Temperature-dependent water corrosion mechanism of silicon carbide: Atomic insights from reactive molecular dynamics simulation

Silicon carbide (SiC) is an ideal material for both aeronautics and space industries, but SiC is highly susceptible to water corrosion at high temperature. A clear understanding of water corrosion mechanisms of SiC is still lacking because the complex interaction dynamics are extremely difficult to be investigated experimentally. In this study, the temperature-dependent of water corrosion mechanism of SiC was investigated by reactive molecular dynamics simulation, and three different corrosion regimes were observed with the increase of the ambient temperature. In regime I (below 1000 K), only Si-H and Si-OH terminations were formed on SiC surface and almost no corrosion occurred; in regime II (1000 - 1500 K), the same number of carbon and silicon atoms were corroded in the form of gaseous molecules, and the relation between the number of atoms lost and temperature was in good agreement with the Arrhenius expectation; lastly, in regime III (above 1500 K), the number of Si-O-Si groups formed exceeded the volatilized number, leading to the obvious retention of the Si-O-Si network structures. These results can guide the design and preparation of SiC materials for aerospace applications by providing an atomic insight into the mechanisms of water corrosion on SiC.