Effect of MoSi2 content on dielectric and mechanical properties of
MoSi2/Al2O3 composite coatings
MoSi2/Al2O3 composite coatings
(State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
Abstract: Molybdenum disilicide (MoSi2) sheath and aluminum oxide (Al2O3) core blended powders were fabricated by spray drying. A derived coating material was produced for the application as microwave absorbers using the as prepared powders by atmospheric plasma spray (APS) technology. The effects of MoSi2/Al2O3 mass ratio on the dielectric and physical mechanical properties of the composite coatings were investigated. When the MoSi2 content of the composites increases from 0 to 45%, the flexure strength and fracture toughness improve from 198 to 324 MPa and 3.05 to 4.82 MPa∙m1/2 then decline to 310 MPa and 4.67 MPa∙m1/2, respectively. The dielectric loss tangent increases with increasing MoSi2 content, and the real part of permittivity decreases conversely over the frequency range of 8.2−12.4 GHz. These effects are due to the agglomeration of early molten MoSi2 particles and the increase of the electrical conductivity with increasing MoSi2 content.
Key words: MoSi2/Al2O3 composite coating; atmospheric plasma spraying; mechanical properties; dielectric properties