Preparation of Translucent Ceramic from Al2O3 nanopowder by pressureless sintering method

In this article، the effect of type and content additive on sintering behavior and properties of translucent alumina ceramics were investigated. α-Al2O3 nanopowder with various content of additives (MgO، La2O3)، was compacted under a pressure of 300MPa and was sintered at temperatures of 1700 and 1875 ºC. The microstructure of sintered samples were studied by scanning electron microscope (SEM) and Optical microscope. The results indicate that with increasing content of MgO increase formation of Spinel secondary phase within grains that these flaws act as points of scattering and reduce the transparency of the sample. With increase La2O3 alumina grains with almost no pores trapped in، become fine and compact. Alumina codoped with 0. 12%wt MgO and 0. 2%wt La2O3 sintered at 1750 °C for 1 h show maximum transmittance 60%، hardness 1840 VHN and relative density 99. 95%.