Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Mo”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Effect of melt spinning on grain size and texture in Ni-Mo alloys

Chill-block melt-spun ribbons of Ni-Mo alloys with Mo contents of 8 to 41.8 wt pct have been examined for microstructure and texture dependence on processing conditions. Linear features observed in grains solidified with a planar liquid-solid interface at the quench side of the ribbons have been identified to be due to the twins on the (111)gamma plane formed during solidification. Grain size variation with the wheel surface speed and the alloy composition has been studied. The crystallographic texture on the quench side and the free surface side of the ribbons has been investigated.

Tewari, S. N.↗
NASA NTRS1992

Fabrication and analysis of Mo-Si multilayers

Mo-Si multilayers have been fabricated in our laboratory for reflecting various soft X-ray wavelengths. Several normal incidence mirrors have been produced for a solar sounding rocket flight. Using properly shaped masks on 3-inch diameter dc magnetrons, we can produce multilayers of a similar size having a uniformity of better than +/- 3 percent over their entire surface area. Peak reflectance of the multilayers are as high as 42 percent at 171 A. Efforts are underway to deposit several layers of different period on top of the multilayers in order to attenuate the reflection of 304 A, a very bright line of He II in the solar spectrum. In the interim, we have made a Mo-Si mirror that reflects at 304 A. In addition to obtaining information on the solar corona at this wavelength, this will greatly reduce the effects of the He II line when its image is appropriately subtracted from others.

Shing, L.↗
NASA NTRS1993

Core formation in the Moon: The mystery of the excess depletion of Mo, W and P

We have evaluated siderophile element depletion models for the Moon in light of our improved statistical treatment of siderophile element abundance data and new information on the physics of core formation. If core formation occurred in the Moon at the large degrees of partial melting necessary for metal segregation, according to recent estimates, then a significant inconsistency (not seen in the eucrite parent body) exists in the depletion of the incompatible siderophile elements Mo, W, and P, compared to other siderophile elements in the Moon. The siderophile data, with the exception of Mo, are most consistent with terrestrial initial siderophile abundances and segregation of a very small core in the Moon. Our improved abundance estimates and possible explanations for these discrepancies are discussed.

Newsom, H. E.↗
NASA NTRS1995

NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems

Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

Johnson, D. R.↗
NASA NTRS1997

Oxidation and Emittance Studies of Coated Mo-Re

A commercially available Fe-Cr-Si coating (R512E) and a silicide coating were evaluated regarding their ability to protect Mo-Re from oxidation. The R512E coating provided very good oxidation protection at 1260 C in atmospheric air. Oxidation tests were also performed at Mach 4 in the HYMETS facility at NASA Langley Research Center where again the R512E provided good oxidation protection but for much shorter times. Emittance measurements as a function of wavelength were also obtained for the R512E coating on Mo-Re after exposure to the Mach 4 environment at 1150 C and 1230 C.

Glass, David E.↗
NASA NTRS2005

Status of Genesis Mo-Pt Foils

A total of 8,000 sq cm of Mo-coated Pt foils were exposed to solar wind for 884 days by the Genesis mission. Solar wind ions were captured in the surface of the Mo. Our objective is the measurement of long-lived radionuclides, such as Be-10, Al-26, Cl-36, and Mn-53, and short-lived radionuclides, such as Na-22 and Mn-54, in the captured sample of solar wind. The expected flux of these nuclides in the solar wind is 100 atom/sq cm yr or less. The hard landing of the SRC (Sample Return Capsule) at UTTR (Utah Test and Training Range) has resulted in contaminated and crumpled foils. Here we present a status report and revised plan for processing the foils.

Nishiizumi, K.↗
NASA NTRS1966

Quenched-in defects in Mo-35Re

Feasibility of using quenched-in defect technique to study effect of rhenium on vacancy clustering in Mo-35Re

CRYSTAL STRUCTURE DEFECT↗