Characterization of Mo-SiO sub 2 functionally graded materials

Mo/SiO sub 2 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 approx20-25 vol.% 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 SiO sub 2 . 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 (approx2 wt.%) 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.