Compressive creep behavior of hot-pressed Si3N4 ceramics using alumina and a rare earth solid solution as additives

The compressive creep behavior of the materials depends on the composition and amount of the intergranular phase. While higher amounts of additives resulted in higher creep rates, ε˙, and higher stress exponents, the activation energy Qss, has been inferior for samples with lower additive contents, n. This observation is attributed to the higher SiO2 content due to the higher amount of Si3N4 in the starting powders, resulting in liquid phase formation at lower temperatures. Grain sliding has been identified to be the predominant mechanism responsible for creep deformation of these ceramics.