Effect of Nb–Al–SiC elements combined with pre-oxidation treatment on the pesting resistance of MoSi2

Abstract

Abstract Nb, Al, SiC elements were introduced into the matrix to improve the pest phenomenon of the MoSi2 composites. The results showed that although the oxidation rate of the composite decreased, the pest phenomena eventually occurred at the oxidation temperature of 500 °C and 750 °C. And after 120 h of oxidation, the bending strength of the composite decreased dramatically from 472 MPa to 258 MPa (500 °C) and 225 MPa (750 °C). In order to solve this problem, pre-oxidation has been adopted. During pre-oxidation at 1200 °C via exposure to air, a dense fibrous layer was in-situ formed, which had excellent adhesion to the matrix. The substrate which adjoins the interface of the oxide layer and matrix was oxidized into nano-sized grains. This layer and the nano-sized substrate played important roles in eliminating the pest phenomenon of the MoSi2 composite.