Effect Porosity on Strength of Porous Alumina

Porous alumina ceramics were obtained by preparing the specimens with various amounts of carbon powder used as pore-forming material. Samples of from 20% to 55% porosity were sintered. Effect of porosity and degree of specimen sintered on strength were investigated. It is show that the strength (σ) of specimens with changing porosity (ρ) can be represented by the empirical equation σ=σ₀(1-ρ)^m at low degree of specimens sintered or σ=σ₀exp(-bρ)at high degree of specimens sintered. The empirical constants m,σ₀ and b is dependent on the degree of specimens sintered. With increasing of the degree of specimens sintered, the value of m, σ₀ and b decrease. The only method to obtain the specimens with high porosity and strength was by addition of pore-forming material not by decreasing degree of specimens sintered.