Biaxial strength, fracture toughness and subcritical crack growth are reported for coarse grained porous alumina ceramics. The materials were prepared with a varying amount of a silica sintering aid, which resulted in the formation of a glassy secondary phase at the grain boundaries. Crystalline mullite was additionally found in the material with the highest silica content. The biaxial strength, measured by Ball-on-Ring and Ball-on-3-Balls, was highest for the material without mullite at the grain boundaries, and the biaxial strength decreased with increasing porosity. The fracture toughness of the materials was in the range of 1.7–1.9 MPa m^0.5. Measurements of subcritical crack growth by a modified lifetime method in air and aqueous environments demonstrated a higher crack growth rate in water and acid relative to in air. The effect of porosity and grain boundary phase were discussed in relation to subcritical crack growth and fracture mode in the coarse grained alumina ceramics.

据报道，粗粒多孔氧化铝陶瓷具有双轴强度，断裂韧性和亚临界裂纹扩展。用不同量的二氧化硅烧结助剂制备材料，这导致在晶界处形成玻璃状第二相。另外在材料中发现了具有最高二氧化硅含量的结晶莫来石。对于在晶界处没有莫来石的材料，通过环上球和3球上球测得的双轴强度最高，并且双轴强度随着孔隙率的增加而降低。材料的断裂韧性在1.7–1.9 MPa m ^0.5的范围内。通过改良寿命方法在空气和水环境中对亚临界裂纹扩展的测量表明，相对于空气，水和酸中的裂纹扩展率更高。讨论了孔隙度和晶界相与粗晶粒氧化铝陶瓷中亚临界裂纹扩展和断裂方式的关系。