Formation of aluminide coatings on nickel by a fluidised bed CVD process

Voudouris, N.; Christoglou, Ch.; Angelopoulos, G.N.

doi:10.1016/s0257-8972(01)01193-8

Cited by 70 publications

(42 citation statements)

References 11 publications

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“…Phase transformation and growth may occur by both inward Al and outward Ni diffusion and finally by dominant Ni diffusion through the coating. 22,30 The Cr-rich zone (Fig. 6a,b) with low Al content was formed during the second-stage of the treatment and Cr content in the diffusion zone decrease in the same time, probably diluted in the thickening coating.…”

Section: Heat Treatmentmentioning

confidence: 99%

High-Temperature Oxidation of an Aluminized NiCr Alloy formed by a Magnetron-Sputtered Al Diffusion Coating

Brossard¹,

Balmain²,

Sanchette

et al. 2005

Oxid Met

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Aluminium diffusion coatings were obtained on Ni-20Cr substrate by sputtering an aluminium film, followed by a two stage diffusion treatment in an argon inert gas atmosphere (first stage at 600 • C, second at 900 or 1100 • C). Aluminides obtained at 900 • C and 1100 • C are close to those obtained by pack cementation process with high aluminium activity. These diffusion coatings are able to develop alumina scales during isothermal oxidation at high temperatures, whereas the untreated substrate had a chromia-forming behaviour. The weight gain recorded at 1100 • C on coated sample is then smaller than the one of uncoated NiCr at 950 • C. Presence of chromium was detected in the diffusion coating and Cr-rich precipitates were observed at the diffusion coating/substrate interface. After oxidation at 900 • C and 1100 • C, only α-Al 2 O 3 was revealed by XRD. An intermediate scale with a "whiskered" morphology could however be observed after 48 hr oxidation at 900 • C. After 100 hr of oxidation at 1100 • C, the Ni x Al y diffusion phases were no longer detectable and the upper part of the oxide scale spalled away during cooling. Large cavities appeared at the initial location of the diffusion coating/substrate interface.

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Section: Heat Treatmentmentioning

confidence: 99%

High-Temperature Oxidation of an Aluminized NiCr Alloy formed by a Magnetron-Sputtered Al Diffusion Coating

Brossard¹,

Balmain²,

Sanchette

et al. 2005

Oxid Met

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“…Reaction (5) is the source of HCl in the CVD reactor, which can be minimized if good vacuum is maintained. Some researchers consider the reduction of the monochloride of aluminum with hydrogen as a possible mechanism of deposition [21]. However, thermodynamic calculation showed that it would not have any significant contribution due to the unfavorable free energy.…”

Section: This Workmentioning

confidence: 99%

A kinetic model for iron aluminide coating by low pressure chemical vapor deposition: Part II. Model formulation

et al. 2004

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“…CVD and pack cementation are frequently used. Therefore, the chemical vapour deposition in fluidized bed reactor (CVD-FBR) is an important alternative for the deposition of Al coating on ferritic steels, because diffusion coatings can be obtained at relatively low temperatures (T \ 700°C) and short time [27][28][29][30][31][32][33]. These conditions allow the conservation of microstructure and mechanical properties of these types of steels.…”

Section: Introductionmentioning

confidence: 99%

Study of Oxyhydroxides Formation on P91 Ferritic Steel and CVD-FBR Coated by Al in Contact with Ar + 40% H2O at 650 °C by TG-Mass Spectrometry

2010

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The oxidation behaviour of P91 steel with and without Al-CVD-FBR coating was investigated by means of mass spectrometry and TG measurements. All samples were oxidized at 650°C for 190 h in an atmosphere of Ar ? 40%H 2 O. TG-MS experiments were conducted in a closed steam loop in order to obtain information about the oxyhydroxides formation as reaction between coatings and steam. During the oxidation of Al-CVD-FBR/P91 sample were detected volatile species as, FeO(g), Al 2 O 2 (g) around 25 h of test. AlOOH(g) and FeOOH(g) species around 100 h. FeOOH(g), Fe(OH) 3 (g) species around 125 h. FeOOH(g), Fe 2 O 3-H 2 O(g) species around 150 h. CrO 2 (g), volatile species around 175 h. Finally, Al(OH) 2 (g), Al(OH) 3 (g), Fe(OH) 3 (g) volatile species around 190 h. From those results the role of the coating element could be established and optimized for the coating durability. The morphology/composition and structure of oxidized samples were also studied using the SEM-back scattered electron images/EDS and XRD techniques.

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Formation of aluminide coatings on nickel by a fluidised bed CVD process

Cited by 70 publications

References 11 publications

High-Temperature Oxidation of an Aluminized NiCr Alloy formed by a Magnetron-Sputtered Al Diffusion Coating

High-Temperature Oxidation of an Aluminized NiCr Alloy formed by a Magnetron-Sputtered Al Diffusion Coating

A kinetic model for iron aluminide coating by low pressure chemical vapor deposition: Part II. Model formulation

Study of Oxyhydroxides Formation on P91 Ferritic Steel and CVD-FBR Coated by Al in Contact with Ar + 40% H2O at 650 °C by TG-Mass Spectrometry

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