Fabrication of Functionally Graded MoSi₂/ZrO₂ (2 mol% Y₂O₃) Materials by Wet-Molding Process

Abstract

Functionally graded MoSi₂/ZrO₂(2Y) materials with high density (97.5% of theoretical) have been fabricated by uniaxial wet-molding, followed by hot pressing (1000°C/1h/30MPa) and hot isostatic pressing (1400°C/2h/196MPa). Their composition profiles are much influenced by the viscosity of the mixed solutions of glycerin and ethanol used as dispersion media; a linear compositional gradient from MoSi₂/ZrO₂(2Y)≈70/30 to≈20/80 mol% is obtained from the solution (50/50 vol%) with the viscosity of 20 mPa⋅s. Vickers hardness Hv and fracture toughness K_Ic increase from 9.7 to 12.4 GPa and 5.1 to 12.5 MPa⋅m^1/2, respectively, with increasing ZrO₂(2Y) composition.