Electrochemical and XPS studies on the passivation behavior of sputter-deposited W-Cr Alloys in 12 M HCl solution

X-ray Photoelectron Spectroscopic Analyses on the Corrosion-Resistant W-Cr-Ni Alloys in 12 M HCl

“…The photo-ionization cross-section of the Cr 2p 3 Figure 1 shows the corrosion rates of the sputterdeposited W-Cr-(4-15)Ni alloys after immersion for 168 h in 12 M HCl at 30 o C. Corrosion rates of the sputter-deposited binary W-18Cr, W-75Cr and W-15Ni alloys including pure tungsten, nickel and chromium metals are also shown for comparison. 8,10 All the examined W-Cr-(4-15)Ni alloys show about four and three orders of magnitude lower corrosion rate than those of chromium and nickel metal, respectively, and slightly lower corrosion rate than that of tungsten metal. However, the corrosion rates of the W-Cr-(4-15)Ni alloys are slightly increased with increasing the chromium content in the ternary W-Cr-Ni alloys.…”

“…It has been reported that 10 at% or less tungsten addition was enough to cause spontaneous passivation of the sputter-deposited W-Cr alloys and they showed higher corrosion resistance than those of tungsten and chromium. 8 It has been also reported that the sputterdeposited amorphous/nanocrystalline W-Ni alloys were passivated spontaneously and showed high corrosion resistance in concentrated hydrochloric acids. 10 The significant improvement of the corrosion resistance of the binary W-Cr 8 and W-Ni 10 alloys was attributed to the formation of double oxyhydroxide passive films of the alloy-constituting elements from the surface sensitive XPS analyses.…”

“…This allows us to examine the formation of homogeneous or heterogeneous surface films formed on the alloys. [2][3][4][5][6][7][8][9] A non-destructive angleresolved XPS technique has been used by a number of researchers to gain information about in-depth concentration profiles of the passive films. In principle, the depth information of the passive film depends on the effective escape depth of photoelectrons, which increases with increase in the take-off angle of photoelectrons relative to the surface of the specimen.…”

X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputter-deposited W-Nb Alloys in 12 M HCl Solution

“…It has been reported that the high corrosion resistance of the sputter-deposited tungsten−based binary [18][19][20][22][23][24][25] and ternary [26,27] alloys in 12 M HCl was based on the formation of new passive double oxyhydroxide films of tetravalent tungsten and alloy-constituting cations. The tetravalent tungsten is the main oxidation state of tungsten for these tungsten-based binary alloys at +0.2 V (SCE) or lower potentials, while the hexavalent tungsten is the main oxidation state of tungsten at +0.4 V (SCE) or higher potentials in hydrochloric acid solutions.…”

High Corrosion Resistant Ni-Based Glassy Alloys in Boiling Nitric Acid Solutions

“…The absence of crystalline defects and the chemically homogeneous single-phase nature of amorphous alloys lead to the formation of a uniform passive film and hence are responsible for high corrosion resistance. Since then, various types of high corrosion resistant amorphous, glassy alloys and bulk metallic glasses have been developed by sputter deposition, melt spinning and copper-mold casting methods, as exemplified for Ni-Crmetalloid, 2,3) Ni-valve metal, 4,5) (Cr,Mo,W)-valve metal, [6][7][8] Fe-Cr-Mo-P-C 9,10) alloy systems, which possess superior corrosion resistance in concentrated hydrochloric acid solutions. However, there have been no data about corrosion resistance of glassy alloys in boiling nitric acid solutions.…”