Chromium depth profile

Figure 9. Chromium depth profile in Fel3Cr after normal (a) and controlled or modified annealing (b). (Reproduced, with permission, from Ref. 43. Copyright...

Fig. 3.22. Depth profile of a passivation layer on high-purity chromium. The 0 layer is on the top, the 0 layer at the interface with the metal.

Figure 9.10 Depth profile for a non-conducting chromium oxide layer on chromium based alloy measured by rf CDMS. (A. I. Saprykin, J. S. Becker et ai, Fresenius /. Anal. Chem., 358, 145 (1997). Reproduced by permission of Springer Science and Business Media.)...

Figure 14.33 Depth profile analysis of a Nichrome film on a silicon substrate. The outermost layer shows both Cr and oxygen, probably as a stable chromium oxide layer. The Ni and Cr (the Nichrome film) signals drop off at about 175 A while the Si substrate signal starts to appear, indicating the approximate film thickness. (From Weber.)...

Fig. 17 (a, b) Composition-depth profiles for the major elements found in chromium-chromate CCCs. (From Ref [94].) (c) A CCC structural model... 

Fig. 8. AES Depth Profile of the Aluminum Foil Treated by Aqueous Chromium(III) Fumarato-Coordination...

GD-TOFMS depth profile of Figure 41.6B reveals the chromium,phosphorus, and chlorine-containing layers at approximately 45,260, and 285 nm, respectively, below the surface of anodic film, with the copper-enriched layer immediately beneath the alumina film and the boron-doped outer region, of about 160 nm thickness. 

Figure 6.21 Auger depth profiles measured on Fe-25Cr alloy anodically passivated at 0 V and at 0.5 V in solutions of 0.4 M Na2S04 + 0.1 M H2SO4 and of 1 M NaOH, respectively. In acid solution the passive film is enriched in chromium oxide while in alkaline solution it contains mostly iron oxide [21].

The chemical composition of passive films on Fe-Cr alloys depends strongly on the corrosive environment and on the applied potential. In acid media the films become enriched in chromium oxide, while in alkaline media they contain more iron oxide. The Auger depth profiles of Figure 6.21 illustrate this observation. They were measured on a Fe-25Cr alloy after 1 hour anodic polarization in an acid sulfate... 

The above AES results can be correlated to bond performance. Hsu et found that the DQSK adherends, containing the higher concentration of silicon, showed interfacial failure, while only cohesive failure was observed for CRS adherends. The chromium-to-iron ratios, determined from the depth-profile study of pretreated steel surfaces,correlated with the wedge test performance as shown in Figure 24, with minimal crack extension in samples with high Cr/Fe ratios. 

The most relevant findings of the SIMS analyses as reported in the literature [12,38,39] are the depth profiles of chromium and their consistency with the trends of oxidation kinetics. The Cr depth profiles obtained after 52 hours of oxidation are presented in the Figures 8-10. At each of the oxidation temperatures, Cr content of the irmer layer of nanocrystaUine Fe-lOCr alloy was invariably found to be considerably higher than the highest Cr content in the inner layer of microcrystalline Fe-lOCr alloy. This provides an explanation for the greater oxidation resistance of the nanocrystaUine Fe-lOCr alloy (as shown in Figures 8-10), since oxidation resistance of Fe-Cr alloys is governed primarily by the Cr content of the thin oxide scale. 

The serious accumulation of chromium within the film corresponds to XPS results, but provides a much higher depth resolution. The depth profile shows a maximum at the centre of the film which shifts to the surface with passivation time, even after days due to the slow dissolution of Fe(III) and the negligibly small dissolution of Cr(III) from the passive layer (Strehblow et al., 1994). 

Figure 37. AES depth profile recorded from an amorphous, bright, chromium deposit annealed at 100°C and implanted with a dose of 90 keV, 4 x lO N cm" , (From Ref. 109.)...

In conclusion, the effect of ion bombardment on amorphous Cr-O-Si layers is manifested in major surface chemical and short-range structural changes. Ar bombardment can be used to create chromium silicide clusters. To avoid such ion-beam-induced transformations, depth profiling by wet chemical etching may be preferable. 

Figure 9. Comparative SIMS molecular ion depth profiles of oxide films on Alloys 600 and 800. The arrow indicates an enrichment of chromium oxide at the interface.

Takenaka, M.,Tomita, M., Kubota, A., and Tsuchiya, N. (1994). Depth profiling of ultratrace chromium, iron, rrickel, and copper in silicon wafers by electrothermal vaporization/ICP-MS. Bunseki Kagaku 43(2), 173. 

AES sputter depth profile through an iron/copper/chromium multilayer structure. Each layer is 5 nm thick (Courtesy of Thermo Fisher Scientific)... 

If a sample of polycrystalline material is rotated during the sputtering process, the individual grains will be sputtered from multiple directions and nonuniform removal of material can be prevented. This technique has been successfully used in AES analysis to characterize several materials, including metal films. Figure 9 indicates the improvement in depth resolution obtained in an AES profile of five cycles of nickel and chromium layers on silicon. Each layer is about 50 nm thick, except for a thinner nickel layer at the surface, and the total structure thickness is about 0.5 pm. There can be a problem if the surface is rough and the analysis area is small (less than 0.1-pm diameter), as is typical for AES. In this case the area of interest can rotate on and off of a specific feature and the profile will be jagged. 

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