Untitled

Xiang, Zheng; Burnell-Gray, J. S.; Datta, P.K.

doi:10.1023/a:1012534220165

Cited by 140 publications

(49 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Among the chloride salts studied [13], NH 4 Cl is one of the most effective activators. Indeed, decomposition of the activator at elevated temperature generates some H 2 , which promotes the depositing reaction at the substrate surface.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Gaseous corrosion of alloys and novel coatings in simulated environments for coal, waste and biomass boilers

Kalivodová¹,

Baxter²,

Schütze

et al. 2005

Materials and Corrosion

View full text Add to dashboard Cite

The reduction of emissions from power generation plants is a key part of the Kyoto Protocol. Reduced emissions per unit of power produced can be achieved via increased thermal efficiency and this can be achieved by increasing steam parameters (i.e. temperature and pressure). Increased steam parameters in turn leads to accelerated corrosion of boiler components. Biomass and solid waste fuels introduce a number of aggressive species into process environments that result in enhanced rates of boiler degradation. This paper reports on studies, both theoretical and experimental, of the corrosion behaviour of high-alloy steels and Ni-base alloys as well as coatings for use in high efficiency coal and/or biomassand waste-fired power plants. Coatings produced within the SUNASPO project have been laboratory tested in gaseous atmospheres representative of coal combustion, biomass combustion and waste incineration. Laboratory tests were carried out mainly in the temperature range 500 C to 800 C. Initial results showed the poor performance of traditional uncoated low-alloy boiler steels P91 (9% Cr) and HCM12A (12% Cr), as well as the higher alloy steel, 17Cr/13Ni. Results show the beneficial effects of coatings containing Al, Si, Al + Si, Al + Ti and Al + B in reducing the rate of corrosive attack. In a combustion product gas containing 100 ppm HCl and 1000 ppm SO 2 , aluminizing affords corrosion resistance of low-alloy steels such as HCM12A and P91 similar to that of Alloy 800 over 1000 h of test. The presence of Al inhibits internal, sometimes localized corrosion by promoting the formation of a protective surface oxide layer even at relatively low temperatures. The results of experiments in simulated coal; biomass and waste atmospheres are presented and discussed in terms of both corrosion kinetics and mechanisms of degradation.

show abstract

Section: Resultsmentioning

confidence: 99%

“…This was also the reason for using the Ar + 10% H 2 gas during the pack cementation process. Changing activators or coating temperatures may affect the coating growth rate, but not the coating formation process or coating structure [13].…”

Section: Resultsmentioning

confidence: 99%

Gaseous corrosion of alloys and novel coatings in simulated environments for coal, waste and biomass boilers

Kalivodová¹,

Baxter²,

Schütze

et al. 2005

Materials and Corrosion

View full text Add to dashboard Cite

show abstract

“…Examination under the optimal microscope revealed the presence of pack alumina particles in the top surface of the coating. This is a typical feature, suggesting that the coating was formed via an outward growth process involving Co enrichment and the outward migration of substrate elements, Cr and Fe in particular [11,15,16]. Further evidence supporting the suggestion of the outward growth process came from the XRD spectrum measured from the as-coated surface, which is shown in Fig.…”

Section: Coating Of Substratementioning

confidence: 62%

Evaluation of the Parabolic Rate Constant During Different Types of Oxidation Tests for Spinel Coated Fe–17%Cr Alloy

Ebrahimifar

Zandrahimi

2010

Oxid Met

View full text Add to dashboard Cite

Oxidation resistance, and the long-term stability of interconnects in solid oxide fuel cells, can be ameliorated by the use of a protective, effective, relatively dense and well adherent, spinel coating. In this study, the pack cementation method was employed to coat cobalt onto AISI 430 ferritic stainless steel. Isothermal oxidation, cyclic oxidation, and oxidation at different temperatures (600-900°C) were applied to evaluate the parabolic rate constant (k p ). In each test, the coated samples demonstrated lower k p, indicating that the coating layer was effective. The formation of MnCo 2 O 4 and CoCr 2 O 4 spinels, during the oxidation, improved the oxidation resistance of AISI 430 ferritic stainless steel.

show abstract

“…It is essentially an in situ chemical vapor deposition (CVD) coating process. 5) Four inter-processes, namely halide activation, gas diffusion, solid deposition, and solid diffusion reactions, take place in sequence to form solid coatings by gas-solid reactions. 6,7) The pack cementation process has the advantages of low cost and applicability to various materials shapes and sizes.…”

Section: Introductionmentioning

confidence: 99%

Formation of Al and Cr Dual Coatings by Pack Cementation on SNCM439 Steel

Chen

Huang

2012

ISIJ Int.

View full text Add to dashboard Cite

Two stage pack cementation processes are developed to form dual Fe-Al-Cr layers on surfaces of SNCM439 steels. The first 550°C treatment assists to modulate adequate aluminum activity for the formation of iron-rich intermetallics. In the second 750°C treatment stage, simultaneous chromizing and aluminizing treatments are achieved by first forming a FeAl ferritic layer and then a surface layer with higher Cr content at later time. The current study examines the effects of second stage 750°C holding time, activator concentration, and Cr:Al ratio on coating structures. Fe-Al coatings consisting of Fe3Al and FeAl intermetallic phases are observed to form initially. This Fe-Al layer accounts for 25 to 32 μ m thickness of the coatings and show good adherence with the substrates. The coating thickness increases parabolically with 750°C holding time. With prolonged treatment at 750°C, surface concentration of aluminum in powder packs drops with treatment time and increasing concentration of activator. A peak concentration exists at a depth below substrate surface. Aluminum is back diffused from the steel surface into the powder packs. The growth of Fe-Al intermetallics slows down. Surface layer then forms a thickness of 6 μ m coating with 2-5 wt.% of chromium. Samples treated for longer than 6 h with over 12 wt.% of NH4Cl activator concentration or with Cr:Al ratio higher than 90:10 induce earlier chromium infusion and lead to porous coating structure due to Kirkendall effect. Eventually chromium carbide forms to cease further growth of the dual coating structures.

show abstract

Untitled

Cited by 140 publications

References 2 publications

Gaseous corrosion of alloys and novel coatings in simulated environments for coal, waste and biomass boilers

Gaseous corrosion of alloys and novel coatings in simulated environments for coal, waste and biomass boilers

Evaluation of the Parabolic Rate Constant During Different Types of Oxidation Tests for Spinel Coated Fe–17%Cr Alloy

Formation of Al and Cr Dual Coatings by Pack Cementation on SNCM439 Steel

Contact Info

Product

Resources

About