Kinetics of formation and properties of a barrier oxide film on molybdenum

Photo-electrochemical investigation of anodic oxide films on cast Ti–Mo alloys. I. Anodic behaviour and effect of alloy composition

“…The presence of Mo into the passive layer has been ascertained in preliminary XPS experiments, to be discussed in a future work [15]. This result is expected considering that also pure Mo is reported to display a valve-metal behaviour in suitable solutions [22][23][24], as well as previous results regarding other barrier-type films on alloys [13,14,[25][26][27][28][29][30][31][32][33][34][35]. Moreover, it is in agreement with literature data on Ti-Mo alloys: Auger spectroscopy on very thin anodic films showed Mo peaks attributed to its ion state [36]; more recently, composition of much thicker films on Ti-Mo alloys richer in Mo (11.5-37 at.%) was analyzed by Rutherford backscattering and glow discharge optical emission spectroscopy [37,38]: a two-layered structure, with a thin external pure TiO 2 layer and an inner mixed Ti-Mo oxide was found for these films, amorphous in structure.…”

“…In fact, optical gap values reported in Table 3 are compatible with those of pure component oxides, as well as with the formation of a mixed TiO 2 -MoO 3 phase: E g values of 3.0, 3.2 and 3.35 eV are reported for rutile, anatase and amorphous TiO 2 phase, respectively [12,17,20,21,[52][53][54][55][56], whilst for MoO 3 band gaps equal to 2.9 (␣ phase), 3.1 (␤ phase) and 3.3 (a-MoO 3 ) eV can be assigned [12,24,[57][58][59]. Similarity in the gap values of the two oxides arises from almost coincident electronegativities of both metal cations [12,60].…”

Transpassivity characterization of the alloy UNS N08367 in a chloride-containing solution

“…Based on the hypothesis of selective dissolution of Fe through the passive film on Fe-Cr alloys, it is assumed that the dissolution of Cr as Cr(III) at the film-solution interface is negligible compared with the dissolution of Fe as Fe(III) [4]. According to the surface charge approach proposed by Bojinov and coworkers [4,14,[27][28][29][30][31], the passive film was represented as a doped ntype semiconductor-insulator-p-type semiconductor (n-i-p) structure with an injection of oxygen vacancies (donors) from the metal substrate during film growth and metal vacancies (acceptors) from the electrolyte during film dissolution. The cation vacancies accumulate at the film-solution interface if the transport rate of these vacancies is slower than the rate of their annihilation at the metal-film interface.…”

Potency of ZnFe2O4 Nanoparticles as Corrosion Inhibitor for Stainless Steel; the Pigment Extract Study

“…This result may be attributed to smaller particle size of α-NZF (see Figure 1) which can be adsorbed more easily compared to other nanoparticles on the mild steel surface. The application of these pigments leads to diminish the possible corrosive attack via formation of a protective film 43 . According to Table 2, R ct values after 44 h are about 798 (Blank), 3475 (α-NZF), 935 (β-NZF), and 1491 (γ-NZF) Ω.cm 2 .…”