Young's Modulus of Silicon Nitride Hot Pressed with Cearia Additions

Possible relationships between Young's modulus at room temperature of (1-20) wt% CeO2-fluxed HPSN and some microstructural features such as amount of the intergra­nular phase, porosity, a/? ratio and crystallographic texture have been investigated. The dependence of Young's modulus on amount of integranular phase expressed in terms of the Cohen-lshai model resulted in the relation: E= 98.0 [1 + V N l (1.45- V N1/3)] GN/ m2. A quadratic rela­ tionship, E = 290.0 (1-AP + BP2), proved the most adequate to account for the effect of porosity on Young's modulus over the 0-36% porosity range. a/? ratio and texture did not seem to have an appreciable effect.