Fabrication of dense silicon carbide through aqueous slurries containing well-dispersed carbon as a sintering aid

Abstract

Tetramethyl ammonium hydroxide (TMAOH) has no fluidizing effect on carbon particles, because of their hydrophobic surface properties. On the other hand, styrene/maleic copolymer (SM) enhanced the fluidity of two kinds of carbon slurries in the basic pH range, where the particle diameters of carbon {#}2650 and MA100 were 13 and 22 nm, respectively. High-density sintered bodies of silicon carbide containing carbon and boron carbide as sintering aids were obtained by controlling the pH of ∼ 10–11 with TMAOH and by addition of SM: i.e., 9.5 and 5.5 wt% of SM were added to #2650 and MA100, respectively, in the dry weight base of the carbon. The highest sintered density product with more than 98% was obtained by intimate dispersion of the finer carbon particles in the silicon carbide slurries.