A novel method to promote selective oxidation of Ni-Cr alloys: Surface spreading α-Al2O3 nanoparticles. (September 2021)

• Record Type: Journal Article
• Authors: Xie, Yun; Huang, Yuanchao; Li, Yihang; Peng, Xiao
• Is Part Of: Corrosion science. Volume 190(2021)
• Publication Date: 2021-09
• Subjects: A. Alloy -- B. SEM, XRD -- C. Selective oxidation; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2021.109717
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: The bare Ni-10Cr alloy had insufficient Cr to form an external chromia scale in air at 800 °C. The α-Al2 O3 coated Ni-10Cr alloy succeeded in external chromia formation. The α-Al2 O3 nanoparticles assisted nucleation and growth of Cr2 O3, as they share the similar hcp crystal structure. Abstract: Following Wagner's classical oxidation theory, we suppose that a Ni-Cr alloy with the Cr concentration below the critical N Cr 1 (0.24) required for external Cr2 O3 scale formation but above the critical N Cr ( 2 ) (0.1) required for its steady-state growth, would be converted from a NiO former to a Cr2 O3 former, if the selective Cr oxidation of the binary alloy can be catalyzed at the beginning of oxidation. As is expected, spreading α-Al2 O3 nanoparticles on the surface of Ni-10Cr (NCr = 0.11) does cause it to become a Cr2 O3 former during oxidation at 800 °C. The α-Al2 O3 effect on oxidation is interpreted.