The Experts below are selected from a list of 12471 Experts worldwide ranked by ideXlab platform
R D Agrawal - One of the best experts on this subject based on the ideXlab platform.
-
a comparative study of Hot Corrosion resistance of hvof sprayed nicrbsi and stellite 6 coated ni based superalloy at 900 c
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Abstract A comparative study was carried out to evaluate the Hot Corrosion resistance of NiCrBSi and Stellite-6 coated nickel-based superalloy Superni 600 (15.5Cr–10Fe–0.5Mn–0.2C–balance Ni) in the molten salt environment of Na 2 SO 4 –60%V 2 O 5 salt mixture at 900 °C under cyclic conditions. Hot Corrosion experiments were performed for 50 cycles, each cycle consisting of 1 h heating in the laboratory tube furnace followed by 20 min cooling in the open air. The thermogravimetric technique was used to establish the kinetics of Corrosion. The morphology, phase composition and element concentration of the Corrosion products were detected using the combined techniques of X-ray diffractometry (XRD), scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) and electron probe micro analyzer (EPMA). The Hot Corrosion resistance of NiCrBSi coating has been found to be better than that of Stellite-6 coating. The Hot Corrosion resistance of both the coatings has been attributed to the formation of oxides of chromium, silicon and nickel along with spinels of nickel–chromium and cobalt–chromium. These oxides seal/plug the pores and splat boundaries, and act as diffusion barriers to the inward diffusion of corroding species.
-
Hot Corrosion studies of hvof nicrbsi and stellite 6 coatings on a ni based superalloy in an actual industrial environment of a coal fired boiler
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Hot Corrosion of boiler tubes used for super-heaters and re-heaters in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. Attempts to decrease the maintenance costs of these components have increased interest in shielding them with protective coatings. The present investigation is an attempt to evaluate the Hot Corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed NiCrBSi and Stellite-6 coatings on a nickel-based superalloy in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 900 °C. Experiments were carried out for 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Both the coatings deposited on Ni-based superalloy imparted better Hot Corrosion resistance than the uncoated one. The Stellite-6 coated superalloy performed better than the NiCrBSi coated in the given environment.
-
Hot Corrosion studies of hvof nicrbsi and stellite 6 coatings on a ni based superalloy in an actual industrial environment of a coal fired boiler
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Hot Corrosion of boiler tubes used for super-heaters and re-heaters in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. Attempts to decrease the maintenance costs of these components have increased interest in shielding them with protective coatings. The present investigation is an attempt to evaluate the Hot Corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed NiCrBSi and Stellite-6 coatings on a nickel-based superalloy in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 900 °C. Experiments were carried out for 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Both the coatings deposited on Ni-based superalloy imparted better Hot Corrosion resistance than the uncoated one. The Stellite-6 coated superalloy performed better than the NiCrBSi coated in the given environment.
-
Hot Corrosion studies of hvof sprayed cr3c2 nicr and ni 20cr coatings on nickel based superalloy at 900 c
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Abstract The high velocity oxy-fuel (HVOF) process is widely adopted by many industries due to its flexibility, cost effectiveness, handiness for use and the superior quality of the coatings produced. The present work is a comparative study of HVOF sprayed Cr3C2–NiCr and Ni–20Cr coatings on a Ni-based superalloy in a molten salt environment of Na2SO4–60%V2O5 at 900 °C under cyclic conditions. The thermogravimetric technique was used to establish the kinetics of Corrosion. X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe microanalysis techniques were used to analyse the Corrosion products. The Hot Corrosion resistance of Ni–20Cr coating was better than Cr3C2–NiCr coating. The Hot Corrosion resistance of both coatings may be attributed to the formation of oxides and spinels of nickel and chromium. These oxides might have blocked the pores and splat boundaries, and acted as diffusion barriers to the inward diffusion of oxidizing species.
-
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.
S Prakash - One of the best experts on this subject based on the ideXlab platform.
