scholarly journals Hot Corrosion Behaviour of Detonation Gun Sprayed Al2O3-40TiO2 Coating on Nickel Based Superalloys at 900°C

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
N. K. Mishra ◽  
Naveen Kumar ◽  
S. B. Mishra
Keyword(s):  
Elevated Temperature ◽  
Hot Corrosion ◽  
Elevated Temperatures ◽  
Corrosion Behaviour ◽  
Degradation Mechanism ◽  
Total Duration ◽  
Wide Range ◽  
Detonation Gun ◽  
Mechanism Of Failure ◽  
Corrosion Resistant Coatings

Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. These failures occur because of the usage of wide range of fuels such as, coal and oil at the elevated temperatures. Nickel based superalloys having excellent mechanical strength and creep resistance at elevated temperature are used under such environment but they lack resistance to hot corrosion at high temperature. To overcome these problems hot corrosion resistant coatings are deposited on these materials. In the current investigation Al2O3-40%TiO2 powder has been deposited on Superni 718 and AE 435 superalloys by Detonation Gun method. The hot corrosion performance of Al2O3-40%TiO2 coated as well as uncoated Superni 718 and AE 435 alloys has been evaluated in aggressive environment Na2SO4-82%Fe2(SO4)3 under cyclic conditions at an elevated temperature of 900°C. The kinetics of the corrosion is approximated by weight change measurements made after each cycle for total duration of 50 cycles. Scanning electron microscopy was used to characterize the hot corrosion products. The coated samples imparted better hot corrosion resistance than the uncoated ones. The AE 435 superalloy performed better than Superni 718 for hot corrosion in a given environment.

scholarly journals Hot Corrosion Behaviour of Detonation Gun Sprayed Stellite-6 and Stellite-21 Coating on Boiler Steel SAE 431 at 900°C

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
N. K. Mishra ◽  
A. K. Rai ◽  
S. B. Mishra ◽  
R. Kumar
Keyword(s):  
Hot Corrosion ◽  
Gas Turbines ◽  
Elevated Temperatures ◽  
Protective Coatings ◽  
Total Duration ◽  
Boiler Steel ◽  
Stellite 6 ◽  
Stellite 21 ◽  
Wide Range ◽  
Detonation Gun

Hot corrosion is the serious problem in gas turbines, superheaters, and economizers of coal-fired boilers. It occurs due to the usage of wide range of fuels such as coal, oil, and so on at the elevated temperatures. Protective coatings on boiler steels are used under such environments. In the present investigation, Stellite-6 and Stellite-21 coatings have been deposited on boiler steel SAE 431 by detonation gun method. The hot corrosion performance of Stellite-6 and Stellite-21 coated as well as uncoated SAE 431 steel has been evaluated in aggressive environment of Na2SO4-82%Fe2(SO4)3under cyclic conditions at an elevated temperature of 900°C for total duration of 50 cycles. Thermogravimetric technique was used to approximate the kinetics of hot corrosion. Stellite-6 coating imparted better hot corrosion resistance than Stellite-21 coating in the given environment. Scanning electron microscopy was used to characterize the surface of hot corrosion products.

Dynamic Behavior of Metals Under Tensile Impact—Part 1: Elevated Temperature Tests

1970 ◽  
Vol 37 (3) ◽  
pp. 765-770 ◽  
Author(s):  
A. B. Schultz
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Dynamic Behavior ◽  
Dynamic Loading ◽  
Elevated Temperatures ◽  
Uniaxial Tensile ◽  
Tensile Impact ◽  
Wide Range

The mechanical behavior of metals subjected to uniaxial tensile impact at elevated temperatures is reported. Tests were conducted on annealed 1100 aluminum at 200, 350, 550, and 800 deg F; annealed 2024 aluminum at 200, 450, and 600 deg; and annealed C1010 steel at 430, 700, 1050, and 1400 deg F. The materials exhibit a wide range of dynamic behavior, including some in which the stress required to produce a given level of strain is significantly lowered by dynamic loading. The ratios of the dynamic ultimate stresses to the static are found to range from 0.71–6.0.

