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At least 1,279 records · Page 71
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on C by Materials Project

C crystallizes in the orthorhombic Immm space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. there are nine inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to three C atoms. There are a spread of C–C bond distances ranging from 1.39–1.47 Å. In the second C site, C is bonded to four C atoms to form edge-sharing CC4 tetrahedra. There is two shorter (1.52 Å) and two longer (1.60 Å) C–C bond length. In the third C site, C is bonded in a trigonal planar geometry to three C atoms. There are a spread of C–C bond distances ranging from 1.40–1.45 Å. In the fourth C site, C is bonded in a trigonal planar geometry to three C atoms. There is one shorter (1.39 Å) and one longer (1.53 Å) C–C bond length. In the fifth C site, C is bonded in a trigonal planar geometry to three C atoms. Both C–C bond lengths are 1.44 Å. In the sixth C site, C is bonded in a trigonal planar geometry to three C atoms. The C–C bond length is 1.48 Å. In the seventh C site, C is bonded in a trigonal planar geometry to three C atoms. The C–C bond length is 1.39 Å. In the eighth C site, C is bonded in a trigonal planar geometry to three C atoms. In the ninth C site, C is bonded to four C atoms to form edge-sharing CC4 tetrahedra. There is one shorter (1.61 Å) and one longer (1.62 Å) C–C bond length.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Materials Data on C by Materials Project

C is Copper structured and crystallizes in the cubic Pa-3 space group. The structure is zero-dimensional and consists of four fullerene molecules. there are ten inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to three C atoms. There is one shorter (1.40 Å) and two longer (1.45 Å) C–C bond length. In the second C site, C is bonded in a trigonal planar geometry to three C atoms. There is one shorter (1.40 Å) and two longer (1.45 Å) C–C bond length. In the third C site, C is bonded in a trigonal planar geometry to three C atoms. There is one shorter (1.40 Å) and one longer (1.46 Å) C–C bond length. In the fourth C site, C is bonded in a trigonal planar geometry to three C atoms. There is one shorter (1.40 Å) and two longer (1.45 Å) C–C bond length. In the fifth C site, C is bonded in a trigonal planar geometry to three C atoms. Both C–C bond lengths are 1.45 Å. In the sixth C site, C is bonded in a trigonal planar geometry to three C atoms. There is one shorter (1.40 Å) and one longer (1.45 Å) C–C bond length. In the seventh C site, C is bonded in a trigonal planar geometry to three C atoms. In the eighth C site, C is bonded in a trigonal planar geometry to three C atoms. In the ninth C site, C is bonded in a trigonal planar geometry to three C atoms. In the tenth C site, C is bonded in a trigonal planar geometry to three C atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Materials Data on C by Materials Project

C crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four C clusters. there are seven inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to three C atoms. There are a spread of C–C bond distances ranging from 1.37–1.54 Å. In the second C site, C is bonded in a bent 120 degrees geometry to two C atoms. There is one shorter (1.29 Å) and one longer (1.39 Å) C–C bond length. In the third C site, C is bonded in a bent 120 degrees geometry to two C atoms. The C–C bond length is 1.29 Å. In the fourth C site, C is bonded in a trigonal planar geometry to three C atoms. The C–C bond length is 1.40 Å. In the fifth C site, C is bonded in a bent 120 degrees geometry to two C atoms. The C–C bond length is 1.31 Å. In the sixth C site, C is bonded in a bent 120 degrees geometry to two equivalent C atoms. In the seventh C site, C is bonded in a bent 120 degrees geometry to two C atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Effects of Mo on microstructure of as-cast 28 wt.% Cr–2.6 wt.% C–(0–10) wt.% Mo irons

Microstructures of as-cast 28 wt.% Cr–2.6 wt.% C irons containing (0–10) wt.% Mo with the Cr/C ratio of about 10 were studied and related to hardness. The experimental irons were cast into dry sand molds. Microstructural investigation was performed by light microscopy, X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectrometry. It was found that the iron with about 10 wt.% Mo was eutectic/peritectic, whereas the others with less Mo content were hypoeutectic. The matrix in all irons was austenite, partly transformed to martensite during cooling. Mo addition promoted the formation of M{sub 23}C{sub 6} and M{sub 6}C. At 1 wt.% Mo, multiple eutectic carbides including M{sub 7}C{sub 3}, M{sub 23}C{sub 6} and M{sub 6}C were observed. M{sub 23}C{sub 6} existed as a transition zone between eutectic M{sub 7}C{sub 3} and M{sub 6}C, indicating a carbide transition as M{sub 7}C{sub 3}(M{sub 2.3}C) → M{sub 23}C{sub 6}(M{sub 3.8}C) → M{sub 6}C. At 6 wt.% Mo, multiple eutectic carbides including M{sub 7}C{sub 3} and M{sub 23}C{sub 6} were observed together with fine cellular/lamellar M{sub 6}C aggregates. In the iron with 10 wt.% Mo, only eutectic/peritectic M{sub 23}C{sub 6} and M{sub 6}C were found without M{sub 7}C{sub 3}. Mo distribution to all carbides has been determined to be increased from ca. 0.4 to 0.7 in mass fraction as the Mo content in the irons was increased. On the other hand, Cr distribution to all carbides is quite constant as ca. 0.6 in mass fraction. Mo addition increased Vickers macro-hardness of the irons from 495 up to 674 HV{sub 30}. High Mo content as solid-solution in the matrix and the formation of M{sub 6}C or M{sub 23}C{sub 6} aggregates were the main reasons for hardness increase, indicating potentially improved wear performance of the irons with Mo addition. - Highlights: • Mo promoted the formation of M{sub 23}C{sub 6} and M{sub 6}C in the irons with Cr/C ratio of about 10. • M{sub 23}C{sub 6} has higher Fe/Cr and Mo/Cr atm% ratios than M{sub 7}C{sub 3}. • Si content and high Mo content over about 9 atm% are characteristics of M{sub 6}C. • No M{sub 7}C{sub 3} was found at 10 wt.% Mo addition, only M{sub 23}C{sub 6} and M{sub 6}C presented. • High Mo matrices and M{sub 23}C{sub 6}/M{sub 6}C aggregates increased iron macro-hardness.

36 MATERIALS SCIENCE↗