-
high temperature cyclic oxidation and Hot Corrosion behaviours of superalloys at 900 c
Bulletin of Materials Science, 2010Co-Authors: Subhash Kamal, R Jayaganthan, S PrakashAbstract:Oxidation and Hot Corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75, Superni 718 and Superfer 800H superalloys (Midhani grade), are the prominent materials for the high temperature applications. It is very essential to investigate the degradation mechanism of superalloys due to oxidation and Hot Corrosion and substantiate the role of alloying elements for the formation of protective oxide films over the surface of the superalloys. Therefore, the present work investigates the oxidation and Hot Corrosion behaviour of superalloys exposed to air and molten salt (Na2SO4–60% V2O5) environment, respectively, at 900°C under cyclic conditions. The weight change measurements made on the superalloys during the experiments are used to determine the kinetics of oxidation and Hot Corrosion. X-ray diffraction (XRD), X-ray mapping and field emission scanning electron microscope (FESEM, FEI, Quanta 200F company) with EDAX Genesis software attachment, made in Czech Republic are used to characterize the corroded products of the superalloys. It is observed that the formation of scale rich in Cr2O3, NiO and spinel NiCr2O4 has contributed for the better oxidation and Hot Corrosion resistance of Superni 75; whereas relatively lesser Hot Corrosion resistance of Superfer 800H is due to the formation of non-protective oxides of iron and sulphides of iron and nickel. The parabolic rate constants calculated for the superalloys show that the Corrosion rate is minimum in air as compared to molten salt environment.
-
evaluation of Hot Corrosion behaviour of hvof sprayed ni 5al and nicral coatings in coal fired boiler environment
Surface Engineering, 2010Co-Authors: R A Mahesh, R Jayaganthan, S PrakashAbstract:Abstract Hot Corrosion was recognised as a serious problem in connection with the degradation of fireside boiler tubes in coal fired steam generating plants. It is one of the most deleterious forms of surface degradation which can lead to the loss of mechanical strength and catastrophic failure of structural and engineering components. In the present investigation, an attempt has been made to evaluate the Hot Corrosion behaviour of high velocity oxyfuel (HVOF) sprayed Ni–5Al and NiCrAl coatings on iron based superalloy in an actual coal fired boiler environment. The coated specimens were hung in the low temperature superheater zone (∼700°C) of a coal fired boiler. The studies were carried out for 10 cycles each cycle consisting of exposing the coated specimens for 100 h followed by 1 h cooling to ambient conditions. NiCrAl coated specimen provided better resistance to Hot Corrosion than Ni–5Al coated specimen in the given environment.
-
a comparative study of Hot Corrosion resistance of hvof sprayed nicrbsi and stellite 6 coated ni based superalloy at 900 c
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Abstract A comparative study was carried out to evaluate the Hot Corrosion resistance of NiCrBSi and Stellite-6 coated nickel-based superalloy Superni 600 (15.5Cr–10Fe–0.5Mn–0.2C–balance Ni) in the molten salt environment of Na 2 SO 4 –60%V 2 O 5 salt mixture at 900 °C under cyclic conditions. Hot Corrosion experiments were performed for 50 cycles, each cycle consisting of 1 h heating in the laboratory tube furnace followed by 20 min cooling in the open air. The thermogravimetric technique was used to establish the kinetics of Corrosion. The morphology, phase composition and element concentration of the Corrosion products were detected using the combined techniques of X-ray diffractometry (XRD), scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) and electron probe micro analyzer (EPMA). The Hot Corrosion resistance of NiCrBSi coating has been found to be better than that of Stellite-6 coating. The Hot Corrosion resistance of both the coatings has been attributed to the formation of oxides of chromium, silicon and nickel along with spinels of nickel–chromium and cobalt–chromium. These oxides seal/plug the pores and splat boundaries, and act as diffusion barriers to the inward diffusion of corroding species.
-
Hot Corrosion studies of hvof nicrbsi and stellite 6 coatings on a ni based superalloy in an actual industrial environment of a coal fired boiler
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Hot Corrosion of boiler tubes used for super-heaters and re-heaters in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. Attempts to decrease the maintenance costs of these components have increased interest in shielding them with protective coatings. The present investigation is an attempt to evaluate the Hot Corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed NiCrBSi and Stellite-6 coatings on a nickel-based superalloy in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 900 °C. Experiments were carried out for 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Both the coatings deposited on Ni-based superalloy imparted better Hot Corrosion resistance than the uncoated one. The Stellite-6 coated superalloy performed better than the NiCrBSi coated in the given environment.
