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Results for “Al-C”

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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7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Control of interfaces in Al-C fibre composites

The interface of Al-C fiber composite was modified by coating a silver layer on the surface of carbon fibres prior to making composites, in an attempt to improve the wettability between molten aluminum and carbon fibers during infiltration. An electroless plating technique was adopted and perfected to provide a homogeneous silver coating on the carbon fiber surface. Al-C fiber composites were prepared using a liquid infiltration technique in a vacuum. It was found that silver coating promoted the wetting between aluminum and carbon fibers, particularly with polyacrylonitrile-base carbon fibers. However, due to rapid dissolution of silver in molten aluminum, it was believed that the improved infiltration was not due to the wetting behavior between molten aluminum and silver. The cleaning of the fiber surface and the preservation of the cleaned carbon surface with silver coating was considered to be the prime reason for the improved wettability. Interfacial reactions between aluminum and carbon fibers were observed. Amorphous carbon was found to react more with aluminum than graphitic carbon. This is believed to be because of the inertness of the graphitic basal planes.

Warrier, S. G.↗
DOE OSTI2024

Multi-catalytic active site biochar-based catalysts for glucose isomerized to fructose: Experiments and density functional theory study

In this study, this work provides an innovative method for preparing different isomerization catalysts by impregnating different proportions of MgCl 2 and AlCl 3 and combining different K compounds on cellulose-derived biochar, followed by pyrolysis. Results show MgO and Al(OH) 3 existing in 4 Mg- 1 Al-C catalyst can obtain better catalytic effect on glucose isomerization than the singe of Al presenting in 0 Mg- 1 Al-C catalyst. Moreover, the synergism effects of the multi-catalytic active sites such as β-, γ -Al(OH) 3 , KCl, MgO, and K 4 H 2 (CO 3 ) 3 in Mg-Al-KHCO 3 -C catalyst can further lead to an increase in glucose isomerization, compared to the 4 Mg- 1 Al-C catalyst. The X-ray diffraction results present that the value of O/Al in Mg-Al-KHCO 3 -C catalyst is as high as 13.38, which provides many unsaturated acidic catalysis sites and benefits the glucose isomerization. Simultaneously, the TPD results reveal that the main active sites (MgO, Al(OH) 3 , and K 4 H 2 (CO 3 ) 3 ) in Mg-Al-KHCO 3 -C catalyst can provide weakly acidic and basic sites and avoid strongly acidic and basic sites to excessively attack the glucose. Based on the DFT analysis, the results indicate that the MgO has a great effect on the ring-opening reaction to form acyclic glucose, while Al(OH) 3+ has a great effect on promoting acyclic glucose hydrogen transfer isomerized to form fructose. Compared to other carbon-based metal catalysts, the prepared Mg-Al-KHCO 3 -C has excellent catalytic performance, which gives a higher fructose yield (38.7%) and selectivity (87.72%) and glucose conversion (44.12%) at 100 °C in 30 min. In this study, we develop a highly efficient Mg-Al-K-biochar catalyst for glucose isomerization and provide an efficient method for cellulose valorization.

36 MATERIALS SCIENCE↗
NASA NTRS1985

A review of rapid solidification studies of intermetallic compounds

A review of rapid solidification studies of high-temperature ordered intermetallic compounds is presented. Emphasis is on the nickel - and iron- aluminides which are of potential interest as structural materials. The nickel-base aluminides which have been rapidly solidified exhibit changes in grain size, compositional segregation, and degree of long range order (as reflected in APB size and distribution) which markedly affect mechanical properties. Some experiments indicate the formation of a metastable L1(2) phase in rapidly solidified Fe-(Ni,Mn)-Al-C alloys, while other work observes only a metastable fcc phase in the same composition range. The metastable phases and/or microstructures in both nickel and iron aluminides are destroyed by annealing at temperatures above 750 K, with subsequent degradation of mechanical properties. Rapid solidification studies of several other intermetallic compounds are briefly noted.

Koch, C. C.↗
NASA NTRS1990

Chemical interactions in the aluminum-carbon and aluminum-silicon carbide systems

XPS was used to investigate the influence of O2 and H2O on the formation of aluminum carbide at Al-C and Al-SiC interfaces. It was determined that dosing the interfaces with H2O catalyzed the formation of aluminum carbide in both systems. This result is consistent with the oxidation model of carbide formation (developed to understand the kinetics of aluminum carbide formation at graphite-aluminum interfaces). These results imply that the formation of aluminum carbide in graphite- and SiC-reinforced metal-matrix composites, which severely degrades the composite mechanical properties by degrading the fiber and interface strength is catalyzed.

Maruyama, Benji↗
DOE OSTI2020

Materials Data on Al4C3 by Materials Project

Al4C3 is Aluminum carbonitride-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four equivalent C4- atoms to form a mixture of corner and edge-sharing AlC4 trigonal pyramids. There are three shorter (1.97 Å) and one longer (2.18 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of corner and edge-sharing AlC4 tetrahedra. There are one shorter (1.93 Å) and three longer (2.18 Å) Al–C bond lengths. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CAl6 octahedra, corners with six equivalent CAl5 trigonal bipyramids, and edges with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 63°. In the second C4- site, C4- is bonded to six equivalent Al3+ atoms to form CAl6 octahedra that share corners with six equivalent CAl5 trigonal bipyramids and edges with six equivalent CAl6 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al4C3 by Materials Project

Al4C3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a 5-coordinate geometry to five C4- atoms. There are a spread of Al–C bond distances ranging from 1.98–2.20 Å. In the second Al3+ site, Al3+ is bonded in a 4-coordinate geometry to four C4- atoms. There are a spread of Al–C bond distances ranging from 2.00–2.33 Å. In the third Al3+ site, Al3+ is bonded in a distorted see-saw-like geometry to four C4- atoms. There are a spread of Al–C bond distances ranging from 2.01–2.23 Å. In the fourth Al3+ site, Al3+ is bonded in a distorted trigonal non-coplanar geometry to three C4- atoms. There are one shorter (2.01 Å) and two longer (2.10 Å) Al–C bond lengths. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to five Al3+ atoms to form corner-sharing CAl5 trigonal bipyramids. In the second C4- site, C4- is bonded in a 6-coordinate geometry to five Al3+ and one C4- atom. The C–C bond length is 1.75 Å. In the third C4- site, C4- is bonded in a 7-coordinate geometry to six Al3+ and one C4- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al4C3 by Materials Project

Al4C3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a distorted square co-planar geometry to four C4- atoms. There are a spread of Al–C bond distances ranging from 2.11–2.41 Å. In the second Al3+ site, Al3+ is bonded in a 3-coordinate geometry to three C4- atoms. There are a spread of Al–C bond distances ranging from 2.04–2.21 Å. In the third Al3+ site, Al3+ is bonded in a distorted rectangular see-saw-like geometry to four C4- atoms. There are a spread of Al–C bond distances ranging from 2.10–2.41 Å. In the fourth Al3+ site, Al3+ is bonded in a water-like geometry to two C4- atoms. There are one shorter (2.03 Å) and one longer (2.08 Å) Al–C bond lengths. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to five Al3+ and one C4- atom to form distorted corner-sharing CAl5C octahedra. The corner-sharing octahedral tilt angles are 9°. The C–C bond length is 1.51 Å. In the second C4- site, C4- is bonded in a 6-coordinate geometry to five Al3+ and one C4- atom. The C–C bond length is 1.51 Å. In the third C4- site, C4- is bonded in a 5-coordinate geometry to three Al3+ and two C4- atoms.

36 MATERIALS SCIENCE↗