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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on ScOF by Materials Project

ScOF is Baddeleyite-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sc3+ is bonded to four equivalent O2- and three equivalent F1- atoms to form a mixture of distorted corner and edge-sharing ScO4F3 pentagonal bipyramids. There are a spread of Sc–O bond distances ranging from 2.08–2.16 Å. There are a spread of Sc–F bond distances ranging from 2.15–2.30 Å. O2- is bonded to four equivalent Sc3+ atoms to form a mixture of distorted corner and edge-sharing OSc4 tetrahedra. F1- is bonded in a 3-coordinate geometry to three equivalent Sc3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScOF by Materials Project

ScOF is zeta iron carbide-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sc3+ is bonded to three equivalent O2- and three equivalent F1- atoms to form a mixture of distorted edge and corner-sharing ScO3F3 octahedra. The corner-sharing octahedra tilt angles range from 45–60°. There are a spread of Sc–O bond distances ranging from 1.98–2.04 Å. There are two shorter (2.19 Å) and one longer (2.33 Å) Sc–F bond lengths. O2- is bonded in a distorted trigonal planar geometry to three equivalent Sc3+ atoms. F1- is bonded in a distorted trigonal planar geometry to three equivalent Sc3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScOF by Materials Project

ScOF crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sc3+ is bonded in a body-centered cubic geometry to four equivalent O2- and four equivalent F1- atoms. All Sc–O bond lengths are 2.10 Å. All Sc–F bond lengths are 2.37 Å. O2- is bonded to four equivalent Sc3+ atoms to form distorted OSc4 tetrahedra that share corners with four equivalent OSc4 tetrahedra, corners with twelve equivalent FSc4 tetrahedra, edges with two equivalent FSc4 tetrahedra, and edges with four equivalent OSc4 tetrahedra. F1- is bonded to four equivalent Sc3+ atoms to form distorted FSc4 tetrahedra that share corners with four equivalent FSc4 tetrahedra, corners with twelve equivalent OSc4 tetrahedra, edges with two equivalent OSc4 tetrahedra, and edges with four equivalent FSc4 tetrahedra.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Topological reaction rate measurements related to scoffing

A ball-on-plate (both consisting of hardened M-50 steel) sliding elastohydrodynamic contact was run with trimethylolpropane triheptanoate (TMPTH) with and without tricresyl phosphate (TCP). The contact area of the plate was optically profiled with a phase-locked interference microscope (PLIM) both before and after exposure to alcoholic hydrochloric acid. As scuffing was approached, the profile within the contact region changed more rapidly after the acid treatment; after scuffing, it assumed a constant high value. A metallurgical phase found in the scuff mark was apparently responsible for the high reactivity. The microscopic profile changes (sensitivity, + or - 3 nm (+ or - A) in depth) involved primarily the small asperities (radius, 3 microns); the larger ones were unaffected. Soaking the steel in TCP smoothed the fine structure of the surface profile but increased its reactivity toward alcoholic hydrochloric acid before sliding was started. Thus it would appear that PLIM examination could be used for screening potentially scuff-resistant materials.

Lauer, J. L.↗