First-principles study of the interfacial adhesion between SiO2 and MoSi2

D. E. Jiang and Emily A. Carter
Phys. Rev. B 72, 165410 – Published 10 October 2005

Abstract

Upon oxidation, a silica scale forms on MoSi2, a potential high-temperature coating material for metals. This silica scale protects MoSi2 against high-temperature corrosive gases or liquids. We use periodic density functional theory to examine the interface between SiO2 and MoSi2. The interfacial bonding is localized, as evidenced by an adhesion energy that changes only slightly with the thickness of the SiO2 layer. Moreover, the adhesion energy displays a relatively large (0.40Jm2) variation with the relative lateral position of the SiO2 and MoSi2 lattices due to changes in SiO bonding across the interface. The most stable interfacial structure yields an ideal work of adhesion of 5.75Jm2 within the local density approximation (5.02Jm2 within the generalized-gradient approximation) to electron exchange and correlation, indicating extremely strong adhesion. Local densities of states and electron density difference plots demonstrate that the interfacial SiO bonds are covalent in character. MoO interactions are not found in the SiO2MoSi2 interface investigated here. Our work predicts that the SiO2 scale strongly adheres to MoSi2, and further supports the potential of MoSi2 as a high-temperature structural material and coating.

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  • Received 17 May 2005

DOI:https://doi.org/10.1103/PhysRevB.72.165410

©2005 American Physical Society

Authors & Affiliations

D. E. Jiang1 and Emily A. Carter2

  • 1Department of Chemistry and Biochemistry, Box 951569, University of California, Los Angeles, California 90095-1569, USA
  • 2Department of Mechanical and Aerospace Engineering and Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey 08544-5263, USA

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Vol. 72, Iss. 16 — 15 October 2005

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