Gallium Suboxide Vapor Attack of Chromium, Cobalt, Molybdenum, Tungsten, and Their Alloys at 1200°C

Authors: Kolman D.G.; Taylor T.N.; Park Y.S.; Stan M.; Butt D.P.; Maggiore C.J.; Tesmer J.R.; Havrilla G.J.

Source: Oxidation of Metals, Volume 56, Numbers 3-4, October 2001 , pp. 347-374(28)

Publisher: Springer

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Abstract:

Our prior work elucidated the failure mechanism of furnace materials (304 SS, 316 SS, and Hastelloy C-276) exposed to gallium suboxide (Ga_2O) and/or gallium oxide (Ga_2O_3) during plutonium–gallium compound processing. Failure was hypothesized to result from concurrent alloy oxidation/Ga compound reduction followed by Ga uptake. The aim of the current work is to screen candidate replacement materials. Alloys Haynes 25 (49 Co–20 Cr–15 W–10 Ni–3 Fe–2 Mn–0.4 Si, wt.%), 52 Mo–48 Re (wt.%), 62 W–38 Cu (wt.%), and commercially pure Cr, Co, Mo, W, and alumina were examined. Preliminary assessments of commercially pure W and Mo–Re suggest that these materials may be suitable for furnace construction. Thermodynamic calculations indicating that materials containing Al, Cr, Mn, Si, and V would be susceptible to oxidation in the presence of Ga_2O were validated by experimental results. The extent of attack (oxidation, Ga uptake, and elemental redistribution) cannot be predicted based on a simple rule of elemental mixtures—alloy composition plays a strong role. In contrast to that reported previously, an alternate reaction mechanism for Ga uptake, which does not require concurrent alloy oxidation, controls Ga uptake for certain materials. Due to the lack of thermodynamic data, calculations cannot quantitatively predict Ga uptake. However, a correlation between Ga solubility and uptake was noted.

Keywords: Gallium oxide; gallium suboxide; corrosion; chromium; cobalt alloys; molybdenum alloys; tungsten alloys

Language: English

Document Type: Regular paper

Affiliations: 1: Los Alamos National Laboratory, Los Alamos, New Mexico, 87545

Publication date: 2001-10-01

Gallium Suboxide Vapor Attack of Chromium, Cobalt, Molybdenum, Tungsten, and Their Alloys at 1200°C

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