Comparison of microstructure and oxidation behavior between Pt-free and Pt-modified δ-Ni2Si coatings on Ni-based superalloys. (September 2015)

• Record Type: Journal Article
• Authors: Fu, C.; Wang, C.H.; Ren, Z.M.; Cao, G.H.
• Is Part Of: Corrosion science. Volume 98(2015)
• Page Start: 211
• Page End: 222
• Publication Date: 2015-09
• Subjects: A. Metal coatings -- A. Superalloys -- A. Platinum -- C. Oxidation -- C. Segregation; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2015.05.030
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Pt decreases the chemical activity of Al to promote Al uphill diffusion. Pt improves the oxidation resistance of the Pt-modified δ-Ni2 Si coatings. Al-rich layer is formed in the Pt-modified δ-Ni2 Si coatings. Al-depleted and Cr-rich layers are formed in the Pt-free δ-Ni2 Si coatings. Abstract: This study investigated the microstructure and oxidation behavior of Pt-free and Pt-modified δ-Ni2 Si coatings prepared by codeposition of Al and Si. The composition (in wt.%) of packs was 1Al–4NH4 Cl– x Si-(95 − x )Al2 O3 with different Si levels ( x = 4, 6, 8, 10). Pt promotes uphill diffusion of Al in Pt-modified coatings while Cr tends to outward diffuse into Pt-free coatings. The isothermal oxidation tests indicated the coating with 10 wt.% Si had good oxidation performance. After oxidation, the microstructure of Pt-modified coatings was Cr2 NiO4 + NiO or Cr2 NiO4 + NiO + Al2 O3 while that of Pt-free coatings was Cr2 O3 + Ni31 Si12 + Al2 O3 .