Evolution of oxide scale on a Ni-Mo-Cr alloy at 900 deg. C
- Materials Characterization Laboratory, Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, P. O. Box 1073, Dhahran 31261 (Saudi Arabia)
The cyclic oxidation behavior of a Ni-Mo-Cr alloy was studied in air at 900 deg. C for exposure periods of up to 1000 h. The morphology, microstructure and composition of the oxide scale was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Oxidation kinetics was determined by weight gain measurements. The results show that steady state oxidation was achieved within 1 h of exposure. During transient oxidation, the alloy grain boundaries intersecting the alloy surface became depleted in Ni and enriched in Mo and Cr. The scale initially formed at the surface was NiO which grew outwardly. However, a protective Cr{sub 2}O{sub 3} layer developed, rapidly retarding the rate of oxidation. Formation of NiMoO{sub 4} was also observed. The presence of Mo in the alloy facilitated the formation of a Cr{sub 2}O{sub 3} layer at an early stage of oxidation. The alloy exhibited considerable oxide spalling during prolonged exposure.
- OSTI ID:
- 21003520
- Journal Information:
- Materials Characterization, Vol. 58, Issue 1; Other Information: DOI: 10.1016/j.matchar.2006.03.005; PII: S1044-5803(06)00085-4; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
- Country of Publication:
- United States
- Language:
- English
Similar Records
Oxidation and reduction of Ni--Cr alloys
Corrosion behavior of Cr/sub 2/O/sub 3/--former alloys in H/sub 2/-H/sub 2/S-H/sub 2/O atmospheres