Characterization of Mo-SiO2 functionally graded materials

Mo/SiO2 functionally graded materials (FGMs) have been prepared by combined slip casting and sedimentation techniques. The final, sintered samples have a gradient in molybdenum content, with a maximum value of similar to 20 to 25 vol pet Mo. At one:edge, the FGM is a good electrical conductor (for approximately one-third of the total length), while the opposite end is composed mainly of fused SiO2. The variation of electrical resistivity, hardness, toughness, and thermal expansion along the gradient has been analyzed. The FGMs sintered In vacuum contained a small amount of Mo oxide (similar to 2 wt pct) as a third phase. The oxide originated from the starting Mo powders and oxidation during presintering. The oxide was in the form of discrete particles and did not appreciably affect the measured properties. The Mo content had the expected effect on the FGM properties; an increase in Mo increases resistivity, thermal expansion, and toughness.