The influence of silicon on the high-temperature oxidation of nickel

Influence of Silicon and Silicon/Sulfur-Containing Additives on Coke Formation during Steam Cracking of Hydrocarbons

“…Generally, at least 20 wt % Cr is required to ensure the formation of a Cr 2 O 3 layer during oxidation. , Before being exposed to the process stream, preoxidation of an alloy is carried out to form a protective oxide layer on the alloy surface. The composition and the structure of the oxide layer depend mainly on the bulk composition, on the type and amount of the minor alloy elements, and on the oxidation conditions . For heat-resistant alloys containing Fe, Cr, and Ni, formation of a Cr 2 O 3 layer during preoxidation is preferred due to its good stability …”

“…54,55 Si is found in the form of SiO 2 , which can be a continuous or discontinuous layer beneath Cr 2 O 3 . 50 Although the structure of the oxide layer is not analyzed in detail this study, based on the composition of the oxide layer as determined using EDX, it is believed that the Si applied by the pretreatment method has been covered by an oxide layer consisting of mainly MnCr 2 O 4 and Cr 2 O 3 during the preoxidation procedure. Accordingly, the suppressing effect of the oxidized Si-pretreated Incoloy 800HT on the coke formation in the stream cracking of hexane can then be attributed to the modification of the composition and the structure of the oxide layer and to a decreased diffusion of metals into the coke layer during cracking.…”

“…The composition and the structure of the oxide layer depend mainly on the bulk composition, on the type and amount of the minor alloy elements, and on the oxidation conditions. 50 For heatresistant alloys containing Fe, Cr, and Ni, formation of a Cr 2 O 3 layer during preoxidation is preferred due to its good stability. 49 Si is believed to facilitate the formation of a Cr 2 O 3 layer and to improve the resistance to oxidation.…”

“…For Fe-Ni-Cr alloys containing a minimal amount of Mn and Si, the oxide layer formed during oxidation generally has a layered structure with MnCr 2 O 4 on top of Cr 2 O 3 54,55. Si is found in the form of SiO 2 , which can be a continuous or discontinuous layer beneath Cr 2 O 3 50. Although the structure of the oxide layer is not analyzed in detail this study, based on the composition of the oxide layer as determined using EDX, it is believed that the Si applied by the pretreatment method has been covered by an oxide layer consisting of mainly MnCr 2 O 4 and Cr 2 O 3 during the preoxidation procedure.…”

Corrosion Resistance of a High-Silicon Alloy in Metal-Dusting Environments

“…The beneficial and detrimental effects of silica in the high-temperature oxidation of 20Cr/25Ni/Nb stainless steel have been investigated at temperatures up to 1,200°C in CO 2 environment [7]. The kinetics of oxidation leading to the formation of an amorphous SiO 2 layer on Ni-Si alloys containing up to 7 wt.% Si have been studied at temperatures ranging from 600 to 1,000°C in oxygen [8,9]. The Ni30Co-28Cr-2.8Si alloy (HAYNES Ò HR-160 TM ) has been shown to provide excellent resistance to sulfidation and chloride attack up to 1,000°C [10].…”