XPS study of oxides formed on nickel‐base alloys in high‐temperature and high‐pressure water

Abstract

The aim of this work is to characterize the oxidation behaviour of different nickel-base alloys exposed to high-temperature and high-pressure water for short oxidation times. The behaviour of Alloy 600 (74% Ni, 16% Cr, 9% Fe), Alloy 690 (60% Ni, 30% Cr, 9% Fe) and Alloy 800 (47% Fe, 32% Ni, 21% Cr) exposed to simulated, pressurised water reactor primary water at 325• C has been compared. From the combination of chemical and structural data obtained by XPS, nuclear reaction analysis and scanning electron microscopy, the chemical composition and the morphology of the oxide formed on the surfaces have been determined. All alloys present a duplex oxide layer composed of Fe-rich crystals in the external layer and an inner Cr-rich layer that is compact and continuous.

Photoelectrochemical study of nickel base alloys oxide films formed at high temperature and high pressure water

“…The band gap values of nickel, chromium and iron oxides, which have been observed [1][2][3][4][5][6][7][8][9][10][11][12][13][14] or could be expected to form during the corrosion process of nickel base alloys under the simulated PWR primary conditions, have been collected on the basis of a literature research [19,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

“…During the corrosion process, a passive layer is formed, whose structure and properties play a key role on degradation phenomena such as nickel release in the water, which has for consequence an increase of the contamination, or such as stress corrosion cracking initiation and growth. Different papers describe the oxide film growing on nickel base alloys in PWR simulated primary water as a duplex structure [1][2][3][4][5][6][7][8][9][10][11][12]. The internal layer corresponds to an oxide rich in chromium whereas the outer one, which is assumed to be formed by precipitation process [3,6], is rich in iron or nickel.…”

Influence of dissolved oxygen concentration on the oxide film formed on Alloy 690 in high temperature water

“…7a), the thicknesses of oxide films can be estimated. The point where the intensity of oxygen level reaches 50% of its initial value is taken as the interface between the oxide film and metal substrate [4,10]. The oxygen level after 30 s sputtering was taken as the initial oxygen content and the sputtering time when the oxygen content was half of this value corresponded to the interface.…”

“…The oxidation behavior of nickel-base alloys has been one of the hot topics because the oxide films formed are important to their performance. Up to now, in order to elucidate the oxidation process, some studies have been done to analyze the formed oxide films [2][3][4][5][6][7][8][9]. And the effects of different water chemistry parameters such as dissolved hydrogen (DH) [10][11][12][13][14], pH [15,16], temperature [15,17,18], Li concentration [19] and Zn injection [20,21] on the oxidation behaviors of Ni-base alloys have also been investigated.…”

Corrosion Behavior of Alloy C‐276 in Supercritical Water

“…Owing to the superior mechanical properties and corrosion performance in high temperature, nickel-base alloys seemed to be the suitable materials used in SCWR [2][3][4]. us, essentially, nickel-base alloys are in high content in Ni, Cr, which could increase the oxidation and corrosion resistance of the nickel-base alloys at high temperatures [5][6][7][8][9][10][11][12][13][14][15]. Up to now, the corrosion behaviors of nickel-base alloys in the supercritical water have been intensely investigated in literature [3,4,[16][17][18].…”