Mechanical behaviors of alumina ceramics doped with rare-earth oxides

The effects of three types of additives Y₂O₃, La ₂O₃, and Sm₂O₃ on the sintering and mechanical behaviors of alumina ceramics were investigated. The bending strengths of alumina ceramics with Sm₂O₃ and Y ₂O₃ additions were 455 and 439 MPa, respectively, higher than that with La₂O₃ addition. The fracture toughness of the ceramics with Sm₂O₃ and Y₂O₃ were also higher than that with La₂O₃ addition. The fracture mode of rare earth oxides doped alumina ceramics exhibited obvious transgranular fractures as well as intergranular fracture. The results of research show that the improvement of bending strength and fracture toughness of alumina ceramics with rare earth oxides was achieved by refining the grain size and strengthening the grain boundary.