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

Abstract

The high corrosion behavior of the sputter-deposited amorphous or/and nanocrystalline WCr-(4-15)Ni alloys was investigated by corrosion tests, electrochemical measurements and X-ray photoelectron spectroscopy (XPS) including angle-resolved measurements in 12 M HCl at 30 o C, open to air. Particular attention was paid to the effects of tungsten, chromium and nickel metals addition on the surface composition of the passive films formed on the ternary alloys which is related to the corrosion-resistant as well as the anodic passivity of the alloys. Corrosion rates of the alloys (~ 0.85-3.00 x 10 -2 mm/y) are about four and three orders of magnitude lower than pure chromium and nickel, respectively, and even slightly lower than tungsten metal. Surface analyses by XPS including angle-resolved measurements revealed that the high corrosion resistance of the ternary W-Cr-(4-15)Ni alloys is mostly due to the formation of homogeneous passive oxyhydroxide films consisting of all alloying cations of the alloys. The beneficial effect of the simultaneous addition of chromium and tungsten is based mainly on the synergistic interaction between chromium and tungsten cations in the homogeneous oxyhydroxide passive films to improve the corrosion behavior as well as the passivity of the W-Cr-(4-15)Ni alloys in 12 M HCl.

Study of Corrosion Inhibition Mechanism of Sputter-Deposited W-42Cr-5Ni and Cr-10Zr-10w Alloys by Sodium Nitrite as Green Inhibitor in 0.5 M NaCl and 1 M NaOH Solutions

“…The instrument used and conditions subjected for the sputter deposition of these two alloys were same as those described elsewhere (Bhattarai, 2009(Bhattarai, , 2010b(Bhattarai, and 2010c. The composition, apparent grain size and structure of the alloys were analyzed by EPMA and XRD, respectively.…”

“…It was found that the apparent grain size of the W-42Cr-5Ni, Cr10Zr-10W alloys including tungsten, chromium, nickel and zirconium metals was found to be about 3.5, 29, 20, 40, 19 and 24 nm, respectively. Accordingly, the W-42Cr-5Ni and Cr-10Zr-10W alloys were characterized as the mixture of nanocrystalline and amorphous, and a nanocrystalline structures having the apparent grain size of 3.5 nm (Bhattarai 2009 and2010b) and 29 nm (Bhattarai 2010c andBhattarai 2011a), respectively.…”

“…Sputter-deposited W-42Cr-5Ni and Cr-10Zr-10W alloys X-ray diffractometer with CuKα radiation at    2 mode and electron probe microanalysis were used to determine the composition and structure of the sputter deposit of the W42Cr-5Ni and Cr-10Zr-10W alloys, , respectively (Bhattarai, 2009(Bhattarai, , 2010b(Bhattarai, and 2010c. Apparent grain size of the alloys was estimated using Scherrer's formula (Cullity, 1977).…”

“…It was reported that the sputter-deposited amorphous or/and nanocrystalline ternary W-xCr-yNi (Bhattarai, 2009(Bhattarai, , 2010bBhattarai and Kharel, 2009-10;Kharel and Bhattarai, 2009) and W-xZr-yCr (Aryal and Bhattarai, 2010cBhattarai, , 2011aBhattarai, , 2011bBhattarai and Aryal, 2011;Kumal and Bhattarai, 2010) alloys were spontaneously passivated showing significantly higher corrosion resistance than those of alloy-constituting elements in different aggressive solutions. In this context, the present work is focused to study the effects of the eco-friendly green corrosion inhibitor of sodium nitrite to control the corrosion of two sputterdeposited W-42Cr-5Ni and Cr-10Zr-10W alloys in 0.5 M NaCl and 1 M NaOH solutions open to air at 25ºC using corrosion tests and mechanism.…”

X-ray Photoelectron Spectroscopic Study on the Anodic Passivity of Sputterdeposited W-Ta Alloys in 12 M HCl

“…It has been reported that the high corrosion resistance of the sputterdeposited binary and ternary tungsten based alloys in 12 M HCl was based on the formation of new passive double oxyhydroxide films of tetravalent tungsten and alloyconstituting cations (Bhattarai 1998(Bhattarai , 2010Bhattarai et al 1995Bhattarai et al , 1997Bhattarai et al b, 1998. The tetravalent tungsten was 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.…”