SO4–82%Fe2(SO4)3 was applied on the specimens as a deposit. The weight change technique was used to establish kinetics of the Corrosion. X-ray diffraction, field emission scanning electron microscopy/energy dispersive spectroscopy and X-ray mapping techniques were used to analyse the Corrosion products. SAE–213–T22 steel suffered an accelerated Corrosion in the form of intense spalling of its oxide scale, whereas SAE–347H steel exhibited only marginal spallation in the form of fine powder. The Cr3C2–NiCr coating showed good adherence to the boiler steels during the exposure with no tendency for spallation of its oxide scale. The coating was found to be successful in developing resistance agai...
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High Temperature Corrosion Behavior of Cold Spray Ni-20Cr Coating on Boiler Steel in Molten Salt Environment at 900 °C
Journal of Thermal Spray Technology, 2009Co-Authors: Harpreet SinghAbstract:Cold spray is an emerging technology that produces High density metallic coatings with low oxide contents and High thermal conductivity, which makes them ideal for High Temperature Corrosion resistance. In the current investigation, Ni-20Cr alloy powder was deposited on SA 516 boiler steel (0.19C-1.07Mn-0.020S-0.25P-0.010Si-balance Fe) by cold spray process. Oxidation kinetics was established for the uncoated and cold spray Ni-20Cr coated boiler steel in an aggressive environment of Na2SO4-60%V2O5 at 900 °C for 50 cycles by the weight change technique. X-ray diffraction, FE-SEM/EDAX, and x-ray mapping techniques were used to analyze the oxidation products. Uncoated steel suffered Corrosion in the form of intense spalling and peeling of its oxide scale, which may be due to the formation of unprotective Fe2O3 oxides. The Ni-20Cr coating was successful in reducing the weight gain of the steel by 87.2% which may be due to the formation of oxides of nickel and chromium.
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High Temperature Corrosion studies of hvof sprayed cr3c2 nicr coating on sae 347h boiler steel
Journal of Thermal Spray Technology, 2009Co-Authors: Manpreet Kaur, Harpreet Singh, Satya PrakashAbstract:Cr3C2-NiCr coating was deposited on SAE-347H boiler steel by High velocity oxy fuel (HVOF) spray process. Subsequently, High-Temperature Corrosion behavior of the bare and coated boiler steel was investigated at 700 °C for 50 cycles in Na2SO4-82Fe2(SO4)3 molten salt, as well as air environments. Weight-change measurements after each cycle were made to establish the kinetics of Corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy dispersive spectroscopy, and x-ray mapping analyses were performed on the exposed samples to analyze the oxidation products. The bare 347H steel suffered accelerated oxidation during exposure at 700 °C in the air as well as the molten salt environment in comparison with its respective coated counterparts. The HVOF-spray Cr3C2-NiCr coating was found to be successful in maintaining its adherence in both the environments. The surface oxide scales were also found to be intact. The formation of chromium rich oxide scale might have contributed for the better hot Corrosion/oxidation resistance in the coated steel.
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High Temperature Corrosion studies of hvof sprayed cr 3 c 2 nicr coating on sae 347h boiler steel
Journal of Thermal Spray Technology, 2009Co-Authors: Manpreet Kaur, Harpreet Singh, S PrakashAbstract:Cr3C2-NiCr coating was deposited on SAE-347H boiler steel by High velocity oxy fuel (HVOF) spray process. Subsequently, High-Temperature Corrosion behavior of the bare and coated boiler steel was investigated at 700 °C for 50 cycles in Na2SO4-82Fe2(SO4)3 molten salt, as well as air environments. Weight-change measurements after each cycle were made to establish the kinetics of Corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy dispersive spectroscopy, and x-ray mapping analyses were performed on the exposed samples to analyze the oxidation products. The bare 347H steel suffered accelerated oxidation during exposure at 700 °C in the air as well as the molten salt environment in comparison with its respective coated counterparts. The HVOF-spray Cr3C2-NiCr coating was found to be successful in maintaining its adherence in both the environments. The surface oxide scales were also found to be intact. The formation of chromium rich oxide scale might have contributed for the better hot Corrosion/oxidation resistance in the coated steel.
Patrik Yrjas - One of the best experts on this subject based on the ideXlab platform.
