Both liquid mercury and liquid lead-bismuth eutectic have been proposed as possible target materials for spallation neutron sources. During the 1950's and 1960's a substantial program existed at Brookhaven National Laboratory as part of the Liquid Metal Fuel Reactor program on the compatibility of bismuth, lead, and their alloys with structural materials. Subsequently, compatibility investigations of mercury with structural materials were performed in support of the development of Rankine-cycle mercury turbines for nuclear applications. The present talk will review our understanding of the corrosion/mass-transfer reactions of structural materials with these liquid-metal coolants. Topics to be discussed include the basic solubility relationships of iron, chromium, nickel, and refractory metals in these liquid metals, the results of inhibition studies, the role of oxygen on the corrosion processes, and specialized topics such as cavitation corrosion and liquid-metal embrittlement. Emphasis will be placed on utilizing the understanding gained in this earlier work in the development of heavy-liquid-metal targets for spallation neutron sources.

1997 TMS Annual Meeting: MATERIALS FOR SPALLATION NEUTRON SOURCES: Session III: Corrosion

STATIC CORROSION OF MARTENSITE/FERRITE AND AUSTENITIC STEELS IN MERCURY AT 300°C: Y. Dai, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland

Both liquid mercury and liquid lead-bismuth eutectic have been proposed as possible target materials for spallation neutron sources. During the 1950's and 1960's a substantial program existed at Brookhaven National Laboratory as part of the Liquid Metal Fuel Reactor program on the compatibility of bismuth, lead, and their alloys with structural materials. Subsequently, compatibility investigations of mercury with structural materials were performed in support of the development of Rankine-cycle mercury turbines for nuclear applications. The present talk will review our understanding of the corrosion/mass-transfer reactions of structural materials with these liquid-metal coolants. Topics to be discussed include the basic solubility relationships of iron, chromium, nickel, and refractory metals in these liquid metals, the results of inhibition studies, the role of oxygen on the corrosion processes, and specialized topics such as cavitation corrosion and liquid-metal embrittlement. Emphasis will be placed on utilizing the understanding gained in this earlier work in the development of heavy-liquid-metal targets for spallation neutron sources.

Pawel, S. J., DiStefano, J. R.; Manneschmidt, E. T., "Thermal gradient mass transfer of type 316L stainless steel and alloy 718 in flowing mercury", J. Nucl. Mater. 296, 1-3:210, July, 2001

Abstract

Thermal convection loops (TCLs) fabricated from 316L stainless steel (SS) and containing mercury and a variety of 316L coupons representing variable surface conditions and heat treatments have been operated continuously for periods up to 5000 h. In each case, the maximum TCL temperature was about 305 deg C, the minimum temperature about 240 deg C, and the Hg velocity was constant at either 1.2 m/min or 5 m/min, depending on the TCL cross-section diameter. Wetting of 316L by Hg was somewhat sporadic and inconsistent, and was generally encouraged by steam cleaning and /or gold-coating of specimens prior to testing as well as relatively high exposure temperatures. Interaction of 316L and Hg was observed to generate a porous surface layer substantially depleted of Ni and Cr which resulted in transformation to ferrite, but the maximum penetration detected for all of the test conditions corresponded to only about 60 -- 70 mu m/yr, with far less penetration for most exposures. In limited testing, alloy 718 was found more resistant to wetting/attack than 316L.

Zalavutdinov, R K; Dai, Y; Gorodetsky, A E; Bauer, G S; Alimov, V K; Zakharov, A P,"A study on martensitic and austenitic steels after exposure in mercury at 573 K up to 5000 hours", J. Nucl. Mater.], vol. 296, no. 1-3, pp. 219-224, 1 July 2001

Abstract

The chemical composition, structure and morphology of surface layers formed on stressed martensitic (F82H, MANET-II) and austenitic (316L) steel samples after exposure in static mercury with air or Ar inside the containers for 5000 and 2000 h, respectively, at 573 K have been studied by different surface analysis techniques (electron probe microanalysis (EPMA), scanning electron microscopy (SEM), reflected high energy electron diffraction (RHEED), X-ray diffraction (XRD), and secondary ion mass spectrometry (SIMS)). It has been shown that all three steels are oxidized (oxide thickness greatest on F82H and least for 316L) and covered with red HgO single crystals when air is present in the system. The oxidation of the steels and Hg can be suppressed by using Ar in the containers. Cracks have been found only at the notch roots of the 316L samples. There is no evident Hg corrosion observed.