MoSi2 laminate processed by tape casting: Microstructure and mechanical propertiesʹ investigation

In this investigation multilayered MoSi2 was processed by tape casting, stacking of layers, debinding and pressureless sintering. The debinding treatment was optimized by means of thermogravimetric analysis and the effect of the sintering temperature on both microstructure and properties of the laminate was studied. The laminate microstructure was investigated and during sintering several phenomena were observed: reaction giving secondary phases (SiC and Mo4.8Si3C0.6), reduction of silica contaminating the starting powders by carbonaceous residue left after debinding, coalescence of porosity and grain growth. Flexural and tensile strength, modulus, hardness and KIc were measured. The material behaviour in oxidising environment was assessed up to 1600 °C. The composite laminate showed enhanced strength and stiffness over monolithic MoSi2. A toughening effect based on crack deviation was observed for MoSi2 laminate. The material displayed self-passivating behaviour at high temperature and only limited oxidation in the temperature range where usually MoSi2 suffers pesting.