It is known that $Si_3N_4$ bonded SiC has almost all the valuable properties needed for the high temperature material and thus has very wide range of applicability.
Si powder and two different sized (70μ and 250μ respectively) SiC powder were used as the raw materials. Specimens were prepared by heating the green compact made of the raw materials in the nitrogen atmosphere. PVA (Polyvinyl Alcohol) was used as the temporay organic binder. The bonding of SiC particles is brought about with the formation of RBSN (Reation Bonded Silicon Nitride).
The influences of the variation of the relative amounts of the raw materials, the amount of the organic binder, and the compacting pressure on the density and the bend strength of the specimens were investigated.
It was shown that the calculation of the amount of the nitridation of Si is somewhat complicated matter since some portion of the organic binder reacts with the Si during the firing process.
Fixing the Si amount to weight percents, the distributions of the size of the SiC particles that gives the maximum density and the maximum strength was gained through experiments. It was observed that the two distributions were not equal to each other.
As the amount of Si increased, the reaction amount of Si with nitrogen and the strength increased.
It was observed that high compacting pressure gives both high density and high strength.
The fracture mode was intergranular for the most part and the transgranular fracture was scarcely observed.
