High-temperature sulfidation behavior of Ni-Nb alloys

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Oxid. Met.; (United States)

DOI:https://doi.org/10.1007/BF00846688· OSTI ID:5738066

Chen, M F; Douglass, D L; Gesmundo, F

The sulfidation properties of Ni-Nb alloys containing additions of niobium up to 40 wt.% have been studied at P/sub s/sub 2// = 0.01 atm over the temperature range 550-700/degree/C. The sulfidation reactions followed the parabolic rate law; the sulfidation rates decreased with increasing amounts of niobium. An Arrhenius plot of the rate constants gave activation energies of 25.0 /plus minus/ 3.5 kcal/mole. The scales formed on Ni-Ng alloys were multilayered, generally consisting of an outer layer of nickel sulfide (NiS/sub 1+x/ and Ni/sub 3/S/sub 2/) and an inner complex layer of NiNb/sub 3/S/sub 6/ plus NbS/sub 2/. The position of the original metal surface was noted by platinum-wire marker experiments to be the interface between the inner and outer layers. The location of the marker indicates that the outer layer, generally greater in thickness than the inner layer, grew by outward diffusion of the nickel cations, and the inner layer formed probably by the inward diffusion of sulfur. Neither preferential sulfidation nor internal sulfidation was observed. The development of the scale structures from the transient stage to steady state was also studied.

• Research Organization: Univ. of California, Los Angeles (USA)
• OSTI ID: 5738066
• Journal Information: Oxid. Met.; (United States), Journal Name: Oxid. Met.; (United States) Vol. 31:3-4; ISSN OXMEA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
ARRHENIUS EQUATION
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COHERENT SCATTERING
CORROSION
CORROSION PRODUCTS
CORROSION RESISTANCE
CORROSIVE EFFECTS
CRYSTAL STRUCTURE
DIFFRACTION
DIFFUSION
ELECTRON MICROPROBE ANALYSIS
ELECTRON MICROSCOPY
ELEMENTS
EQUATIONS
KINETICS
METALLURGICAL EFFECTS
METALS
MICROANALYSIS
MICROSCOPY
MICROSTRUCTURE
NICKEL
NICKEL ALLOYS
NICKEL BASE ALLOYS
NICKEL COMPOUNDS
NICKEL SULFIDES
NIOBIUM
NIOBIUM ALLOYS
NIOBIUM COMPOUNDS
NIOBIUM SULFIDES
NONMETALS
OPTICAL MICROSCOPY
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SCALING
SCANNING ELECTRON MICROSCOPY
SCATTERING
SULFIDATION
SULFIDES
SULFUR
SULFUR COMPOUNDS
TEMPERATURE EFFECTS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
X-RAY DIFFRACTION