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ACS Appl Mater Interfaces. 2018 Jun 13;10(23):19712-19720. doi: 10.1021/acsami.8b04497. Epub 2018 May 29.

High-Temperature Corrosion Behavior of SiBCN Fibers for Aerospace Applications.

Author information

1
Science and Technology on Advanced Ceramic Fibers and Composites Laboratory , National University of Defense Technology , Changsha 410073 , PR China.

Abstract

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 °C 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-N 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 α-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-C, and Si-N units reacting with oxygen diffusing inward, which protects h-BN grains formed by networks of B-N 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.

KEYWORDS:

SiBCN fiber; aerospace applications; combustion; corrosion; mechanism; oxidation resistivity

PMID:
29767945
DOI:
10.1021/acsami.8b04497

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