Kamacite sulfurization in the solar nebula

摘要: The kinetics and mechanisms of kamacite sulfurization were studied experimentally at tempera- tures H2S/H2 ratios relevant to the solar nebula. Pieces Canyon Diablo meteorite heated 558 K, 613 643 K in 50 parts per million by volume (ppmv) H2S-H2 gas mixtures for up one month. Optical microscopy x-ray diffraction analyses show that morphology crystal orientation resulting sulfide layers vary with both time temperature. Electron microprobe reveal three distinct phases reaction products: monosulfide solid solution (mss), (Fe,Ni,Co)l,S, pentlandite (Fe,Ni,Co)g,Ss, a P-rich phase. bulk composition remnant metal was not significantly changed sulfurization. Kamacite followed parabolic entire duration experiments. Sulfide formed grew linearly time, while those initially then switched upon reaching critical thickness. experimental results suggest variety thermodynamic, kinetic, physical processes control final layers. We combine morphological, diffraction, elec- tron microprobe, kinetic data produce comprehensive model formation Then, we present set criteria assist identification nebula condensate sulfides primitive meteorites.