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Property Measurements of the NaCl-PuCl 3 Molten Salt System
Thermal properties of several compositions of the binary NaCl-PuCl 3 salt were measured to confirm the eutectic composition and provide high quality data for use by MSR developers. The PuCl 3 was generated by reducing PuO 2 to plutonium metal in the presence of calcium metal and then chlorinating the metallic plutonium with NH 4 Cl. The resulting PuCl 3 was used to make seven binary NaCl-PuCl 3 compositions with between 59.9 mol % PuCl 3 (Salt 1) and 20.0 mol % PuCl 3 (Salt 7). The eutectic temperature was measured to be 457 ± 4 °C by onset determination in DSC analyses of the seven mixtures, which is consistent with the values in the literature. Additional transitions were observed at approximately 332 and 363 °C in analyses of the PuCl 3 -rich compositions (Salts 1-3) at about 376 and 439 °C in analyses the Na-rich compositions (Salts 4-7). The solid state heat capacity decreased with increasing PuCl 3 content. The liquid state heat capacity was measured for Salt 3 (37.4 mol % PuCl 3 ) and Salt 4 (38.3 mol % PuCl 3 ). A higher heat capacity was measured for Salt 4 and measurements with both salts showed a positive correlation with temperature between 520 and 730 °C. Cells fabricated from nickel and molybdenum for use in DSC measurements at high temperatures could not be adequately sealed because these materials are not sufficiently malleable, even after high temperature annealing. It is recommended that future development focus on corrosion-resistant materials that have mechanical and thermal properties similar to the commercially available gold cells, such as Pt-Rh (80–20) and pure platinum. Those materials are chemically inert, soft, and malleable like gold, but have melting temperatures higher than 1000 °C (Rakhtsaum, 2013). Use of the Pt-Rh alloy should be evaluated first based on superior machinability for making precision parts and its current use in commercial DSC high temperature crucibles. The commercial Pt-Rh cells are not hermetically sealable, but it is expected that cells made from thinner stock can be sealed.
New Fiber Reinforced Waterless Concrete for Extraterrestrial Structural Applications
Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction mate: iii an attractive alternative to conventional concrete as it does not require water For the purpose of this paper it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, brick and beam elements. Glass fibers produced from regolith were used as a reinforcement to improve the mechanical properties of the sulfur concrete. Glass fibers and glass rebar were produced by melting the lunar regolith simulant. Lunar regolith stimulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline 46100 high temperature MoSi2 furnace at melting temperatures of 1450 to 1600G. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The viability of sulfur concrete as a construction material for extraterrestrial application is presented. The mechanical properties of the glass fiber reinforced sulfur concrete were investigated.
Mechanical Properties and Durability of "Waterless Concrete"
Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and by oxidation soil iron and sulfur can be produced. Iron can be used to reinforce the sulfur concrete. Sulfur concrete specimens were cycled between liquid nitrogen (approximately 191 C) and room temperature (approximately 21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (approximately 21 C) and approximately 101 C. Test results showed that due to temperature cycling, compressive strength of cycled specimens was 20% of those non-cycled. Microscopic examination of the fracture surfaces from the cycled samples showed clear de-bonding of the sulfur from the aggregate material whereas it was seen well bonded in those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibers. The glass fibers from lunar regolith simulant was melted in a 25 cc Pt-Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to 1 hour. Glass fibers were cast from the melt into graphite crucibles and were annealed for a couple of hours at 600 C. Glass fibers and small rods were pulled from the melt. The glass melt wets the ceramic rod and long continuous glass fibers were easily hand drawn. The glass fibers were immediately coated with a protective polymer to maintain the mechanical strength. The glass fibers were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Prisms beams strengthened with glass fibers were tested in 4-point bending test. Beams strengthened with glass fiber showed to exhibit an increase in the flexura strength by as much as 45%.
Materials Data on Pt3Rh by Materials Project
Pt3Rh is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Rh is bonded to twelve equivalent Pt atoms to form RhPt12 cuboctahedra that share corners with twelve equivalent RhPt12 cuboctahedra, edges with twenty-four equivalent PtPt8Rh4 cuboctahedra, faces with six equivalent RhPt12 cuboctahedra, and faces with twelve equivalent PtPt8Rh4 cuboctahedra. All Rh–Pt bond lengths are 2.79 Å. Pt is bonded to four equivalent Rh and eight equivalent Pt atoms to form PtPt8Rh4 cuboctahedra that share corners with twelve equivalent PtPt8Rh4 cuboctahedra, edges with eight equivalent RhPt12 cuboctahedra, edges with sixteen equivalent PtPt8Rh4 cuboctahedra, faces with four equivalent RhPt12 cuboctahedra, and faces with fourteen equivalent PtPt8Rh4 cuboctahedra. All Pt–Pt bond lengths are 2.79 Å.
Materials Data on Pt3Rh by Materials Project
Pt3Rh is Copper-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Rh is bonded to twelve Pt atoms to form RhPt12 cuboctahedra that share corners with four equivalent RhPt12 cuboctahedra, corners with eight equivalent PtPt8Rh4 cuboctahedra, edges with eight equivalent RhPt12 cuboctahedra, edges with sixteen equivalent PtPt8Rh4 cuboctahedra, faces with four equivalent RhPt12 cuboctahedra, and faces with fourteen PtPt8Rh4 cuboctahedra. All Rh–Pt bond lengths are 2.79 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded to four equivalent Rh and eight Pt atoms to form PtPt8Rh4 cuboctahedra that share corners with twelve equivalent PtPt8Rh4 cuboctahedra, edges with eight equivalent RhPt12 cuboctahedra, edges with sixteen PtPt8Rh4 cuboctahedra, faces with four equivalent RhPt12 cuboctahedra, and faces with fourteen PtPt8Rh4 cuboctahedra. All Pt–Pt bond lengths are 2.79 Å. In the second Pt site, Pt is bonded to four equivalent Rh and eight equivalent Pt atoms to form PtPt8Rh4 cuboctahedra that share corners with four equivalent PtPt8Rh4 cuboctahedra, corners with eight equivalent RhPt12 cuboctahedra, edges with twenty-four PtPt8Rh4 cuboctahedra, faces with six equivalent RhPt12 cuboctahedra, and faces with twelve PtPt8Rh4 cuboctahedra.