Survey of Refractory Uranium Compounds

Abstract

Chemical and physical data on twenty binary uranium compounds that may prove suitable for refractory nuclear fuels were assembled. The compounds were those with aluminum, boron, carbon, iron, nickel, nitrogen, siliqon, or sulfur.

Thermophysical properties of U3Si2 to 1773 K

“…Good agreement is observed with the data set collected here except for the values near 1000 K. For the U 3 Si 2 phase, there is no physical explanation for deviations in this temperature range, and it is expected that this observation is an experimental anamoly. Loch et al determined the technical coefficient of thermal expansion referenced to 273 K as a function of temperature to 1223 K, which varied from 15.2 Â 10 À6 K À1 to 14.6 Â 10 À6 K À1 and is within 9% of the value determined in this study [16]. Specific details regarding the sample fabrication route and microstructural information were not included in Loch's investigation making comparison difficult with this and other investigations in the literature.…”

“…Based on other U-Si binary compound Debye temperature values [13,21], it is estimated that U 3 Si 2 has an approximate Debye temperature of 200 K, which is below the temperature range investigated in this study. Contributions to the heat capacity from the dilational term are approximated using the well-known formula C d ¼ a ) - [16], and ( ) - [17].…”

Oxidation behavior of U-Si compounds in air from 25 to 1000 C

“…Silicides are typically arc melted from the pure metals, though historically little data is provided to indicate purity of the resulting materials. [9,10] Previous efforts used primarily x-ray diffraction (XRD) to analyze the source material and the oxidation products. Some studies do not state source material purity or phase analysis and rather provide times and temperatures of disintegration of the U-Si compounds.…”

“…Some studies do not state source material purity or phase analysis and rather provide times and temperatures of disintegration of the U-Si compounds. [9] Earliest investigations concluded that U 3 Si, U 3 Si 2 , and USi would disintegrate in air exposure at or above 400 ○ C in under 7.5 hr. [9] Snyder et al state that uranium and uranium alloys oxidize per Equation 1.…”

“…[9] Earliest investigations concluded that U 3 Si, U 3 Si 2 , and USi would disintegrate in air exposure at or above 400 ○ C in under 7.5 hr. [9] Snyder et al state that uranium and uranium alloys oxidize per Equation 1. [10] The power-law oxidation behavior indicates that the silicides oxidize linearly (n=1), parabolically (n=.5), etc for a given set of conditions.…”