PROCESSING AND MECHANICAL-PROPERTIES OF SI3N4-SIC WHISKER-TIN SYSTEM COMPOSITE-MATERIALS

In a whisker containing slurry, the correlation between pH and the viscosity of the slurry was effectively utilized to achieve a homogeneous distribution of whiskers in a matrix. The process consists of two-step adjustment of the slurry pH. The application of the process to the Si3N4-SiC Whisker-TiN particulate ternary system achieved the room temperature strength higher than 900 MPa. The strength degradation due to incorporation of whisker was minimized by this process. The high temperature flexural strength for the Si3N4-SiC whisker-TiN ternary system composite was as high as 600 MPa at 1400-degrees-C, which was higher than that Of Si3N4-TiN composites. The fracture toughness was also improved by the ternary system composite comparing to the matrix Si3N4.