Development of new waterproof thin-layers for the magnetic alloy core and structural study by neutron reflectometry

The mechanism of the waterproof property of perhydropolysilazane (PHPS) and CH₃ group modified PHPS derived silica (PDS or Me-PDS) thin layers synthesized on substrates was revealed by FT-IR and neutron reflectivity (NR) analysis. FT-IR results revealed that the Me-PDS thin layer undergoes considerable C-H bond absorption. This result suggests that the synthesized thin Me-PDS layer contains large amount of methyl group The general SiO₂ network structure would be presented in the PDS and Me-PDS thin layers because both thin layers have clear Si-O absorption peaks. NR analysis revealed that the thickness of the PDS and Me-PDS thin layers was 21 nm and 22 nm, respectively. In addition, the penetration depth of water into the PDS and Me-PDS thin layers were analysed and these results suggest that the Me-PDS thin layer is more hydrophobic than the PDS thin layer, a consequence of the modification of the PDS thin layer by introduction of the hydrophobic CH₃ group. (author)