Thermochemical studies on hot ash corrosion of stainless steel 304 and inhibition by magnesium sulphate

Barbooti, Mahmood M.; Al-Madfai, Suham; Nassouri, Huda J.

doi:10.1016/0040-6031(88)87248-4

Cited by 25 publications

(7 citation statements)

References 6 publications

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“…Sundararajan et al [10] have also advocated the need for applying thermal spray coatings on the boiler components. Sodium vanadyl vanadate (Na 2 OÁV 2 O 4 Á5V 2 O 5 ), which melts at a relatively low temperature of 550 8C is found to be the most common salt deposit on boiler superheaters [11], however, little information is available on the high-temperature oxidation behaviour of Ni 3 Al coatings in such aggressive environments. That is why it has been decided to study the role of this coating to resist hot corrosion induced by molten salt environment consisting of Na 2 SO 4 -60%V 2 O 5 , which has a much lower melting point (%500 8C) than other compositions of Na 2 SO 4 -V 2 O 5 mixtures.…”

Section: Introductionmentioning

confidence: 99%

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Singh¹,

Puri²,

Prakash³

et al. 2007

Materials & Corrosion

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Ni 3 Al metallic powder was prepared by the mechanical mixing of pure nickel and aluminium powders and deposited on a Ni-base superalloy namely Superni 75 by the shrouded plasma spray process. Hot corrosion behaviour of Ni 3 Al coated and uncoated superalloy specimens was evaluated in a simulated environment of fossil fuel boilers comprising of Na 2 SO 4 -60%V 2 O 5 by accelerated corrosion tests. The accelerated testing was done under cyclic conditions for 50 cycles, with each cycle consisting of 1 h heating in the silicon carbide furnace and cooling for 20 min in air. The coated superalloy was also subjected to air oxidation for 50 cycles to get an idea about its oxidation behaviour and adherence of the Ni 3 Al coating and its oxide scale with the substrate superalloy. The oxide scales were characterised by X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray (SEM/ EDAX) analyses and electron probe microanalysis (EPMA). The uncoated superalloy suffered an accelerated corrosion in the form of spallation of its oxide scale, whereas the oxide scale formed on the Ni 3 Al coated specimen was intact during the air as well as the molten salt oxidation. Furthermore, the coating was found successful in preventing the internal oxidation of the substrate superalloy. The coating maintained its adherence to the substrate superalloy during the exposure to both the environments of the study. The XRD analysis revealed the presence of oxides like Al 2 O 3 , NiO and NiAl 2 O 4 in the oxide scale of the coated superalloy. The XRD results were further supported by the SEM/EDAX and EPMA analyses.

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Section: Introductionmentioning

confidence: 99%

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Singh¹,

Puri²,

Prakash³

et al. 2007

Materials & Corrosion

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“…4860) and aluminum finep owder with minimum assay99.7 pct (Art. 880), suppliedbyLoba Chemical( India), mixed in stoichiometric ratio 3:1 in the laboratory ball mill for 8h ours to form au niform mixture constitute the powder mixture for Ni 3 used as the powder carrying and shielding gas, and all the process parameters given in Table II were kept constant throughoutt he coating process.…”

Section: A Fo Rmulation Of Coatingsmentioning

confidence: 99%

“…Abovethe melting point, this ash material corrodes metalsb yl ong-term contact. [3] If the temperature of the metal surface is abovethe melting point of the salt'se utectic composition, very corrosive conditions develop with the moltensalts fluxing the protective oxide scales or directly dissolving the metal. [4] When considering coal-gasification processes, hot corrosion is expected to be ap roblem because the gas environment generally has large sulfur activitiesa nd lowo xygen activities and alsoc ontains substantiala mounts of salt.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

Sidhu

Prakash

2006

Metall Mater Trans A

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Nickel-and cobalt-based coatings were formulated by ashrouded plasma spray process on boiler tube steels, namely,ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11),and ASTM-SA213-T-22 (T22). The Ni-22Cr-10Al-1Y alloy powderw as sprayed as ab ond in each case before the final coating.The degradation behavior of the baredand coated steels was studied in the platen superheater of the coal-fired boiler.T he samples werei nserted through the soot blower dummy points with the help of stainless steel wires.T he coatingsw ere found to be effective in increasing resistancet o degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

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“…The most common deposit found on boiler super-heaters is the sodium vanadyl vanadate, Na 2 OÁV 2 O 4 Á5V 2 O 5 , which melts at a relatively low temperature (550°C). Above the melting point, this ash material corrodes metals by long-term contact [3]. One of the protective means to counteract the problem of high-temperature degradation is to coat the base material with a protective layer using various surface treatment techniques.…”

Section: Introductionmentioning

confidence: 99%

Comparative High Temperature Analysis of HVOF-Sprayed and Detonation Gun Sprayed Ni–20Cr Coating in Laboratory and Actual Boiler Environments

Kaushal¹,

Singh

Prakash

2011

Oxid Met

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High-velocity-oxy-fuel (HVOF) spray and detonation-gun (D-gun) spray techniques were used to deposit Ni-20Cr coatings on a commonly used boiler steel ASTM-SAE 213-T22. The specimens, with and without coating, were subjected to molten salt (Na 2 SO 4 -60%V 2 O 5 ) deposition in a laboratory furnace at 900°C to determine hot-corrosion resistance. Specimens were also exposed to the superheater zone of a thermal power plant boiler at an average temperature of 700°C under cyclic conditions to ascertain their erosion-corrosion (E-C) behavior. Mass-change measurements were taken to approximate the kinetics of corrosion and erosion-corrosion. In the case of E-C, the thickness lost data were also taken at the end of the exposure. The exposed specimens were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy/energy dispersive spectroscopy (FE-SEM/EDS). The HVOF-sprayed coating was found to be intact during exposure to both given environments; whereas the D-gun coating showed spallation of its oxide scale during exposure to the molten salt environments. An overall analysis of the results indicated that the HVOF-sprayed Ni-20Cr coating should be a better choice for the given boiler applications.

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Thermochemical studies on hot ash corrosion of stainless steel 304 and inhibition by magnesium sulphate

Cited by 25 publications

References 6 publications

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

Comparative High Temperature Analysis of HVOF-Sprayed and Detonation Gun Sprayed Ni–20Cr Coating in Laboratory and Actual Boiler Environments

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Thermochemical studies on hot ash corrosion of stainless steel 304 and inhibition by magnesium sulphate

Cited by 25 publications

References 6 publications

Hot corrosion of a plasma sprayed Ni3Al coating on a Ni‐base superalloy

Hot corrosion of a plasma sprayed Ni3Al coating on a Ni‐base superalloy

Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

Comparative High Temperature Analysis of HVOF-Sprayed and Detonation Gun Sprayed Ni–20Cr Coating in Laboratory and Actual Boiler Environments

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Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy

Hot corrosion of a plasma sprayed Ni₃Al coating on a Ni‐base superalloy