Effect of lead on Inconel 600 and Incoloy 800 oxide layers formed in simulated steam generator secondary environments

A Mechanistic Study on Lead-Induced Passivity-Degradation of Nickel-Based Alloy

“…Although PbSCC is considered to be related to the breakdown of the passive film, 3,4,[9][10][11] limited research has been published on the detrimental effect of lead on the passivity of the SG tube alloys. Lead has been found to be able to incorporate into the passive films but how lead species enter the passive films is still unknown.…”

“…Lead has been found to be able to incorporate into the passive films but how lead species enter the passive films is still unknown. [10][11][12][13][14][15][16] Electrochemical measurements have shown that the presence of lead contamination promotes the anodic dissolution of nickel-based alloys close to the open-circuit potential and increases anodic current density of the passive state. 3,5,6,17 However, the mechanisms for the lead-induced passivity-degradation are as yet poorly understood, and no comprehensive theory has been reported to describe this phenomenon.…”

“…3,5,6,17 However, the mechanisms for the lead-induced passivity-degradation are as yet poorly understood, and no comprehensive theory has been reported to describe this phenomenon. 3,4,12,16 Some experimental results reported in the literature are contradictory, 3,11,12,14,16 even the phenomenon of leadinduced passivity degradation itself has not been well defined. 16,18 This is partially due to different chemistries and test conditions adopted by different researchers in their experiments.…”

Combined effect of gamma-radiation and pH on corrosion of Ni–Cr–Fe alloy inconel 600

“…The relative intensities of the Ni-2p, Cr-2p and Fe-2p peaks in the XPS survey spectra obtained at different pHs and radiation environments are shown in Fig. 5 [4][5][6][7][8]32,33,[48][49][50][51][52][53][54][55]. At pH 10.6 the enrichment ratio for Cr is lower and that for Fe is higher in the presence of radiation compared to those in the absence of radiation.…”

“…Although oxide film formation on Inconel 600 has been investigated extensively [4][5][6][7][8][32][33][34][35][36][37][38][39][40][41][42][43], most of these studies were performed over a limited range of environmental conditions. For example, oxide film formation has been studied in neutral pH water at 325 • C [32], in highly acidic and basic solutions at 350 • C and 320 • C [33], respectively and in pure water at 288 • C [5]. Because corrosion involves many different chemical and transport processes, and because pH, temperature and solution redox environment affect the rates of the individual processes differently [12], the overall corrosion rate measured over narrow ranges of pH and temperature cannot be directly applied to determine the corrosion rate beyond the studied conditions.…”