Hot corrosion behaviour of Super 304H for marine applications at elevated temperatures

2017 ◽  
Vol 64 (5) ◽  
pp. 508-514 ◽  
Author(s):  
M. Adam Khan ◽  
S. Sundarrajan ◽  
S. Natarajan
Keyword(s):  
Hot Corrosion ◽  
Elevated Temperatures ◽  
Corrosion Behaviour ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Salt Mixture ◽  
Content Type ◽  
X Ray ◽  
Different Temperatures ◽  
Marine Applications

Purpose The aim of this paper is to study the hot corrosion behaviour of super 304H stainless steel for marine applications. Design/methodology/approach The investigation was carried out with three different combinations of salt mixture (Na2SO4, NaCl and V2O5) at two different temperatures (800 and 900°C). Findings The spalling and growth of oxide layer was observed more with the presence of V2O5 in the salt mixture at 900°C during experimentation than what was observed in 800°C. The mass change per unit area is calculated to study the corrosion kinetics and also the influence of salt mixture. Further, the samples are analysed through materials characterisation techniques using optical image, scanning electron microscope (SEM), energy dispersive X-ray (EDAX) and X-ray diffraction (XRD) analysis. The presence of V2O5 in the salt mixture was the most important influencing species for accelerating hot corrosion. Originality/value SEM, EDAX and XRD analysis confirmed the formation of Fe2O3 and Cr2O3 at 900°C showing contribution in corrosion protection.

Influence of Mineral Admixtures on Fracture Energy of Refractory Cement at Elevated Temperatures

2016 ◽  
Vol 866 ◽  
pp. 88-93
Author(s):  
B. Geethakumari ◽  
R. Ramesh Kumar ◽  
V. Syam Prakash
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Fracture Energy ◽  
Silica Fume ◽  
Elevated Temperatures ◽  
Rice Husk Ash ◽  
Mineral Admixtures ◽  
Three Point Bending ◽  
Wide Range ◽  
Refractory Cement

The influence of three mineral admixtures, Silica Fume (SF), Fly Ash (FA), and Rice Husk Ash (RHA) on the fracture energy of Refractory Cement (RC) over a wide range of temperature from 300K to 1173K is studied. The optimum percentage replacement of RC by these admixtures is found to be around 0.5 for all the temperatures considered but for FA. Fracture energy of control (0% admixture) and blended RC (with 0.5% admixture) are determined by three point bending of notched beam specimens. Fracture energy of RC blended with the three mineral admixtures is lower than that of control RC for temperature range of 300K to 873K. But at elevated temperature of 1173K, blending plays its role as an admixture. Experimental results are corroborating with XRD. It is observed that phenomenon of pseudo dryness of Gismondine in the blended RC causes higher fracture energy which is double that of RC only at 1173K.

scholarly journals HOT CORROSION BEHAVIOUR OF NICKEL BASED SUPERALLOYS

2013 ◽  
pp. 223-227
Author(s):  
K. SRINIVASA VADAYAR ◽  
S. DEVAKI RANI
Keyword(s):  
High Temperature ◽  
Surface Morphology ◽  
Hot Corrosion ◽  
Corrosion Behaviour ◽  
Degradation Mechanism ◽  
Sem Analysis ◽  
High Temperature Corrosion ◽  
Corrosive Environment ◽  
Weight Changes ◽  
Electron Dispersive Spectroscopy

High temperature corrosion of coated and uncoated IN738LC and uncoated CM247LC nickel based super alloys in chloride and vanadium environment were carried out. To create corrosive environment (i.e. chloride and vanadium environment) salts of required proportions of Na2SO4, NaCl and V2O5 were applied on both sides of samples and loaded into the furnace at 700°C and 900°C. The weight changes were noted and SEM analysis was done to determine the surface morphology of hot corroded samples. Electron Dispersive Spectroscopy (EDS) was used to determine different elements present in corroded samples of CM247LC and IN738LC in chloride and vanadium environments at 700°C and 900°C. The present study revealed that CM247LC is more susceptible to hot corrosion than IN738LC due to varying amount of chromium and tungsten which is explained by degradation mechanism. Coated IN738LC has more life span than that of other samples.

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