The corrosion behavior of Ni-Mo alloys in a H sub 2 /H sub 2 O/H sub 2 S gas mixture

Journal Article · Mon Jun 01 00:00:00 EDT 1992 · Oxidation of Metals; (United States)

OSTI ID:7266950

Gesmundo, F ^[1]

---

1. Univ. di Genova (Italy)

The corrosion behavior of Ni-Mo alloys containing up to 40 wt.% Mo was studied over the temperature range of 550-800 C. in a mixed gas of H{sub 2}/H{sub 2}O/H{sub 2}S. The scales formed on all alloys contained only sulfides and were double-layered. The outer scale was single-phase Ni{sub 3}S{sub 2}. Depending on the alloy composition and reaction conditions, the inner scale was: (1) a mixture of MoS{sub 2}plus Ni{sub 3}S{sub 2} with/without Ni, (2) MoS{sub 2}, or (3) MoS{sub 2} plus intermediate particles and/or double sulfide Ni{sub 2.5}Mo{sub 6}S{sub 6.7}. Neither internal oxidation nor internal sulfidation were observed at lower temperatures. Internal sulfidation was however observed at higher temperature when the scale apparently melted. The parabolic law was generally obeyed for the most concentrated alloys. For the two more-dilute alloys the kinetics were mostly linear. A decrease in the corrosion rate occurred with increasing Mo content of the alloy and may be attributed to the presence of increasing volume fractions of MoS{sub 2} and/or of a double Ni-Mo sulfide in the inner region of the scale. For the two most concentrated alloys this may also be due to the presence of a number of particles of the unsulfidized intermetallic compound, which is Ni{sub 3}Mo for Ni-30Mo, but NiMo for Ni-40Mo.

• OSTI ID: 7266950
• Journal Information: Oxidation of Metals; (United States), Vol. 37:5-6; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
01 COAL, LIGNITE, AND PEAT
HYDROGEN
CORROSIVE EFFECTS
HYDROGEN SULFIDES
MOLYBDENUM ALLOYS
CORROSION
NICKEL BASE ALLOYS
WATER VAPOR
ACTIVATION ENERGY
CHEMICAL COMPOSITION
CHEMICAL REACTION KINETICS
COAL GASIFICATION
CORROSION PRODUCTS
EXPERIMENTAL DATA
INTERMETALLIC COMPOUNDS
LAYERS
MICROSTRUCTURE
MOLYBDENUM SULFIDES
NICKEL SULFIDES
PHASE DIAGRAMS
QUANTITY RATIO
SCANNING ELECTRON MICROSCOPY
STABILITY
SULFIDATION
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
WEIGHT
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DATA
DIAGRAMS
DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
ENERGY
FLUIDS
GASES
GASIFICATION
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
MICROSCOPY
MOLYBDENUM COMPOUNDS
NICKEL ALLOYS
NICKEL COMPOUNDS
NONMETALS
NUMERICAL DATA
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SCATTERING
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE RANGE
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
VAPORS
360105* - Metals & Alloys- Corrosion & Erosion
010404 - Coal
Lignite
& Peat- Gasification