In order to understand corrosion behavior of stainless steel in BWR reactor water conditions, characteristics of oxide films on stainless steel specimens exposed to H 2 O 2 and O 2 in high temperature water were determined by multilateral surface analyses, i.e., SEM (scanning electron microscope), LRS (laser Raman spectroscope), SIMS (secondary ion mass spectroscope) and STEM-EDX (scanning transmission electron microscope). The following points were experimentally confirmed. (1) Oxide layers were divided into inner and outer layers: Outer layers of the specimen exposed to 100 ppb H 2 O 2 consisted of larger corundum type hematite (-Fe 2 O 3) particles, while inner layers consisted of very fine Ni rich magnetite (Fe 3 O 4). Outer layers of the specimen exposed to 200 ppb O 2 consisted of larger magnetite mixture particles, while inner layers consisted of fine Cr rich magnetite. (2) Outer oxide layers consisted of oxide particles. The oxide particles depositing on the specimens exposed to 100 ppb H 2 O 2 were divided into two groups, i.e., a larger particle group and a smaller particle group. For other specimens, the diameter distribution of depositing particles was a single peak. Particle density and size were changed by oxidant concentration. The average diameter of the particles (that of the smaller group only for the specimen expose to 100 ppb H 2 O 2) decreased with [O 2 ] and [H 2 O 2 ]. (3) Total oxide film thickness decreased with [H 2 O 2 ] and increased with [O 2 ]. (4) A larger dissolution rate at higher [H 2 O 2 ] resulted in a thinner oxide film with smaller particles and larger hem-atite particles.
A high temperature high pressure water loop, which can control H 2 O 2 concentration with minimal oxygen (O 2) coexistence, has been fabricated. In order to evaluate the effects of hydrogen peroxide (H 2 O 2) on intergranular stress corrosion cracking. Not only static responses, i.e., electrochemical corrosion potential (ECP), of the stainless steel specimens exposed to H 2 O 2 and O 2 at elevated temperatures but also their dynamic responses, i.e., frequency dependent complex impedances (FDCI), were measured. The conclusions obtained by the experiments are as follows. (1) The ECP measured for the SUS 304 specimen exposed to 100 ppb H 2 O 2 reached the saturated level in 50 h, showed a larger value than the specimen exposed to 200 ppb O 2 and kept the same ECP level when the H 2 O 2 concentration was decreased to 10 ppb. (2) The FDCI measured for the specimen exposed to 100 ppb H 2 O 2 showed saturation in the low frequency semicircles; this behavior was determined by the electric resistance of the oxide film and caused by saturation of oxide film thickness. Behavior for the specimen exposed to 200 ppb O 2 was determined by the resistance of oxide dissolution, which was much larger than that for the specimen exposed to H 2 O 2. (3) The ECPs of the specimens exposed to 200 ppb O 2 after 200-h exposure to 100 ppb H 2 O 2 were higher than those exposed to only 200 ppb O 2 due to memory effects on oxide films. The specimens with pre-exposure to 200 ppb O 2 did not show these memory effects.
A new type of ionic liquid salt bridge (ILSB) based on a mixture of pentyltripropylammonium bis(pentafluoroethanesulfonyl)amide, [N(3335)(+)][C(2)C(2)N(-)], and heptadecafluorodecyltrioctylphosphonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [TOPH(+)][TFPB(-)], shows a stable phase-boundary potential (Δ(IL)(W)φ) between the ILSB and an aqueous solution of MCl (M = H(+), Li(+), Na(+), and K(+)) over the concentration range from 0.05 mM to 0.5 M with an averaged excursion in 1 h of ±0.3 mV. The reproducibility of Δ(IL)(W)φ is ±0.6 mV on average (95% confidence interval) in KCl solutions in this concentration range. The mixing of the two different types of salts not only increases the stability of the phase-boundary potential but provides us with more freedom in selecting potential-determining salts to design and customize ILSBs for different purposes.
In order to understand corrosion behavior of stainless steel in BWR reactor water conditions, characteristics of oxide films on stainless steel specimens exposed to H 2 O 2 and O 2 in high temperature water were determined by multilateral surface analyses, i.e., SEM (scanning electron microscope), LRS (laser Raman spectroscope), SIMS (secondary ion mass spectroscope) and STEM-EDX (scanning transmission electron microscope). The following points were experimentally confirmed.(1) Oxide layers were divided into inner and outer layers: Outer layers of the specimen exposed to 100 ppb H 2 O 2 consisted of larger corundum type hematite (-Fe 2 O 3 ) particles, while inner layers consisted of very fine Ni rich magnetite (Fe 3 O 4 ). Outer layers of the specimen exposed to 200 ppb O 2 consisted of larger magnetite mixture particles, while inner layers consisted of fine Cr rich magnetite.(2) Outer oxide layers consisted of oxide particles. The oxide particles depositing on the specimens exposed to 100 ppb H 2 O 2 were divided into two groups, i.e., a larger particle group and a smaller particle group. For other specimens, the diameter distribution of depositing particles was a single peak. Particle density and size were changed by oxidant concentration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.