Effect of Aluminising on the Hot Corrosion Resistance of Nickel-Chromium Alloys

2006 ◽  
Vol 514-516 ◽  
pp. 505-509 ◽  
Author(s):  
César A.C. Sequeira ◽  
Fernand D.S. Marquis
Keyword(s):  
Corrosion Resistance ◽  
Molten Salt ◽  
Hot Corrosion ◽  
Xrd Analysis ◽  
Weight Percent ◽  
Test Results ◽  
Nickel Chromium ◽  
Chromium Alloys ◽  
Nial Phase ◽  
Cyclic Corrosion

The effects of aluminising on the hot corrosion resistance of two nickel-chromium alloys containing 10 and 30 weight percent chromium, respectively, were examined. The Ni/Cr specimens were aluminised by pack cementation in Ar and underwent cyclic hot corrosion testing in Na2SO4- NaCl molten salt. XRD analysis indicated that a NiAl phase formed between the coating layer and substrate. Cyclic hot corrosion test results indicated that the effects of aluminising are more pronounced in the case of the 10 % Cr than in the case of 30 % Cr. The ductile NiAl phase suppressed the potential for crack initiation during thermal cycling of the 10 % Cr specimens, and reinforced the hot cyclic corrosion resistance in molten salt for the 30 % Cr specimens.

scholarly journals Study of Molten Salt Corrosion of Superni-75 using Termogravimetric Technique

1970 ◽  
Vol 3 (2) ◽  
pp. 77-82 ◽  
Author(s):  
TS Sidhu ◽  
S Prakash ◽  
RD Agrawal
Keyword(s):  
Corrosion Resistance ◽  
Molten Salt ◽  
Hot Corrosion ◽  
Corrosion Behaviour ◽  
Thick Layer ◽  
X Ray Diffraction ◽  
Salt Corrosion ◽  
Marine Engineering ◽  
The Given ◽  
Kinetics Of

The present study aims to evaluate the hot corrosion behaviour of the Ni-based alloy Superni- 75 in the molten salt environment of Na2SO-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. Superni-75 has successfully provided the hot corrosion resistance to the given molten salt environment. The hot corrosion resistance of the Superni-75 has been attributed to the formation of uniform, homogeneous and adherent thick layer of the scale consisting mainly of oxides of nickel and chromium, and refractory Ni(VO3)2. These oxides and refractory nickel vanadates have blocked the penetration of oxygen and other corrosive species to the substrate. Keywords: Hot corrosion, nickel-based alloy, superalloy, molten salt environment   DOI: 10.3329/jname.v3i2.922 Journal of Naval Architecture and Marine Engineering 3(2006) 77-82

Hot Corrosion Studies on GTA Welded AISI 304, Monel 400 Subjected to Air Oxidation and Molten Salt Environment

2011 ◽  
Vol 383-390 ◽  
pp. 4688-4692
Author(s):  
Ramkumar K. Devendranath ◽  
N. Arivazhagan ◽  
S Narayanan
Keyword(s):  
Molten Salt ◽  
Hot Corrosion ◽  
Gta Welding ◽  
Xrd Analysis ◽  
Air Oxidation ◽  
Aisi 304 ◽  
Nickel Copper ◽  
Steel Aisi ◽  
Monel 400 ◽  
Marine Applications

An attempt was made to study the hot corrosion behavior on gas tungeten arc welded Austenitic stainless steel AISI 304 and Nickel-copper alloy Monel 400. These materials are widely used in power plant, petro-chemical and marine applications where the weldments are usually subjected to aggressive corrosion environment. GTA welding was carried out using ENiCu-7 and E308L filler wires. Various regions of the weldment of AISI 304, Monel 400 were exposed to the air oxidation as well as in the molten salt environment consist of K2SO4 + NaCl (60%) at 700°C. Mechanical properties of the weldments were also studied. The corrosion products of the weldments were analyzed using SEM/EDAX, XRD analysis.

Low-Pressure Plasma-Spray Coatings for Hot-Corrosion Resistance

1981 ◽  
Vol 103 (1) ◽  
pp. 146-153 ◽  
Author(s):  
R. W. Smith ◽  
W. F. Schilling ◽  
H. M. Fox
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Hot Corrosion ◽  
Low Pressure ◽  
Attractive Alternative ◽  
Test Results ◽  
Al2o3 Scale ◽  
Pressure Plasma ◽  
Low Pressure Plasma ◽  
Plasma Sprayed

The hot corrosion of low-pressure plasma-sprayed coating, GT-29 (Co-29Cr-6Al-1Y) on a γ′-strengthened nickel base superalloy, IN-738, was characterized at both 871 °C and 983 °C in a simulated gas turbine environment. The test results show that at 871 °C the dense, defect-free, low-pressure, plasma-sprayed GT-29 coatings provide good corrosion protection up to 8000 hr. The mechanism of protection was the formation of a dense, adherent Al2O3 scale underneath a mixed oxide scale; scale was maintained by a uniformly dispersed Al rich β(CoAl) reservoir. At 982 °C, the coating corrosion protection exceeded 5000 hours and also utilized a protective Al2O3 scale. Due to the higher test temperature, interdiffusion of O, S, Al, Co, and Cr was higher and internal sulfidation/oxidation of the coating occurred; however, the rates were much lower than uncoated IN-738. Field tests were run (13051 and 19842 hr) to evaluate the low-pressure, plasma-sprayed GT-29 coatings’ corrosion resistance on turbine buckets. Metallographic inspection of the field-tested coatings verified the simulated burner-rig test results and demonstrated that the low-pressure plasma process provides an attractive alternative to other coating processes for producing hot-corrosion resistant coatings.

Aluminizing and boroaluminizing treatments of Mar-M247 and their effect on hot corrosion resistance in Na2SO4−NaCl molten salt

2003 ◽  
Vol 9 (3) ◽  
pp. 303-310 ◽  
Author(s):  
J. H. Cho ◽  
T. W. Kim ◽  
K. S. Son ◽  
J. H. Yoon ◽  
H. S. Kim ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Molten Salt ◽  
Hot Corrosion

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.

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