ISSN:
1573-4889
Keywords:
oxidation
;
sulfidation
;
oxides
;
sulfides
;
Ti
;
Ti-6Al-4V alloy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Pure titanium and Ti-6Al-4V were exposed at 750°C in an H2/H2O/H2S PO 2≈10−18 Pa and PS 2≈10−1 Pa), H2/H2O (PO 2≈10−18 Pa) and air environments for up to 240 hr. The corrosion kinetics, obtained by the discontinuous gravimetric method, showed that the sulfidation/oxidation kinetics were linear for Ti and linear-parabolic for Ti-6Al-4V in the H2/H2O/H2S environment. Both materials obeyed parabolic rate laws in the H2/H2O atmosphere after a transient period, and linear-parabolic rate laws in air. After exposure to the H2/H2O/H2S atmosphere, the titanium specimen displayed a double scale of TiO2 with an intervening TiS2 film between the double-layered scale of TiO2 and the substrate. Ti-6Al-4V also contained a double layer of TiO2 together with a stratum consisting of Al2S3, TiS2 and vanadium sulfide at the junction of the inner TiO2 layer and substrate. Some Al2O3 precipitated in the external portion of the outer TiO2 layer. Following oxidation in the low-PO 2 atmosphere a double-layered oxide of TiO2 scale formed on both Ti and Ti-6Al-4V. The scale on Ti-6Al-4V also contained an α-Al2O3 film situated between the outer and inner (TiO2) layers. For both materials, multilayered-scale formation characterized air oxidation. In detail a multilayered oxide scale of TiO2 formed on the air-oxidized Ti, while a multilayered oxide scale with alternating layers of Al2O3/TiO2 developed on Ti-6Al-4V oxidized in air.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01046849
