Effect of La{sub 2}O{sub 3} particles on the oxidation of electrodeposited nickel films

Journal Article · Thu Apr 01 04:00:00 EST 1999 · Oxidation of Metals

DOI:https://doi.org/10.1023/A:1018874707526· OSTI ID:351481

Peng, X; Li, T; Wu, W ^[1]

---

1. Academia Sinica, Shenyang (China)

Electrodeposited Ni-La{sub 2}O{sub 3} composite films with nanometer-size La{sub 2}O{sub 3} oxide inclusions were fabricated by the codeposition of nickel with La{sub 2}O{sub 3} particles. The comparative oxidation behavior in air at 900 and 1000 C of nickel coated with the Ni-La{sub 2}O{sub 3} composite and films with and without nickel-plating was studied by TGA, AE, SEM/EDX, EPMA, and TEM/EDX. In general, the Ni-La{sub 2}O{sub 3} composite-coated nickel had the slowest rate and the best resistance to thermal cycling. AE tests revealed that cracking events in NiO scales on Ni-La{sub 2}O{sub 3} composite-coated nickel was significantly reduced in comparison to that of the scale on nickel-coated nickel during thermal cycling at 900 C. SEM investigation showed that the La{sub 2}O{sub 3}-free NiO scale was composed of outer coarse columnar grains and inner equiaxed ones. By contrast, the scale on the Ni-La{sub 2}O{sub 3} composite-coated nickel consisted of only fine equiaxed NiO grains. The scale on the La{sub 2}O{sub 3}-free samples was characterized by cracks that originated at the scale-substrate interface and spanned the scale thickness. By contrast, no scale cracks formed at the La{sub 2}O{sub 3}-doped NiO scale-substrate interface, but small voids were created at the triple points of the grain boundaries of NiO. In the La{sub 2}O{sub 3}-doped NiO scale, segregation of La ions to the NiO grain boundaries near the scale-surface was observed by EDX microanalyses in the TEM.

• OSTI ID: 351481
• Journal Information: Oxidation of Metals, Journal Name: Oxidation of Metals Journal Issue: 3-4 Vol. 51; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
CRACKS
ELECTRODEPOSITION
KINETICS
LANTHANUM OXIDES
NICKEL
OXIDATION
PARTICULATES
SCALING
TEMPERATURE RANGE 1000-4000 K