Anodic passivation of Type 316L stainless steel in a borate‐boric acid buffer solution was studied using cyclic voltammetry and Auger spectroscopy. Based on a comparison with the results obtained on the metals (iron, chromium, and nickel), the reduction peaks appearing in the voltammograms for the steel were attributed to the reductive dissolution of a ferric oxide and to valence transitions associated with chromium and nickel in the oxide. It is shown that cyclic voltammetry in the buffer solution provides a qualitative and semiquantitative analysis of the passive film growth. Okamoto's model of formation of two types of films, determined by the anodization potential, is found to be applicable; the mechanism of oxide growth is related to selective enrichment of iron or chromium, which is based on solubility relationships predicted by thermodynamic considerations.

The slow dehydration and dehydroxylation of porous Vycor glass was followed by infrared spectroscopic techniques. Two sharp bands at 3748 and 3703 cm-1 and also two shoulders near 3850 and 3650 cm-1 were observed. Dehydroxylation, deuteration, fluoridation, and adsorption experiments showed all absorptions to be due to surface hydroxyl species. The 3748-cm-1 absorption is due to free surface silanol groups. The 3650-cm-1 shoulder is due to OH vibrations perturbed by hydrogen bonding. The 3703-cm-1 band has a half-width of 5 to 14 cm-1 and can only be observed at relatively low surface coverage. Impregnation of silica and porous glass with boric acid produced a band at 3703 cm-1 with the silica and enhanced that found with the glass, leading to the assignment of the 3703-cm-1 band to a B-OH surface structure. The nature of the species responsible for the 3850-cm-1 shoulder is uncertain.CaF2 optics, mention the formation of a 30-cm-1 spaced doublet when porous glass was evacuated for 1 hr at 900°. They state that the nature of the second,(1) T.

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Infrared spectra of NH3 sorbed on highly dehydroxylated, deuterated, and fluoridated porous glass were recorded. Two pairs of bands at 3409 and 3320 cm-1 and at 3330 and 3308 cm-1 were attributed to physically adsorbed NH3, hydrogen bonded to the SiOH and BOH groups of the glass surface, respectively. Bands at 3368 and 3282 cm-1 were ascribed to a =B-NH3 complex. Two pairs of bands at 3569 and 3479 cm-1 and at 3543 and 3459 cm-1 were ascribed to =BNH2 and =SiNH2 groups, respectively. A single band at 3455 cm-1 was tentatively assigned to the N-H stretching vibration of a secondary amine, the nitrogen atom being bonded to two surface boron atoms.There have been numerous reports dealing with the sorption of NH3 on porous glass.1-15 A variety of experimental techniques has been used and there seems to be a general agreement about the role of surface silanol groups as sites for a weakly bonded NH3 adsorption. A strong adsorption requiring sites other than silanols has also been reported. Folman and Yates suggested that the strong sites were silicon or oxygen atoms.1 2345However, Cant and Little pointed out that porous glass contained 3% B203 and stated that it was not impossible that strongly bound NH3 was adsorbed on electron-deficient surface boron atoms themselves.12 Chapman and Hair similarly concluded that strong NH3 adsorption occurred on (1) D.

o extinction coefficient of azomethane is small,7 we may write 70 = 7?n/[A], Plots of µ and vs. 7?n/[A] are shown in Figure 3, and the expected independence of the quantum yields with respect to pressure and intensity is evident at low intensities. The values of ho/h and ß at 180°are 1.0 ± 0.1 and (1.1 ± 0.1) X 10 ~2, respectively. The values of µ obtained by Toby and Nimoy1-5 were extrapolated to zero intensity and gave values of ho/h at 50, 100, 135, and 180°of

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A knowledge of the relation between hydrogen in the corrosion film and hydrogen pickup by the metal is important for understanding the hydriding behavior of zirconium alloys. The results obtained from isotope (deuterium, lithium, and boron) incorporation and exchange studies on oxides grown out- and in-reactor on Zr-2.5wt%Nb alloy are presented here. It is shown, using fourier transform infrared (FTIR) spectroscopy and secondary ion mass spectrometry (SIMS), that hydrogen in the corrosion film exists as surface hydroxyls and adsorbed water on oxide crystallites. These hydrated pathways on the oxide crystallite surfaces are random in occurrence, resulting from the nucleation and growth of oxide crystallites. The hydrogen ingress sites are the terminals of the pathways, and hydrogen pickup by the metal is a localized phenomenon, controlled by electron transfer at the oxide-alloy interface. Hydrogen in the bulk of the oxide exists as surface hydroxyls and adsorbed water in the pathways, which serve as fast transport routes for protons, lithium, and boron. Post-irradiation examinations on hundreds of pressure tubes removed during the Pickering Unit 3 large scale fuel channel replacement (P3LSFCR)-project included FTIR measurements. The pressure tubes were in service for 13.4 effective full power years (EFPY) of operation, and corrosion for the most part had been in the so-called post-transition regime of linear oxide growth. The spectra of oxide on the inside surfaces of the tubes near the outlets showed an absorption peak at 2600 cm-1, which is characteristic of deuteroxyl stretching vibration and hence deuterium in the oxide. The intensity of the absorption peak is found to be proportional to the oxide thickness, suggesting that the transport of deuterium through the bulk oxide had been similar for the oxides with different thermal and irradiation histories. However, the histograms of percent pickup for the axial locations 4.69 to 5.85 m near the outlet were asymmetric with slightly more than half of the channels showing 3 to 7% and the rest showing a wide range up to 40% pickup. Such a wide range in pickup cannot simply be attributed to the inherent property of the oxide-alloy interface. It is proposed that the corrosion of the Zr-2.5Nb alloy is normally associated with the generation of deuterium ingress sites whose density and capacity for pickup do not vary much with oxide thickness, i.e., the pickup shows a reasonable proportionality, varying over a small range of 3 to 7%, to oxide thickness. In the case of some tubes, other processes contribute to additional deuterium pickup. A comparison of the deuterium pickup at different axial locations indicates that the additional pickup is likely to be material related. The results from preliminary investigations on microstructural aspects suggest impurity inclusions as one of the main variables among offcuts from tubes showing high and low deuterium pickups. On the coolant side, the inclusions may function as localized windows for the entry of radiolytic deuterium produced in the hydrated pathways. On the annulus side, the inclusions may behave as defects or weak spots in the oxide, growing in nitrogen containing low partial pressures of water and deuterium on the outside surface. Additional slow deuteriding may occur from deuterium entry at the inclusion sites through the degraded oxide. The percent pickup for these tubes is likely to have been higher than the normal 3 to 7%, almost throughout their life in service.