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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8

Magnetic properties of Apollo 16 samples and implications for their mode of formation

The Apollo 16 crystalline rocks have a greater average percentage of metallic iron than any other lunar material and are the most reduced in terms of their metallic iron/total iron ratio. They have greater metal content than the mare basalts, the only primary igneous rocks on the moon, and more iron metal than the associated Apollo 16 breccias and soils. This fact and the relatively coarse grain size suggest reduction of the iron during the formation of the crystalline rocks, probably during melts and partial melts in an impact base surge deposit.

Pearce, G. W.↗

The electrical and magnetic properties of /TTF//I/-sub 0.71

The synthesis and transport properties of the salts (TTF) (iodine)-sub x have been investigated. These salts are quasi-one-dimensional compounds containing cation radicals only, in contrast to the cation radical-anion radical systems such as (TTF)(TCNQ). The phase diagram of (TTF)(I)-sub x is discussed, and found to consist of two nonconducting, stoichiometric phases, x = 2.0 and 3.0, and two conducting, nonstoichiometric phases, x = 0.71 and 2.3. The transport properties of (TTF)(I)-sub 0.71 are discussed in detail. This phase is highly conducting, undergoes a sharp transition to a less conducting state at 210 K, and exhibits an unusual hysteresis in some of the transport properties upon thermal cycling. The nature of the high-temperature ground state is examined.

Somoano, R. B.↗

The influence of containerless undercooling and rapid solid-state quenching on the superconductive and magnetic properties of some clustering alloy systems

The properties of clustering alloy systems and the manner in which they are influenced by rapid quenching from a containerless undercooled melt are discussed. It was postulated that rapid quenching under such conditions would result in highly disordered metastable alloys, and furthermore, that alloys in such conditions would possess physical properties characteristically different from those of alloys in the annealed equilibrium state. The scope of the program is essentially to gauge the influence of containerless undercooling on the submicrostructure of clustering-type alloys, using certain physical properties as diagnostic tools. Microstructures and macrostructures were to be examined using optical- and scanning-electron microscopy.

Collings, E. W.↗

The Influence of Containerless Undercooling and Rapid Solid-State Quenching on the Superconductive and Magnetic Properties of Some Clustering Alloy Systems

The potential of the 100-meter drop-tube for producing materials with new and important properties by their rapid solidification containerless undercooling was investigated. Materials produced exhibit evidence of very rapid quenching. The importance of rapid quenching in producing materials of considerable scientific and technological interest is emphasized. It is indicated that containerless undercooling, using at first a drop tube and eventually a space-shuttle-serviced orbiting laboratory, will provide another powerful approach for rapid quenching. A special advantage of the drop tube is that the microgravity condition is imposed ballistically; it is therefore possible to obtain either spherical samples by allowing solidification to take place in flight, or splats by allowing the sample material while still in undercooled liquid form to impact a stationary quench plate.

Collings, E. W.↗

Conduction investigations into the magnetic properties of matter

The thermal analysis of a heat exchanger for heating air to temperatures on the order of 3000 C for use in NASA's high temperature wind tunnel is presented. It was ascertained that an externally finned shell-and-tube type of heat exchanger with counterflow could be considered for this application. The methods of estimating the convective heat transfer coefficients are outlined in this report. As a part of thermal design the required size of heat exchanger was predicted. As a result of the extreme length required (approx. = 1/2 km), it was determined that a conventional heat exchanger may not be the most suitable tool for this application.

Chagini, H.↗