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DOE OSTI2020

Materials Data on K2SiO3 by Materials Project

K2SiO3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of K–O bond distances ranging from 2.74–3.24 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.72–3.30 Å. In the third K1+ site, K1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of K–O bond distances ranging from 2.62–2.89 Å. In the fourth K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.64–3.08 Å. In the fifth K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.60–2.87 Å. In the sixth K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.79–3.26 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.70 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.70 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is two shorter (1.62 Å) and two longer (1.70 Å) Si–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to four K1+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to five K1+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Si4+ atoms.

36 MATERIALS SCIENCE↗

NASA NTRS1992

Four space application material coatings on the long-duration exposure flight (LDEF)

Four material coatings of different thickness were flown on the LDEF to determine their ability to perform in the harsh space environment. The coatings, located in the ram direction of the spacecraft, were exposed for 10 months to the low-Earth orbit (LEO) environment experienced by the LDEF at an orbit of 260 nautical miles. They consisted of indium oxide (In2O3), silicon oxide (SiO(x)), clear RTV silicone, and silicone with silicate-treated zinc oxide (ZnO). These coatings were flown to assess their behavior when exposed to atomic oxygen and to confirm their good radiative properties, stability, electrical conductivity, and resistance to UV exposure. The flown samples were checked and compared with the reference unflown samples using high-magnification optical inspection, ESCA analysis, weight changes and dimensional changes. These comparisons indicated the following: The 1000 A SiO(x) coating eroded uniformly, with minor changes in its radiative properties. The 100 A of In2O3 coating eroded completely down to the Kapton backing, with resultant losses of reflectance. The RTV-615 showed erosion, with carbon (C) content losses, while the Si remained constant, with a doubling of the oxygen (O) concentration. The RTV-615 silicone with K2SiO3-treated ZnO changed from flat to glossy white in appearance. It lost C, was etched, and increased its O content. The upper layers showed no remaining Zn or K. Losses of reflectance occurred within certain wavelength bands. It was not possible to evaluate the experimental oxygen reaction rate using the calculated atomic oxygen fluence of 2.6 x 10(exp 20) atoms/cm(exp 2) for the exposure of these coatings during the flight. The bakeout of the coatings was not carried out prior to the flight. Hence, the coating weight and dimensional losses included losses by outgassing products.

Scialdone, John J.↗

NASA NTRS1995

Four space application material coatings on the Long-Duration Exposure Facility (LDEF)

Four material coatings of different thicknesses were flown on the LDEF to determine their ability to perform in the harsh space environment. The coatings, located in the ram direction of the spacecraft, were exposed for 10 months to the low-Earth orbit (LEO) environments experienced by the LDEF at an orbit of 260 nautical miles. They consisted of indium oxide (In2O3), silicon oxide (SiO(x)), clear RTV silicone, and silicone with silicate-treated zinc oxide (ZnO). These coatings were flown to assess their behavior when exposed to atomic oxygen and to confirm their good radiative properties, stability, electrical conductivity, and resistance to UV exposure. The flown samples were checked and compared with the reference unflown samples using high-magnification optical inspection, ESCA analysis, weight changes, and dimensional changes. These comparisons indicated the following. The 1000 A SiO(x) coating eroded uniformly, with minor changes in its radiative properties. The 100 A In2O3 coating eroded completely down to the Kapton backing, with resultant losses of reflectance. The RTV-615 showed erosion, with carbon (C) content losses, while the Si remained constant, with a doubling of the oxygen (O) concentration. The RTV-615 silicone with K2SiO3-treated ZnO changed from flat to glossy white in appearance. It lost C, was etched, and increased its O content. The upper layers showed no remaining Zn or K. Losses of reflectance occurred within certain wavelength bands. It was not possible to evaluate the experimental oxygen reaction rate using the calculated atomic oxygen fluence of 2.6 x 10(exp 20) atoms/cm(exp 2) for the exposure of these coatings during the flight. The bakeout of the coatings was not carried out prior to the flight. Hence, the coating weight and dimensional losses included losses by outgassing products.

Scialdone, John J.↗