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The influence of flue gas Temperature on lead chloride induced High Temperature Corrosion
Fuel, 2017Co-Authors: Hanna Kinnunen, Merja Hedman, Mikko Uusitalo, Daniel Lindberg, Markus Engblom, Sonja Enestam, Patrik YrjasAbstract:Abstract Firing of waste-based fuels increases the risk for heavy metal-induced Corrosion in the furnace walls and in other low-Temperature heat transfer surfaces, such as primary superheaters. Lead-containing compounds, especially alkali lead chlorides, have been detected in the boiler water walls, causing severe Corrosion. Corrosion rate of chlorine-induced Corrosion is known to be dependent on the material Temperature and the objective of this work was to study the influence of the flue gas Temperature on lead chloride-induced Corrosion. The experiments were carried out with full-scale Corrosion probe and deposit probe measurements in a recycled wood firing CFB boiler. The material used in the Corrosion probe measurements was low alloy steel EN10216-2 16Mo3 and the material Temperature was adjusted to 360 °C. Two Corrosion and deposit probes were used in different locations in order to expose the probes towards hot, 800 °C, and cooler, 490 °C, flue gas Temperatures. Changes of the wall thicknesses were measured and the samples were analysed with SEM/EDS and XRD for more detailed deposit characterisation. Corrosion was detected in both the hot and the cooler flue gas samples. A low melting (T 0 = 368 °C) alkali-lead-chloride mixture was identified. Findings from these measurements strongly indicate this mixture to be the Corrosion-causing compound at both flue gas Temperatures. However, the Corrosion rate was Higher in the hot flue gas sample compared to the cooler flue gas sample. A much steeper deposit Temperature gradient was calculated for the hot flue gas sample, suggesting that the alkali-lead-chloride mixture is in the molten form. These findings, together with the Higher proportion of the present alkali-lead-chloride mixture, are the potential factors for the Higher Corrosion rate in the hot flue gas sample compared to the cooler flue gas sample.
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High Temperature Corrosion of boiler waterwalls induced by chlorides and bromides part 1 occurrence of the corrosive ash forming elements in a fluidised bed boiler co firing solid recovered fuel
Fuel, 2011Co-Authors: Pasi Vainikka, Patrik Yrjas, Dorota Bankiewicz, A Frantsi, Jaani Silvennoinen, Janne Hannula, Mikko HupaAbstract:In waste fired boilers High Temperature Corrosion has often been attributed to zinc and lead chlorides. In addition, bromine induced High Temperature Corrosion has been earlier observed in a bubbling fluidised bed (BFB) boiler co-firing solid recovered fuel (SRF) with bark and wastewater sludge. In Part 1 of this work a measurement campaign was undertaken to determine the occurrence of Cl, Br, Zn and Pb in the fuel, in the combustion gases as well as in the deposits on the boiler waterwalls. It was observed that Cl, Br, Zn and Pb originate to a large extent from the SRF, they are vaporised in the furnace, and may form waterwall deposits. This, complemented by fluctuations between oxidising and reducing atmosphere resulted in rapid Corrosion of the waterwall tubes. Concentrations of Cl, Br, Zn and Pb in the fuel, in the furnace vapours and in the deposits are reported in this work. As there is lack of published data on the bromine induced High Temperature Corrosion, laboratory scale Corrosion tests were carried out to determine the relative corrosiveness of chlorine and bromine and these results will be reported in Part 2 of this work. Furthermore, the forms of Cl, Br, Zn and Pb in the combustion gases as well as in the waterwall deposits were estimated by means of thermodynamic equilibrium modelling and these results will also be discussed in Part 2.
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High Temperature Corrosion of superheater tube materials exposed to zinc salts
Energy & Fuels, 2009Co-Authors: Dorota Ankiewicz, Patrik Yrjas, Mikko HupaAbstract:It is of great importance nowadays to develop a deeper understanding of Corrosion phenomena occurring in energy conversion processes in thermal power plant technology systems. The superheaters in biofuels and waste-firing boilers are often exposed to aggressive compounds, which strongly decrease their durability. Waste incinerators and demolition wood-fired boiler deposits usually contain relatively High concentrations of heavy metals, such as Zn and Pb compounds. These elements, in combination with chlorine, can decrease the first melting point of the deposits. Consequently, molten salt attack by these metal chlorides can occur, and the Corrosion will be more severe than gas-phase Corrosion. In this study, laboratory-scale, High-Temperature Corrosion tests have been carried out. Well-characterized salt mixtures consisting of zinc and potassium chlorides and sulfates (K 2 SO 4 , KCl, and ZnCl 2 ) were used for Corrosion testing. Tests were performed for three commercially used steam tube materials. The metal specimens covered with salts were exposed to Temperatures ranging from 350 to 600 °C for 168 h. After heat treatment, the specimens were analyzed using a scanning electron microscope and energy-dispersive X-ray (SEM-EDX) to determine the oxide layer thickness and the elemental distribution in the oxide scale. The results showed enhanced Corrosion of low alloy steel with an increasing Temperature and increasing amount of ZnCl 2 in the salt mixture.