-
Hot Corrosion studies of hvof nicrbsi and stellite 6 coatings on a ni based superalloy in an actual industrial environment of a coal fired boiler
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Hot Corrosion of boiler tubes used for super-heaters and re-heaters in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. Attempts to decrease the maintenance costs of these components have increased interest in shielding them with protective coatings. The present investigation is an attempt to evaluate the Hot Corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed NiCrBSi and Stellite-6 coatings on a nickel-based superalloy in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 900 °C. Experiments were carried out for 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Both the coatings deposited on Ni-based superalloy imparted better Hot Corrosion resistance than the uncoated one. The Stellite-6 coated superalloy performed better than the NiCrBSi coated in the given environment.
T S Sidhu - One of the best experts on this subject based on the ideXlab platform.
-
a comparative study of Hot Corrosion resistance of hvof sprayed nicrbsi and stellite 6 coated ni based superalloy at 900 c
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Abstract A comparative study was carried out to evaluate the Hot Corrosion resistance of NiCrBSi and Stellite-6 coated nickel-based superalloy Superni 600 (15.5Cr–10Fe–0.5Mn–0.2C–balance Ni) in the molten salt environment of Na 2 SO 4 –60%V 2 O 5 salt mixture at 900 °C under cyclic conditions. Hot Corrosion experiments were performed for 50 cycles, each cycle consisting of 1 h heating in the laboratory tube furnace followed by 20 min cooling in the open air. The thermogravimetric technique was used to establish the kinetics of Corrosion. The morphology, phase composition and element concentration of the Corrosion products were detected using the combined techniques of X-ray diffractometry (XRD), scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) and electron probe micro analyzer (EPMA). The Hot Corrosion resistance of NiCrBSi coating has been found to be better than that of Stellite-6 coating. The Hot Corrosion resistance of both the coatings has been attributed to the formation of oxides of chromium, silicon and nickel along with spinels of nickel–chromium and cobalt–chromium. These oxides seal/plug the pores and splat boundaries, and act as diffusion barriers to the inward diffusion of corroding species.
-
Hot Corrosion studies of hvof nicrbsi and stellite 6 coatings on a ni based superalloy in an actual industrial environment of a coal fired boiler
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Hot Corrosion of boiler tubes used for super-heaters and re-heaters in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. Attempts to decrease the maintenance costs of these components have increased interest in shielding them with protective coatings. The present investigation is an attempt to evaluate the Hot Corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed NiCrBSi and Stellite-6 coatings on a nickel-based superalloy in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 900 °C. Experiments were carried out for 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Both the coatings deposited on Ni-based superalloy imparted better Hot Corrosion resistance than the uncoated one. The Stellite-6 coated superalloy performed better than the NiCrBSi coated in the given environment.
-
Hot Corrosion studies of hvof nicrbsi and stellite 6 coatings on a ni based superalloy in an actual industrial environment of a coal fired boiler
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Hot Corrosion of boiler tubes used for super-heaters and re-heaters in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. Attempts to decrease the maintenance costs of these components have increased interest in shielding them with protective coatings. The present investigation is an attempt to evaluate the Hot Corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed NiCrBSi and Stellite-6 coatings on a nickel-based superalloy in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 900 °C. Experiments were carried out for 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Both the coatings deposited on Ni-based superalloy imparted better Hot Corrosion resistance than the uncoated one. The Stellite-6 coated superalloy performed better than the NiCrBSi coated in the given environment.
-
Hot Corrosion studies of hvof sprayed cr3c2 nicr and ni 20cr coatings on nickel based superalloy at 900 c
Surface & Coatings Technology, 2006Co-Authors: T S Sidhu, S Prakash, R D AgrawalAbstract:Abstract The high velocity oxy-fuel (HVOF) process is widely adopted by many industries due to its flexibility, cost effectiveness, handiness for use and the superior quality of the coatings produced. The present work is a comparative study of HVOF sprayed Cr3C2–NiCr and Ni–20Cr coatings on a Ni-based superalloy in a molten salt environment of Na2SO4–60%V2O5 at 900 °C under cyclic conditions. The thermogravimetric technique was used to establish the kinetics of Corrosion. X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe microanalysis techniques were used to analyse the Corrosion products. The Hot Corrosion resistance of Ni–20Cr coating was better than Cr3C2–NiCr coating. The Hot Corrosion resistance of both coatings may be attributed to the formation of oxides and spinels of nickel and chromium. These oxides might have blocked the pores and splat boundaries, and acted as diffusion barriers to the inward diffusion of oxidizing species.
