%0 Journal Article
%T High-Temperature Corrosion Behavior of SiBCN Fibers for Aerospace Applications
%J -
%D 2018
%R https://doi.org/10.1021/acsami.8b04497
%X Amorphous SiBCN fibers possessing superior stability against oxidation have become a desirable candidate for high-temperature aerospace applications. Currently, investigations on the high-temperature corrosion behavior of these fibers for the application in high-heat engines are insufficient. Here, our polymer-derived SiBCN fibers were corroded at 1400 ¡ãC in air and simulated combustion environments. The fibers¡¯ structural evolution after corrosion in two different conditions and the potential mechanisms are investigated. It shows that the as-prepared SiBCN fibers mainly consist of amorphous networks of SiN3C, SiN4, B¨CN hexatomic rings, free carbon clusters, and BN2C units. High-resolution transmission electron microscopy cross-section observations combined with energy-dispersive spectrometry/electron energy-loss spectroscopy analysis exhibit a trilayer structure with no detectable cracks for fibers after corrosion, including the outermost SiO2 layer, the h-BN grain-contained interlayer, and the uncorroded fiber core. A high percentage of water vapor contained in the simulated combustion environment triggers the formation of abundant ¦Á-cristobalite nanoparticles dispersing in the amorphous SiO2 phase, which are absent in fibers corroded in air. The formation of h-BN grains in the interlayer could be ascribed to the sacrificial effects of free carbon clusters, Si¨CC, and Si¨CN units reacting with oxygen diffusing inward, which protects h-BN grains formed by networks of B¨CN hexatomic rings in original SiBCN fibers. These results improve our understanding of the corrosion process of SiBCN fibers in a high-temperature oxygen- and water-rich atmosphere
%U https://pubs.acs.org/doi/10.1021/acsami.8b04497