Microstructure And Mechanical Behavior Of Tio2-Mno-Doped Alumina/Alumina Laminates

Tapes of TiO2-MnO-doped alumina (d-Al2O3) and pure alumina (Al2O3) were shaped via tape casting. Laminates with three different layer numbers and respective thicknesses were produced and sintered at 1200 degrees C. The microstructure and mechanical behavior of laminates were investigated and compared to the respective monolithic references (d-Al2O3 and Al2O3). The use of dopants in alumina decreased the initial sintering temperature, leading to higher densification at 1200 degrees C (similar to 98% theoretical density (TD)) when compared to Al2O3(similar to 73% TD). The higher density was reflected in a higher Young's modulus and hardness for doped alumina. A region of diffusion of dopants in pure alumina layers was observed along the interface with doped layers. The mechanical strength of d-Al2O3 samples sintered at 1200 degrees C was not statistically different from Al2O3 samples sintered at 1350 degrees C. The strength of laminates composed of doped layers with undoped, porous interlayers did not change. Nevertheless, as the thickness of these porous interlayers increases, a loss of strength was observed. Monolithic references showed constant values of fracture toughness (K-IC), similar to 2 MPa.m(1/2), and linear crack path. On the other hand, K-IC of laminates increases when the crack propagates from weak Al(2)O(3)layers to dense d-Al2O3 layers.