-
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.
S.l. Mannan - One of the best experts on this subject based on the ideXlab platform.
-
Isothermal high temperature low cycle fatigue behavior of Nimonic-263: Influence of type I and type II Hot Corrosion
Materials Science and Engineering A, 2015Co-Authors: J K Sahu, N. Paulose, B. Ravi Kumar, S. K. Das, S.l. MannanAbstract:Accelerated oxidation and Corrosion of aero engine components due to the presence of Hot salt mixture in the operating condition is known as Hot Corrosion. Hot Corrosion degrades life of aero engine components and is broadly divided as type I and type II based on the prevailing temperature and type of salt present in the salt mixture and accordingly the mechanisms of degradation are different. Though type I and type II Hot Corrosion mechanisms are established but simultaneous interaction of cyclic load and Hot corrosive media on aero engine material is relatively unknown. The different micro-mechanisms of interaction of types I and II Hot-Corrosion and low-cycle fatigue is studied in the present investigation by conducting fatigue tests at 700, 800°C on bare and salt-coated specimens; studying specimen surface degradation and fracture surface through extensive microscopy. Type-I Hot Corrosion is induced at 800°C by depositing 90% Na2SO4+10% NaCl and type-II HC is induced at 700°C by depositing 88% Na2SO4+7% NaCl+5% NaVO3 on fatigue test specimens. Fatigue life is significantly reduced in both the Hot corrosive atmospheres; however, the operative mechanisms are significantly different. Type-I atmosphere leads to sporadic fluxing of protective Cr2O3 layer exposing the substrate to Hot corrosive media leading to grain-boundary oxidation and inter-granular failure whereas; type-II atmosphere leads to surface cracking and trans-granular failure.
-
influence of Hot Corrosion on low cycle fatigue behavior of nickel base superalloy su 263
International Journal of Fatigue, 2013Co-Authors: J K Sahu, N. Paulose, R K Gupta, J Swaminathan, S.l. MannanAbstract:Abstract The influence of Hot Corrosion on low cycle fatigue behavior is studied by conducting fatigue tests at 800 °C in air on bare and salt-coated (90%Na 2 SO 4 + 10%NaCl) specimens. This was followed by extensive scanning electron microscopic (SEM) examinations. Significant reduction in fatigue life is observed across all values of Δ e t /2 for the salt-coated specimens in comparison with bare specimens. SEM examination reveals that the fused salt mixture sporadically removes the protective chromium oxide layer and exposes the substrate. Subsequent SEM analysis reveals that severe grain boundary oxidation leads to grain boundary cracking and provides numerous sites for fatigue crack nucleation and growth.
Peng Song - One of the best experts on this subject based on the ideXlab platform.
-
influence of alloying elements on Hot Corrosion resistance of nickel based single crystal superalloys coated with na2so4 salt at 900 c
Materials & Design, 2021Co-Authors: Peng Song, Mingfeng Liu, Xiangwei Jiang, Yuchao Feng, Gong Zhang, Dong Wang, Jiasheng Dong, Xingqiu ChenAbstract:Abstract Hot Corrosion behavior of three nickel-based single crystal superalloys with different key alloying elements (including Re, Cr, Al and Ti) contents in molten Na2SO4 salt at 900 °C was investigated. Comparative study of Hot Corrosion resistance was conducted on two Re-free superalloys with 12 wt% Cr and different content of Al and Ti. By further adding Re, the experimental alloy with moderate Cr content (8.5 wt%) and Al/Ti > 1 in the present research also exhibited excellent Hot Corrosion resistance. The influence mechanism of Re on promoting Hot Corrosion resistance was attempted to be explored in combined with first-principle calculation. In addition, the potential design space of new-developed single crystal superalloys was also proposed.